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Chemical Reaction in Solution: Definition, Types, and...
Continue ReadingWhat is Chemical Reaction?
o Chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products.
Type of Chemical Reactions
There are three types of reaction that occurs in solution;
I. Precipitation reaction
II. Acid-base reaction
III. Oxidation-reduction reaction
I. Precipitation Reaction
o This reaction takes place when two aqueous reactants, one solid and one liquid, react to form an insoluble product. This insoluble substance is termed as a precipitate.
o For instance; lead nitrate is mixed with potassium to produce the following compounds as shown in the following chemical reaction:
Pb (NO3)2 + 2KI → PbI2 (ppt) + 2KNO3
o Lead iodide formed here is an insoluble product and hence is titled as a precipitate. Another example for the same include;
AgNO3(aq) + K2Cr2O7(aq) → Ag2Cr2O7(ppt) + KNO3(aq)
o A reddish precipitate of silver dichromate is formed in the above reaction. These reactions shown above are also termed as Double-displacement reactions.
II. Acid-Base reaction
o Arrhenius stated that an acid is defined as a substance that dissolves in water to produce H+ ions, for instance, HCl whereas a base is a substance that dissolves in water to produce hydroxide (OH−) ions.
o When an acid reacts with base in their solution form, they produce salt and water.
o These reactions are also named as Neutralization reactions.
The chemical reaction below shows some of the examples of acid-base reactions;
H2SO4 + Ca(OH)2 → CaSO4 + H2O
H2SO4 + CaO → CaSO4 + H2O
HF + H2O → F– + H3O+
HBr + NH3 → Br– + NH4+
III. Oxidation Reduction Reaction
o Oxidation is defined as a process in which a chemical substance loses electrons during a reaction whereas Reduction is the totally opposite process in which a substance gains electrons or gain hydrogen during a reaction.
o If in a reaction the total number of electrons lost is equal to the total number of electrons gained then these types of reactions are known as Redox reactions.
o The figure given below describes the redox reaction with an example;
Reduction: Removal of Oxygen from CuO
Oxidation: Addition of Oxygen in H2
CuO + H2 → Cu + H2O
Reduction: Removal of Oxygen from Fe3O4
Oxidation: Addition of Oxygen in H2
Fe3O4 + 4H2 → 3Fe + 4H2O
Types of Redox Reactions
o There are a few important types of redox reactions that are mentioned below;
o Synthesis Reactions: The formation of any compound straight from the elements in a redox reaction is known as synthesis reaction, for instance, the formation of water from hydrogen and oxygen as given below:
2H2(g)+O2(g) → 2H2O(g)
o Decomposition Reactions: The decomposition of a compound into its elements is also defined as a type of as redox reaction for instance; the electrolysis of water:
2H2O(l) → 2H2(g)+O2(g)
o Combustion Reactions: It is a kind of redox reaction which occurs between molecular oxygen and compound (reactants) to produce oxygen-containing products. For example;
CH4(g)+2O2(g) → CO2(g)+2H2O
Solution
o A solution is a type of homogeneous mixture in which substances that are present in lesser amounts are called solutes dispersed uniformly throughout the substance present in the greater amount, the solvent.
Types of Solution
o The solution can be of two types as mentioned below;
o Aqueous Solution
o A Non-aqueous Solution
o An aqueous solution is commonly defined as a solution in which the solvent is water, whereas, in a non-aqueous solution, the solvent is not water.
Examples of non-aqueous solvents include ethyl acetate, turpentine, etc.
Why Most Reaction Occur in Aqueous Solution
o For a chemical reaction to occur, individual atoms, molecules, or ions must collide thus, collisions between solids, do not occur at a visible rate.
o It is easy to control the amount of heat used or produced in a reaction when it occurs in an aqueous solution.
o The nature of the reaction can also be controlled when the proper solvent is chosen.
o All the chemical reaction that occurs in our body are possible only in aqueous solution.
o For instance; reaction involved in the digestion of food.
o When an element dissolves in water, it is represented by writing (aq) after its chemical name.
o Hydrophilic or Water-loving substances dissolve in water.
o For instance, when sodium chloride dissolves in water, dissociates into Na+(aq) and Cl– (aq).
o Hydrophobic or water-fearing substances normally do not dissolve in water or form aqueous solutions.
o Example for the same include mixing oil and water which will not result in any dissociation.
Solubility in Water
o Water has some unique properties and is available on Earth in a huge amount.
o Water is also called as a Universal solvent.
o The water molecule comprises of two hydrogen atoms bonded covalently to an oxygen atom in a V-shaped structure.
o The oxygen atom attracts electrons more strongly as compared to the hydrogen atom. It means that the oxygen and hydrogen nuclei do not share equal electrons.
o Hydrogen atoms are generally electron-poor and attain a partial positive charge, which is shown by δ+ whereas the oxygen atom, is more electron-rich, so it attains a partial negative charge.
o This above-mentioned charge is twice as large as the partial positive charge on each hydrogen as the molecule of water has a net zero charge. So, its charge is indicated by 2δ−.
o This unequal distribution of charge forms a polarity in the individual water molecules. Because of this arrangement of a water molecule, it is termed as a polar substance.
o The unequal distribution of charge in polar liquids such as water makes them good solvents for different ionic compounds.
o When ionic solid dissolves in water, the ions present dissociates into cation and anion. The partially negatively charged oxygen atoms of the H2O molecules surround the cations and the partially positively charged hydrogen atoms in H2O surround the anions.
o The arrangement in which cations and anions are surrounded by polar water molecules is termed as hydrated ions.
o Example for the same include; common salt in water.
Chemical Reaction Citations
- Understanding chemical reaction mechanisms in ionic liquids: successes and challenges. Chem Soc Rev . 2011 Jan;40(1):272-90.
- Chemical reactions which affect the biological activity of human gonadotrophins. Biochem J. 1961 Apr; 79(1): 64–70.
- Seeding chemical reactions by focusing. J Chem Phys . 2013 Apr 14;138(14):144502.
- Application of chemical reaction engineering principles to ‘body-on-a-chip’ systems. AIChE J . 2018 Dec;64(12):4351-4360.
- Chemical reactions. Am J Med Technol . 1948 May;14(3):142-6.
- Classification of chemical reactions and chemoinformatic processing of enzymatic transformations. Methods Mol Biol . 2011;672:325-40.
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Plant Cell vs Animal Cell: Definition and...
Continue ReadingPlant Cell vs Animal Cell
As animal cells are flexible, they don’t have cell wall, whereas plants have primary and secondary cell wall. Instead, plasma membrane is present in animal cells.
Plasmodesmata is not seen in animal cells which is seen in plant cell.
In plants during cell division, in the telophase a cell plate is seen, which is absent in animal cell and that process takes place when cell squeezes to form two cells.
Animals do contain centriole which is absent in plant cell. vacuoles are present in both but the size differs.
Animals have a very small vacuole whereas plants have a huge vacuole.
In animal cells, centrioles are present and in plant they are absent.
Plant Cell
Cell is the fundamental unit of life, which cannot be seen without the microscope. The shape of older cell is somewhat box or cuboidal consisting of 14 faces, whereas young cells are circular in shape. Plant can be categorized into two parts; one with the nucleus and everything except the nucleus is the cytoplasm.
Cell wall is found in plant cell. Middle lamella is the portion present between the primary cell wall of the nearby cell. There is a secondary cell wall and both are made up of cellulose and secondary cell wall is found within the primary cell wall and it also contains other components such as lignin.
Plasma membrane is elastic in nature and controls the movement of molecules. Endoplasmic reticulum, mitochondria, plastid, golgi bodies and ribosomes are the organelles found within the plant.
Plant Cell Diagram
Plants contain a nuclear envelope which has pores so that the required molecules can pass through and surrounds the nucleus. Within the nucleus are the chromosomes present and the exact number varies from plants to plant. Within the cytoplasm are located various organelles and the movement of cytoplasm is termed as cyclosis.
Animal Cell Diagram
The center most part of the cell which is the most important and huge in size is the nucleus, which is absent in red blood cells and abundant in skeletal muscle. Plants contain a nuclear envelope which has pores so that the required molecules can pass through and surrounds the nucleus.
Within the nucleus are the chromosomes present and the exact number varies from plants to plant. Through the nuclear pores the RNA, protein passes, which is an energy driven process when the cell receives the signals and the size of pores changes.
Chromatids are formed when the DNA and protein assemble in the nucleus and have function during cell division where they get condensed. The place where ribosomes gathers is the nucleolus and is found within the nucleus.
Synthesis of proteins from amino acid is the function of ribosomes and can be freely moving or attached to an organelle. In cases where it is attached, proteins are moved from lumen to ER to golgi bodies so that they are synthesized outside the cell or dispersed to organs. In the cytosol, those proteins are secreted which are not bound.
A net like structure which consist of tubules within the cytoplasm and the net like structure possess folding so that increases the surface are so that the enzyme can act. This is termed as endoplasmic reticulum.
It has two types: smooth and rough ER. Smooth ER lacks ribosomes whereas the rough ER possesses ribosomes. It functions are transport of intracellular protein, lipid and carbohydrate production, drug detoxification and regulation of calcium levels.
Golgi apparatus are found near the nucleus, although can be present in multiple number or as a single body within the cell. Its function is to sort proteins to the vesicles, which will transfer it to various organelles.
There is another organ found between the plasma membrane and golgi body it is the endosomes, which have tubule like shape. The vesicle traffic is cleared by them and is done by either fusing with them or pinching them.
The powerhouse of the cell is the mitochondria, which synthesizes energy called the ATP. Mitochondria possess two layers; outer one is smooth in nature and the other layer is folded to form cristae. There exists a type of DNA called the mitochondrial DNA, which the individual gets from their mother. Active cells require more mitochondria than the ones which are not that active.
Lysosome, the extremely acidic fluid, have functions in the immune system. They metabolize bacteria and their debris due to the presence of enzymes in their fluid.
The single membrane organ is the peroxisomes, which maintains the homeostasis and uses oxygen and excretes the hydrogen in the hydrogen peroxide form.
The part which allows the movement of bacteria, plants and animals and changes its shape are the filamentous proteins called the cytoskeleton.
Cytoskeleton is made of three filaments and are the Microfilaments which are formed from actin protein which readily construct and deconstruct. They are present in bountiful amount and are very thin. Microtubules as the name says they are in the form of tubules and are shallow.
In the nerve cells axons are these microtubules present and are very strong. They have a center region called the centrosome encapsulates the centrioles and contains a group of 9 microtubules.
Intermediate filaments are present in those places where the cells are in stress. They do not have the ability to construct and deconstruct themselves.
The process of photosynthesis is not possible without this organ. Stroma is present in the matrix of the chloroplast. Within the stroma lies the thylakoids which forms a pile of coins, which plays a role in the photosynthesis process. Chloroplast as well have their own DNA but are semi-autonomous.
Organelle which has a membrane called tonoplast is the vacuole along with cell sap which contains pigments and other substance. Vacuoles occupy a large position around 90%, for a single vacuole.
The division of cell is known as cell cycle and in the interphase lies the inactive cell, which has three divisions. Mitosis has four phases and after the mitosis the division takes place in active part of the cell which is the meristems.
The stages of mitosis are: Prophase where the outer envelope dissociates and the double stranded chromosomes are seen. In metaphase, they assemble at the center of the cell and spindle fiber is formed. The chromosome dissociates as the sister chromatids move apart from each other to form daughter chromosome and moves to cell’s end.
They form a covering called the nuclear envelope and have separate nucleus and thus two separate daughter cells are formed.
Plant Cell vs Animal Cell Citations
- Centrosome function and assembly in animal cells. Nat Rev Mol Cell Biol . 2015 Oct;16(10):611-24.
- Plant cell culture technology in the cosmetics and food industries: current state and future trends. Appl Microbiol Biotechnol . 2018 Oct;102(20):8661-8675.
- Plant cell wall-mediated immunity: cell wall changes trigger disease resistance responses. Plant J . 2018 Feb;93(4):614-636.
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Molar Mass: Definition, Calculation, and Examples
Continue ReadingWhat is Molar Mass?
Molecules and atoms are very minute, both in size and mass.
The molar mass is defined as the weight of one sample mole.
Relative molar mass is referred to as the smallest mass unit of a compound of one-twelfth of the mass of one carbon – 12 atoms.
The amount of entities present in a particular substance such as atoms, molecules, ions, is defined as a mole.
A mole of any substance is written as 6.022×1023 molecules.
The molar mass of a substance which is also known as the molecular weight is defined as the sum of the total mass in grams of all the atoms that make up a mole of a particular molecule.
The unit of this quantity is expressed in grams per mole.
How to Find the Molar Mass for Compounds?
Compounds are defined as substances that are made up of more than one element. For instance, some general compounds include salt, glucose and acetic acid (or vinegar), etc.
For instance; the compound sodium chloride comprises of two elements which are, sodium and chlorine.
Molar Mass Formula
The molar mass of a compound is defined as the mass of an assumed substance divided by the quantity of substance present in the sample.
Molar Mass = Mass of given substance/amount of substance
The molar mass is an intensive property of the matter and it doesn’t depend upon the dimensions of the sample.
The SI unit of molar mass is kg/mol. Though, for ancient reasons molar masses are almost always expressed in g/mol.
Atomic Mass
The meaning of atomic mass, the mole, and molar mass are all directly or indirectly connected to carbon-12.
This results in two important facts mentioned below;
• The atomic mass of one atom of carbon-12 is precisely 12 atomic mass units or amu.
• The mass of one mole of carbon-12 atoms is also precisely 12 grams and its molar mass is accurately 12 grams per mole.
NOTE: The atomic mass and the molar mass of carbon-12 are statistically equal. They only differ only in SI units; atomic mass is commonly measured in atomic mass units, and molar mass is generally measured in grams per mole.
Mole Definition
In chemistry, the mole is a fundamental (SI) unit used to measure the amount of substance. This quantity is sometimes referred to as the chemical amount. A substance is something that has mass and occupies space.
The molar mass / molecular weight is truly the sum of the total mass in grams of the atoms present to make up a molecule per mole. The unit of molar mass is grams/mole.
How to Determine Molar Mass of a Compound?
To find the molar mass of NaOH.
In a given compound of NaOH, the molar mass of Na is equal to 23 g/mol, the molar mass of O is equal to 16 g/mol, and the molar mass of H is 1 g/mol.
Na+O+H = NaOH
23 g/mol+16 g/mol+1 g/mol= 40 g/mol
The molar mass of the given compound of NaOH is equal to 40 g/mol.
Molar Mass Calculation
The molar mass of a compound is frequently calculated by adding the quantity of atomic masses (in g/mol) of the given constituent atoms.
The property of the molar mass of a given component is just the mass in g/mol.
Though, molar mass also can be calculated by multiplying the mass expressed in amu by the molar mass constant.
For instance; Find the molar mass of hydrogen (H2), sulfur (S8) by using the Molar Mass Formula.
The molar mass of molecules of those elements is always equal to the molar mass of the given atoms multiplied by the number of atoms present in each molecule.
Hence,
Molar Mass of (H2) is equal to 2 × 1.00797(7) × 1.000000 g/mol = 2.01588(14) g/mol
Molar Mass (S8) is equal to 8 × 32.065(5) × 1.000000 g/mol = 256.52(4) g/mol
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Mole Concept: Definition, Calculation, and Examples
Continue ReadingWhat is Mole Concept
The mole concept is an appropriate method of expressing the amount of a substance.
Any measurement can be fragmented down into two parts – the numerical magnitude and the units that the magnitude given is stated in. For instance, the mass of a ball was measured to be 5 kilograms, the magnitude of this is ‘5’, and the unit is expressed in ‘kilogram’.
What is Mole?
The word “mole” was announced by the German chemist Wilhelm Ostwald in 1896, who derived this term from the Latin word moles that means a ‘heap’ or ‘pile.
In the arena of chemistry, a mole is defined as the amount of a substance that contains precisely 6.02214076 * 1023 ‘elementary entities’ of the given element.
The number 6.02214076*1023 is generally known as the Avogadro constant and is frequently represented by the symbol ‘NA’.
The elementary entities can be characterized in atoms, molecules, monoatomic/polyatomic ions, and other particles like electrons.
For example, one mole of a pure carbon-12 (12C) model will have a mass of precisely 12 grams and comprises of 6.02214076*1023 (NA) quantity of 12C atoms.
The number of moles of a substance in a given example can be denoted by the formula given below:
n = N/NA
n is defined as the number of moles of the substance (or elementary entity)
N is defined as the total number of elementary entities present in the sample,
NA is defined as the Avogadro constant.
The uniqueness of a substance is defined not only by the types of atoms or ions it comprises but by the quantity of each type of atom or ion.
For instance, water, H2O, and hydrogen peroxide, H2O2, are identical in their respective molecules as they both are composed of hydrogen and oxygen atoms. But a hydrogen peroxide molecule encompasses two oxygen atoms, contrasting to the water molecule, which contains only one oxygen atom, the two substances show distinct properties.
The mole offers a link between an easily measured macroscopic property such as bulk or mass, and enormously essential property, the number of atoms, molecules, and so on.
Atomic Mass and Molecular Mass
The atomic mass of an element is defined as the mass of one atom of the element that is expressed in atomic mass units (amu).
It accounts for plenty of the numerous isotopes of the element and allocates an average value to the mass of one atom of the given element.
The atomic mass of a carbon-12 atom is 12 atomic mass units or amu, whereas the atomic mass of a carbon-13 atom is 13 atomic mass units or amu.
The atomic mass of an element is crudely equal to the sum of all the protons and neutrons present in the nucleus of a given atom.
The molecular mass of an element is defined as the sum of the atomic masses of all the components present in an element.
This quantity is also denoted in terms of atomic mass units. Hence, the molecular mass of water is always equal to the sum of all the atomic masses of its constituents present which are hydrogen and oxygen.
The atomic mass of hydrogen is equal to 1.00794 amu and the atomic mass of oxygen is equal to 15.9994 or 16 amu.
Since water molecules comprise of 2 hydrogen atoms and only one oxygen atom thus, the molecular mass of H2O will be 18.0154 amu.
Molar Mass
The molar mass of a given substance is the total mass of one mole of that substance.
It is denoted in terms of ‘grams per mole (g/mol). Though, the SI unit of the above-mentioned quantity is kg/mol. Molar mass can be represented by the formula written below:
The molar mass of a Substance = (Mass of the Substance in grams)/(Number of Moles)
Gram Atomic Mass vs Gram Molecular Mass
The gram atomic mass of an element is defined as the mass of one mole of a specific element. Correspondingly, the gram molecular mass of a compound is defined as the mass of a single mole of a particular compound. Hence, the gram atomic mass of hydrogen is roughly around 1.007g and the gram molecular mass of water or H2O is nearly around 18.015g.
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Scientific Notation: Definition, Calculation, and Examples
Continue ReadingWhat is Scientific Notation?
Scientific notation is a more appropriate way of writing small or very huge numbers.
The scientific notation helps us to signify the numbers which are very huge or very small in a form of multiplication of single-digit numbers and 10 raised to the power of the particular exponent.
The exponent is positive if the number given is very large and it is negative if the given number is very small.
Scientific Notation Representation
The representation of scientific notation is given below;
a × 10b ; 1 ≤ a < 10
To express a number in scientific notation, move the decimal place to the right if the number given is less than zero or to the left if the given number is greater than zero.
For instance, in 456000, in this number the decimal present is after the last zero, therefore to express this in scientific notation, move the decimal to in between the numbers 4 and 5.
The decimal would move five places to the left to get 4.56 as per the representation of scientific notation mentioned above.
The number of times we move the decimal place develops the integer “b.” In the above-mentioned number, the decimal moved five times.
Therefore, the given number in scientific notation would be;4.56 × 105
Scientific Notation Examples
Few Examples of scientific notation are given below;
1. 0.0007 = 7 x 10-4
2. 0.0345 = 3.45 x 10-2
3. 1234000 = 1.234 x 106
4. 8000 = 8 x 103
Another way used to write this expression, is to use the alphabet E which represents “times ten to the power of.”
For instance:
Scientific notation for Avogadro’s number is also an example of scientific notation as shown above on a calculator. 6.02E23 which is the same as6.02 x 1023. This method is mostly used by computer programs and calculators.
Scientific notation enables us to compare between orders of magnitude given in the question.
For instance, 100000000 can be inscribed as 108 in scientific notation. the exponent here is positive. Likewise, 0.0000001 is a very small number and can be represented in scientific notation as 10-8, here the exponent written is negative.
Scientific Notation in Daily Life
Few examples of measurements where the scientific notation is useful are given below;
• The wavelength for violet light is 40-millionths centimeter which can be written in scientific notation as 4 × 10−5cm.
• Some black holes are measured by the number of solar masses they comprise. One black hole measured as 10,000,000 or in scientific notation as1.0 × 107 solar masses.
• A computer hard disk holds 4 gigabytes (about 4,000,000,000 bytes) of data. That is written in scientific notation as 4.0 × 109 bytes.
• Computer calculation speeds are frequently measured in nanoseconds. A nanosecond is equal to 0.000000001 seconds or can be written in scientific notation as 1.0 × 10−9 seconds.
Rules for Scientific Notation
To determine the power or exponent of 10, the following rules must be followed:
• The base must be 10
• The exponent should be a non-zero integer, which means it can be either be written in positive or negative integer
• The absolute value of the coefficient is either bigger than or equal to 1 nonetheless it should be less than 10.
• Coefficients can either be positive or negative figures including whole and decimal numbers.
Positive and Negative Exponent of Scientific Notation
When the scientific notation of any huge numbers is stated, then use the positive exponents for base 10.
For instance: 80000 = 8 x 104, where 4 is expressed as the positive exponent.
When the scientific notation of any small numbers is stated, then the use of negative exponents is used for base 10.
For instance: 0.0006 = 6 x 10-4, where -4 is expressed as the negative exponent.
In simple terms, it can be said that the number larger than 1 can be written as the expression with a positive exponent, while the numbers which are less than 1 can be expressed with a negative exponent.
Scientific Notation Question
Question 1: Convert 0.00000089 into scientific notation.
Solution: We have to move the decimal point to the right of the number 0.00000089 up to 7 places.
The decimal point thus moved 7 places to the right to form figure 8.9
Since the numbers given are less than 10 and the decimal is thus moved to its right.
Therefore, a negative exponent is used here.
⇒ 0.00000089 = 8.9 × 10-7
The above mentioned number is thus written in scientific notation.
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Percentage Composition: Definition, Calculation, and Types
Continue ReadingWhat is Percentage Composition?
The percentage composition of any given compound is defined as the ratio of the amount of each element present in the given compound to the total amount of individual elements present in that particular compound multiplied by 100. The importance of this composition calculation is found in the chemical analysis.
Percentage Composition Formula
The percentage composition of a given element can be expressed by using the formula given below:
% of an element = (mass of element/molecular mass) x 100
The reason that we multiply this ratio by 100 is to get the percentage form of the given composition.
Percent composition is calculated from a molecular formula that is by dividing the mass of a single element in one mole of a compound by the mass of one mole of the whole given compound. This value is presented in the form of a percentage.
How to Calculate Percentage Composition?
Calculate the percent composition of each element in water.
The chemical formula for water is written as H2O and The molar mass of Oxygen is = 16.00 × 1(one molecule of oxygen is present in water) = 16 g/mole and the molar mass of Hydrogen is = 1.01 × 2(2 molecules of hydrogen are present in water) = 2.02 g/mole
Now, with the help of the molar mass of each of the given elements, find the percentage composition of each element present in H2O.
It is defined as the ratio of the grams of the element to the grams of the total element in that particular compound, multiplied by 100.
Thus, calculating the percentage composition of Hydrogen,
% H = 2.02/18.02 × 100
Consequently,
% H= 11.21 %
The percentage composition of Oxygen is calculated, So,
% O = 16/18.02 ×100 = 88.79 %
Mass Percentage Composition
The concept of mass percentage composition is used to represent the concentration of an element in a compound or the concentration of a component in a given mixture. We use this term to indicate the total percent by mass of each element that is present in a given compound.
The mass percentage composition can be calculated by dividing the mass of a component by its the total mass of the mixture. This ratio obtained is then multiplied by 100.
Importance of Mass Percentage
For many technical and scientific reasons, it is important to know what quantity of an element is present in an assumed compound.
This is crucial for pharmacists to get to the empirical formula of some compounds.
This formula also helps in displaying the lowest whole number of moles and the relative quantity of atoms of each element present in a particular compound.
With the help of this empirical formula, pharmacists can also calculate the actual molecular formula which shows the exact number of atoms present in the given compound.
Determining the Mass Percent from a Chemical Formula
Calculate the mass percent of glucose.
The chemical formula for glucose is written as C6H12O6. Now, calculate the mass percent of each of the elements present in glucose.
From the formula mentioned above, it can be observed that Glucose consists of 6 carbon atoms, 12 hydrogen atoms, and at last 6 oxygen atoms. Now multiply each of the atoms present in the glucose molecule by its molar mass.
So, 6 moles of carbon have 12.01g/mol x 6 = 72.06g of Carbon. (1 mole of carbon has a mass of 12.01grams)
Consequently, 12 moles of Hydrogen will have a mass of 12 x 1.008 = 12.096g of Hydrogen. (1 mole of hydrogen has a mass of 1 gram)
Thus, 6 moles of oxygen will have 16.00 x 6 = 96 g of Oxygen. (1 mole of oxygen has a molecular mass of 16 gram)
Hence, 1 mole of glucose (C6H12O6) has a total mass of (adding all the above values); 72.06 +12.096 + 96 = 180.16 g/mol
Percentage Composition Citations
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What is Limiting Reagent? How to Calculate...
Continue ReadingWhat is Limiting Reagent?
Limiting reagent in a reaction is the first to be fully used up and thus stops any further reaction from occurring.
In a given chemical reaction, the limiting reagent, or it is also known as limiting reactant, is the substance that has been fully consumed when the chemical reaction is completed.
With the help of stoichiometry, the exact amount of reactant which is needed to react with another element can be calculated.
Though, if the reagents are not mixed or are present in these precise stoichiometric proportions, then the limiting reagent will be fully consumed and the given reaction will not go to stoichiometric completion.
Thus, in simple terms, the reactant that is fully used up in a reaction is called a limiting reagent.
This reactant called limiting reagent generally governs when the reaction will stop.
The exact amount of reactant which will be required to react with another element can be calculated from the reaction stoichiometry.
The limiting reagent depends only on the mole ratio, not on the masses of the reactants present in the given chemical equation.
1. Limiting Reagent Examples
The formation of ammonia or NH3
3H2 + N2 → 2NH3
In the reaction given above, 3 moles of Hydrogen gas are reacted with 1 mole of nitrogen gas to form 2 moles of ammonia but from the above-mentioned balanced chemical equation, one mole of N2 requires only three moles of H2.
Thus, the limiting reagent in the above-mentioned reaction is H2.
2. Limiting Reagent Examples
Given below is another example of limiting reagent; Assume 1 mol of oxygen and 1 mol of hydrogen are present in a chemical reaction.
The following equation for the same is given below;
2H2 + O2 → 2H2O
Since the above reaction uses up hydrogen twice as fast as oxygen, the limiting reactant, in this case, would be hydrogen.
How to Find Limiting Reagent?
In most limiting reactant stoichiometry problems, the actual purpose is to determine how much product could be formed from a specific reactant mixture.
Thus, the limiting reactant or reagent can be determined by two methods mentioned below;
1. By using the mole ration
2. Using the product approach
First, to calculate the mass of the product, write the balanced equation and then find out which reagent is present in excess quantity. Then, by using the limiting reagent calculate the mass of the product formed in a chemical reaction.
1. How to Identify Limiting Reagent?
The following points given below should be considered while trying to identify the limiting reagent:
• When only two reactants are given in a chemical reaction, first write the balanced chemical equation and then check the amount of reactant B which is required to react with the given reactant A. When the quantity of reactant B is greater, then reactant A is the limiting reagent in that particular reaction.
• The reactant which is present in a lesser amount in a chemical reaction than required by stoichiometry is thus the limiting reactant.
• In another method of finding the limiting agent is by calculating the amount of product formed by each reactant.
• The limiting reactant is the reactant from which the least amount of product is formed in a chemical reaction Thus, the required limiting reagent for the reaction can be recognized using the points mentioned above. These reagents are a vital part of a chemical reaction while calculating the percentage yield of a given chemical reaction.
2. How to Identify Limiting Reagent?
We can also find the limiting reagent by observing the number of moles of each reactant in a given chemical equation.
Steps are mentioned below;
1. Firstly, determine the balanced chemical equation for the given chemical reaction.
2. Then, convert all given data into moles (most probably, with the use of molar mass as a conversion factor).
3. Now, calculate the mole ratio from the given data. Then, compare the calculated ratio to the actual ratio.
4. Use the amount of limiting reactant thus, to calculate the amount of product formed in the chemical reaction.
5. If needed, calculate how much is left in the surplus of the non-limiting reagent.
Limiting Reactant and Theoretical Yield
A reactant in a chemical reaction can also limit the quantities of products formed by the given reaction. When this occurs, we refer to the reactant as the limiting reactant (or limiting reagent) and the amount of a product formed when the limiting reactant is entirely consumed in a reaction is known as the theoretical yield.
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What is Stoichiometry? Definition, Calculation, & Worksheet
Continue ReadingWhat is Stoichiometry?
In simple words, Stoichiometry is defined as the calculation of products and reactants in a given chemical reaction. It is principally concerned with numbers.
The word “ stoichiometry” originated from the Greek word “stoikhein” which means element and the word “metron” means to measure.
This term Stoichiometry was first proposed by a well-known German chemist Jeremias Richter.
Stoichiometry is a significant concept in chemistry that helps us balanced calculate the quantities of reactants and products in a given chemical equation.
For instance, oxygen and hydrogen react to form a substance called water in which one mole of oxygen reacts with two moles of hydrogen and hence forms two moles of water.
In addition to this, stoichiometry can also be used to find quantities such as the amount of products that can be formed with a given quantity of reactants and percent yield.
Importance of Stoichiometry
Stoichiometry helps us govern how much substance is needed or is present in the given compound.
Things that can be measured using stoichiometry are;
1. Reactants’ mass and Products mass
2. The molecular weight of a given compound
3. Chemical equations
4. Formulas of different compounds or elements
Stoichiometric Coefficient or Stoichiometric Number
Stoichiometric coefficient or stoichiometric number is defined as the number of molecules that participate in the given chemical reaction. A balanced equation has an equal number of elements on both sides. The stoichiometric coefficient is mostly the number that is present before atoms, molecules, or ions.
Stoichiometric coefficients can be in the form of fractions as well as whole numbers. In addition to that, the stoichiometric coefficients help to establish the mole ratio between reactants and the products of a given chemical equation.
Stoichiometry in Chemical Analysis
Stoichiometric calculations follow a numerical analysis methodology that is frequently used by pharmacists to determine the concentrations of materials present in a given sample.
There are chiefly two main types of analysis given below;
1. Gravimetric Analysis
Gravimetric analysis describes the numerical determination of the analyte based on the mass of the given solid compound.
The gravimetric analysis gives the most precise results as compared to other analytical analyses Gravimetric analysis can be categorized into the following types mentioned below;
1. Precipitation gravimetry involves isolation of ions in a given solution by a precipitation method then filtering, washing the precipitate, and lastly weighing the precipitate and determining its mass by difference.
2. Volatilization gravimetry involves separating components of a mixture either by heating or chemically decomposing the given sample.
3. Electrogravimetry involves the electrochemical reduction of metal ions at the cathode and the immediate deposition of ions on the cathode.
This cathode is weighed before and after the electrolysis is done and the weight, difference thus parallels to the mass of analyte primarily present in the given sample.
2. Volumetric Analysis
The volumetric analysis involves the numerical measurement of a substance in terms of its volume.
In volumetric analysis, a known volume (V1) of the given substance whose concentration (N1) is known is made to react with the unknown volume (V2) of the given solution of the substance whose concentration(N2) is to be calculated. The volume, V1 is defined as the endpoint of the reaction.
Thus, the concentration N2 is calculated with the help of following equation mentioned below;
N1x V1 = N2 x V2
The endpoint of such a reaction is directed by a change in a color with the help of indicators or precipitation etc.
Stoichiometric Values in a Chemical Reaction
In some cases, it might be necessary to calculate the number of moles of a reagent or product under certain given conditions. To do this properly, the reaction needs to be balanced.
The law of conservation of matter thus states that the quantity of each element does not change in a given chemical reaction. Consequently, a chemical equation is balanced to make the quantity of each element in the equation the same.
Chemical reactions are balanced by adding coefficients in front of the given reactants and products.
Example: Balance the given equation;
N2 + O2 → NO
The given equation is not considered balanced since there are more N and O atoms on the left side of the equation as compared to the right side or product of the reaction. Allocate a stoichiometric coefficient of 1 to the given compound, NO.
N2 + O2 → 1NO
Now, balance the remaining element. To do this, we used fractional coefficients.
1/2N2 + 1/2O2 → 1NO
To get rid of the fractional coefficients multiply the reactants by 2 to this equation balanced.
N2 + O2 → 2NO
Thus, the above equation is balanced.
Limiting Reagent
In a chemical reaction, if any one of the reactants is present in a surplus amount then some of these excess reactants will, consequently, be left over when the given reaction is completed.
The given reaction will stop instantly as soon as one of the reactants is fully consumed. The substance that is fully consumed in a given reaction is known as a limiting reagent.
Example;
N2 + 3H2 ➝ 2NH3
Assume we have one mole of N2 that reacts with one mole of H2. But from the above-mentioned balanced chemical equation, one mole of N2 requires only three moles of H2. Thus, the limiting reagent in the above reaction is H2.
Stoichiometry Citations
- “Why not stoichiometry” versus “Stoichiometry–why not?” Part II: GATES in context with redox systems. Crit Rev Anal Chem . 2015;45(3):241-69.
- Stoichiometry and physical chemistry of promiscuous aggregate-based inhibitors. J Am Chem Soc . 2008 Jul 23;130(29):9606-12.
- Determining the stoichiometry and interactions of macromolecular assemblies from mass spectrometry. Nat Protoc . 2007;2(3):715-26.
- Defining the stoichiometry and cargo load of viral and bacterial nanoparticles by Orbitrap mass spectrometry. J Am Chem Soc . 2014 May 21;136(20):7295-9.
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What is Atomic Mass? How to Find...
Continue ReadingWhat is Atomic Mass?
A property that is thoroughly related to an atom’s mass number is its atomic mass. T
he atomic mass of a single atom is basically defined as its total mass and is naturally expressed in its atomic mass units or is also called as amu.
In other words, an atom of carbon has six neutrons, carbon-12, with an atomic mass of 12 amu.
In general, however, an atom’s atomic mass is very close to its given mass number but will have some deviation in its decimal places.
Since an element’s isotopes have different atomic masses, researchers may also govern the relative atomic mass which is sometimes called as the atomic weight of an element.
The relative atomic mass is defined as an average of the atomic masses of all the different isotopes present in a sample.
Celestial objects such as asteroids or meteors may have a very different isotope abundance.
How to Find Atomic Mass?
The figure given below explains how to find atomic mass and atomic number from a given element;
Atomic Mass Definition
Atomic mass is defined as the total mass of an atom. For example; the mass of 12C (carbon twelve) is inscribed as 12 amu.
All the masses of the elements are determined with 12C.
Periodic Table With Atomic Mass
The figure (periodic table with atomic mass) below shows the atomic mass of some of the frequently used elements;
What is Atomic Number?
The atomic number of an element describes the element’s identity and indicates the number of protons present in the nucleus of that particular atom.
For instance, the element hydrogen always has one proton present in its nucleus. The element helium always has two protons present in its nucleus.
Similarly, from the above figure element molybdenum have 42 protons present in its nucleus.
Atomic Mass and Isotopes
Atoms of the same element can, have different numbers of neutrons present in their nucleus.
For any assumed isotope, the summation of the numbers of protons and neutrons in the nucleus is known as the mass number.
This is because each proton and each neutron present in the nucleus weigh one atomic mass unit (amu).
By totaling together the number of protons and neutrons and multiplying it by 1 amu, we can calculate the mass of the given atom.
The word ‘isotope’ originates from the Greek word ‘isos’ which means ‘same’ and ‘topes’ means ‘place’.
Thus the name isotopes to given to elements having the same number of protons because these elements can occupy a similar place on the periodic table while being different in their subatomic construction.
For instance, Carbon exists as two main isotopes, 12C, and 14C carbon atom which has the same number of protons and electrons, 12C has 6 neutrons, and 14C has 8 neutrons and is a radioactive isotope.
Isotopes Types
• Few isotopes do have unstable atomic nuclei that undergo radioactive decay. Particularly these isotopes are radioactive and are, consequently, known as radioisotopes or radionuclides.
Examples for the same include carbon-14, chlorine-36, uranium-235, and uranium-238, etc.
• Some isotopes are identified to have tremendously long half-lives (hundreds of millions of years of life). Such isotopes are generally stated as stable nuclides or stable isotopes.
Some examples for the same include carbon-12, carbon-13, oxygen-17, and oxygen-18, etc.
• Primordial nuclides are defined as the nuclides that have existed since the formation of this solar system.
Out of 339 naturally occurring isotopes present on the Earth, a whole of 286 isotopes are recognized to be primordial isotopes.
Why Atomic Mass is Useful?
The atomic mass is beneficial in chemistry when it is connected with the mole concept.
The atomic mass of an element that is measured in amu, is similar as the mass present in grams of one mole of an element.
For instance, the atomic mass of iron is 55.847 amu and one mole of iron atoms also weigh 55.847 grams.
Atomic Mass Citations
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What is Law of Conservation of Mass?...
Continue ReadingHistory of Law of Conservation of Mass
The ancient Greeks initially proposed the idea that the total sum of matter in the universe is always constant. Though, Antoine Lavoisier stated the law of conservation of mass as a vital principle of physics in 1789.
What is Law of Conservation of Mass?
The Law of Conservation of Mass states that matter can neither be created nor it can be destroyed in a given chemical reaction. Thus, the total mass of reactants is always equal to the total mass of products.
This law of conservation of mass also stated that the mass of the system cannot change over a period of time in a closed system.
Law of Conservation of Mass example; the burning of a candle, a candle is made up of wax, thus When the lit candle, the oxygen gas present in the room will react with the candle wax to produce water vapor and carbon dioxide gas.
Thus the mass of reactants which are oxygen and wax will be equal to the mass of the products which are water and carbon dioxide.
The matter changes from one form to other but the mass of the matter always remains the same before and after the change.
For instance, if 44 grams of reactants go into a given chemical reaction, then 44 grams of products are being produced.
Law of Conservation of Mass Importance
The Discovery of this law of conservation of mass assisted to turn chemistry into the reputable science it is today.
With the initiation of this law of conservation of mass, chemists brought certainty and consistency to the science of chemistry.
If scientists know the quantities and characteristics of reactants for a specific reaction, then they can foresee the amounts of products that will be formed.
Law of Conservation of Mass Examples
I. Combustion Process
The burning of wood is an example of conservation of mass as the burning of wood comprises of production of gases such as Oxygen, Carbon dioxide, and water vapor, ashes.
II. Chemical Reactions
Water, for instance, comprises of two hydrogen atoms and one oxygen atom. Water is the only known substance on Earth that occurs naturally in three states: solid, liquid, and gas.
For water to change amongst these states, it must undergo physical changes. Thus, when water freezes, it changes into this hard and less dense substance known as ice, but the number of water molecules present before and after the change remains chemically the same.
Water gives a very vibrant example of how the cycle of matter works through our world, often changing form but never vanishing.
Both hydrogen and oxygen are diatomic atoms means they occur naturally as bonded pairs (H2 and O2, correspondingly). In the precise conditions and with an adequate amount of energy, these diatomic bonds will break and the atoms present individually will combine to form H2O (water).
The chemical equation can be written as:
2H2 + O2 = 2H2O
Note: There is the same number of hydrogen atoms and oxygen atoms on both sides of the equation that is reactants are always equal to the products.
III. Photosynthesis
Another Example of the same include Photosynthesis. In this process of photosynthesis, the plants convert light energy from the sun into chemical energy and store it in the form of sugars.
Although, light energy simply provides some energy for a chemical change to occur. The atoms required for photosynthesis are derived from carbon dioxide present in the air and water in the soil.
Then rearranges the atoms and the molecules into glucose C6H12O6 and oxygen O2.
6CO2 + 6H2O + sunlight = C6H12O6 (sugar or carbohydrates) + 6O2
This equation states that the six-carbon dioxide molecules combine with six water molecules thus forming one sugar or carbohydrate molecule and six molecules of oxygen.
By totaling or adding all the carbon, hydrogen, and oxygen atoms on both sides of the equation, the number of atoms or molecules would be equal.
Thus, the matter is preserved in this chemical change as well.
Law of Conservation of Mass Citations
- Scaling and scale invariance of conservation laws in Reynolds transport theorem framework. Ann Sci . 2015 Apr;72(2):153-69.
- The conservation of matter. Ann Emerg Med . 2002 Jan;39(1):91-3.
- The application of mass and energy conservation laws in physiologically structured population models of heterotrophic organisms. J Theor Biol . 1999 Apr 7;197(3):371-92.
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