Category: Chemistry
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Avogadro’s Law: Formula, Calculation, Definition, and Examples
Continue ReadingAvogadro's Law
In 1811, Avogadro’s law was described by a famous Italian chemist and physicist named Amedeo Avogadro. Avogadro’s law is a relationship between volume of gas and the number of moles.
This law states that at a constant temperature and pressure the total number of atoms or molecules present in a gas is directly proportional to the volume occupied by that gas.
Avogadro's Law Formula
This equation is given by;
V ∝ n
V=kn or k = V/n
V = volume of gas
n = Number of moles present in given gas
k = proportionality constant
The graphical representation of Avogadro’s law is given below;
The straight line indicates that the two quantities that are volume and number of moles present in gas are directly proportional to each other.
Thus, the straight line that passes through the origin signifies that 0 moles for gas will occupy zero space.
Avogadro's Law Calculation
Avogadro’s law can be derived from the ideal gas equation, which can be written as follows:
PV = nRT
• ‘P’ is defined as the pressure applied by the gas on the walls of container
• ‘V’ is defined as the volume occupied by the gas
• ‘n’ is defined as number of moles of gas present in given molecule
• ‘R’ is defined as the universal gas constant
• ‘T’ is defined as the absolute temperature of the gas
By reorganizing the ideal gas equation, the following equation can be obtained.
V/n = (RT)/P
Here, the value of (RT)/P is constant because pressure and temperature are constant according to Avogadro’s hypothesis and R is the universal constant.
Therefore,
V/n = k
Thus, the proportionality between the volume occupied by a gas and the number of molecules present in given gas is confirmed.
Avogadro’s Law Examples
Given below are few examples of Avogadro’s law;
I. Breathing
One of the finest example of Avogadro’s law is breathing. When we inhale, our lungs enlarge because they are filled with air. Similarly, when we exhale, the lungs let the air out and thus shrink in size. This change in volume is observed, which is proportional to the amount or the number of molecules of air confined by the lungs.
II. Inflating Tyres
The shape of a flat tyres gets distorted in the absence of air inside it. As soon as the flat tyres is filled with the required amount of air, it gets back to its original shape. Hence, the inflation of flat tyres is a clear example of Avogadro’s law in our everyday life.
III. Bicycle Pump Action
The pump abstracts the air from the environment and pushes it inside a flattened object. This increase in the amount of gas molecules in the object congruently changes its shape and helps it to enlarge. This example is clearly explained by Avogadro’s law.
IV. Pool Tube
A flattened pool tube becomes transportable as the number of air particles inside the tube is decreased which in turn reduces its volume and makes it compact.
During inflation, when the tube is filled with air, increasing the number of air molecules in it which in turn increases the volume and size of the pool tube. Henceforth, Avogadro’s law can be applied to inflate or deflate the given pool tube as per our necessity.
Avogadro's Number
Avogadro’s number is defined as the number of molecules of gas present in one mole that is huge (6.02×1023).
The unit for Avogadro number is mole-1.
Avogadro’s number is generally symbolized by N.
Avogadro’s number is a unit used by chemists for easy calculations all over the world.
Significance of Avogadro’s Law
After realizing that the volume of a gas is directly proportional the number of particles present in the gaseous molecules, this formula established a vital relationship for simple molecules at that time when the distinction between atoms and molecules was not visibly understood.
Specifically, the existence of diatomic molecules such as that H2, O2 and Cl2 was not identified until the results of researches involving the volume of gas molecules was discovered.
Limitations of Avogadro’s Law
This law is also known as Avogadro’s principle or Avogadro’s hypothesis. This law is only relevant to ideal gases and gives an estimated result for the real gases.
The gases with light molecules for instance helium, hydrogen, etc., follow Avogadro’s law more precisely as compared to the gases with heavy molecules.
Avogadro's Law Citations
- AVOGADRO’S LAW AND THE ABSORPTION OF WATER BY ANIMAL TISSUES IN CRYSTALLOID AND COLLOID SOLUTIONS. Science . 1913 Mar 21;37(951):427-39.
- Avogadro’s Hypothesis (or Law). Nature volume 82, page338 (1910)
- AVOGADRO’S LAW AND THE ABSORPTION OF WATER BY ANIMAL TISSUES IN CRYSTALLOID AND COLLOID SOLUTIONS. Science 21 Mar 1913: Vol. 37, Issue 951, pp. 427-439
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Threshold Frequency: Definition, Equation, and Examples
Continue ReadingThreshold Frequency Definition
The threshold frequency is defined as the minimum frequency of the incident radiation below which photoelectric emission or emission of electrons is not possible.
The threshold frequency refers to the frequency of light that will cause an electron to dislodge emit from the surface of the metal.
If γ signifies the frequency of incident photon and γth signifies threshold frequency, then;
• If γ < γTh, then this denotes that no ejection of photoelectron will occur.
• If γ = γTh, then this denotes that photoelectrons are just ejected from the surface of the metal, however, the kinetic energy of the electron is equal to zero.
• If γ > γTh, then this denotes that the photoelectrons are ejected from the metal surface. Photoelectrons ejected have some kinetic energy.
These trends are thus termed as the photoelectric effect.
Kinetic energy (K.E) is equal to half times the mass (or abbreviated as m) multiplied by the square of the velocity (or abbreviated as v) of the electrons as shown below;
K.E = 1/2 (mv2)
Photoelectric Effect
The photoelectric effect is referred to a phenomenon in which electrons are expelled or ejected from the surface of a metal when light is incident on it. Electrons thus emitted are also termed as photoelectrons.
Therefore, the threshold frequency is referred to as the frequency of the light which carries sufficient energy to extricate an electron from an atom.
According to Albert Einstein, the photoelectric effect is described as follows:
Thus,
hν = W + E
Where
• h signifies Planck’s constant.
• ν signifies the frequency of the incident photon.
• W signifies a work function.
• E signifies the maximum kinetic energy of ejected electrons: 1/2 mv².
The Work Function
The work function of a metal is referred to as the minimum amount of energy which is required to start the emission of electrons from the surface of the metal. The work function is expressed in electron volts. One electron volt is referred to as the energy required to move an electron across a potential difference of one volt. Different metals have characteristic work functions, and also distinctive threshold frequencies.
For instance, aluminum has a work function equal to 4.08 eV, however, potassium has a work function equal to 2.3 eV.
1eV = 1.6 x 10-19 Joule
Photons
A photon can be defined as a quantum of light that has zero rest mass and moves at the speed of light in the vacuum. The phenomena of the photoelectric effect cannot be defined by considering light as a wave. Though, this effect can be described by considering the particle nature of light, which further states that light can be imagined as a stream of particles of electromagnetic energy. Hence, these particles of light are termed as photons.
The energy held by a photon is as follows;
E = h𝜈 = hc/λ
Where,
• E signifies the energy of the photon
• h signifies Planck’s constant
• 𝜈 signifies the frequency of the light
• c signifies the speed of light (in a vacuum)
λ signifies the wavelength of the light
Work Function and Threshold Frequency Formula
The theory of the photoelectric effect was proposed by Einstein by using Max Planck’s theory of light energy. It was thus considered that each packet of light energy (or commonly called as photons) carried energy equal to hv where h represents a proportionality constant known as the Planck constant and v represents the frequency of the electromagnetic waves of light.
Kmax represents the maximum amount of kinetic energy carried by the atoms before leaving their atomic bonding.
To describe the threshold frequency the equation for the photoelectric effect can be written as follows:
Kmax = hv-W
Where,
W represents the work function of the metal. It is defined as the minimum energy that needs to be supplied to the metal body for the discharge of photoelectrons.
Now W can be written as follows:
W = hvo
Here
vo represents the photoelectric threshold frequency of the electromagnetic radiation.
Threshold Frequency Applications
The concepts of threshold energy in photoelectric effect and threshold frequency find their application in several devices and processes. Some of which are as follows;
• Photoelectron Spectroscopy: Photoelectron spectroscopy measurements are often done in a high vacuum environment to avert the electrons from being dispersed by gas molecules that are present in the air. In this process, we use monochromatic X-rays or UV rays of known frequency and kinetic energy (K.E) to determine experimentally the composition of given area samples.
• Night Vision Devices: When Photons strike alkali metal or semiconductor material (such as gallium arsenide) in an image intensifier tube, then this causes the expulsion of photoelectrons because of the phenomena known as the photoelectric effect. This is further accelerated by an electrostatic field where electrons strike a phosphor-coated screen hence converting electrons back into photons. Signals are thus produced and intensified due to the acceleration of electrons. This concept which is mentioned here is used in night vision devices.
• Image Sensors: Television in the early days contained video camera tubes that made use of the photoelectric effect to convert an electronic signal into an optical image. Though, presently, the mechanism of television working has been reformed.
The concept of photoelectric emission, work function, and photoelectric threshold frequency are essential to understand quantum physical sciences. This is also required for constructing various devices and to study various other phenomena.
Threshold Frequency Examples
Q. Calculate the threshold frequency for a metal with a work function of 5 electron volt or eV?
Solution: The equation for work function is given as-
W = hvo
vo = W/h
Where h represents Planck’s constant
vo represents the threshold frequency of metal
Converting 5eV into Joules as we know
1eV = 1.6 x 10-19 Joule
So, 5 eV = 5 x 1.6 x 10-19 Joule
vo = (5 x 1.6 x 10-19) / (6.63 x 10-34)
Thus,
vo = 1.20 x 1015 Hertz or Hz
Threshold Frequency Citations
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Examples of Physical Properties: Definition, Meaning
Continue ReadingExamples of Physical Properties
Changes can be categorized into physical and chemical. The matter is made up of tiny particles and has both the properties which are;
A chemical property is defined as the characteristic of a substance that can be observed in a chemical reaction.
For example heat of combustion, toxicity, acidity, reactivity etc.
A Physical Property is defined as the characteristic of a substance that can be observed without changing the chemical nature of the substance such as its size, state of matter, colour, mass, density etc. Some other physical properties include solubility, melting and boiling points etc.
Classification for Physical Properties
There are two classes of physical properties which are;
1. Extensive Property
2. Intensive Property
1. Extensive Property
Extensive properties are those properties that depend on the size of the sample.
Shape, volume and mass are extensive properties. The properties like length, mass weight and volume that not only depend on the size but also depend on the quantity of the matter.
For instance, if we have two boxes made up of the same material one has the capacity of 6 litres and the other has the capacity of 12 litres then the box with 12-litre capacity will have more amount of matter as compared to that of the 6-litre box.
2. Intensive Property
Intensive properties are those properties that do not depend on the size or amount of matter in the sample.
Temperature, pressure and density are some of the examples of intensive properties other examples include colour, melting and boiling points as they will not change with the change in size as well as quantity of matter.
The density of 1 litre of water or 1000 litre of water will remain the same as it is an intensive property.
Physical Change
Physical change takes place without any changes in the molecular composition of the substance. The same molecule is present in the substance throughout the changes.
Physical changes are related to the physical properties of a substance which are solid liquid and gas.
During physical change the composition and the chemical nature of matter are not changed chemical property is not affected by the physical change of a substance.
The physical change includes a change in colour, solubility, change in the state of matter etc.
Examples of physical change include melting an ice cube, dissolving sugar and water. Boiling water is also an example of physical change because the water vapour has the same molecular formula as that of liquid water.
Use of Physical Properties
Physical property is used to determine the appearance, texture, colour etc. of a substance thus, these physical properties are important as they help us to differentiate between different compounds, unlike chemical properties which help us to differentiate between various compounds only when a new substance is formed from a given substance by chemical reactions.
Examples of Physical Properties
A few examples of the physical property of matter comprise of;
• Malleability occurs when metal is moulded into thin sheets, for instance, silver is shiny metal and it can be moulded into thin sheets.
• Hardness which is another physical property helps to determine how the element can be used. For Example; Carbon in diamonds is very hard whereas carbon in graphite is very soft.
• Melting and boiling point is the physical property that is unique identifiers, especially of compounds
• Melting Point: When the solid matter is heated it ultimately melts or changes into its liquid state. The ice is a solid form of water that melts at 0 oC or 32 oF and changes to its liquid state that is water or H2O.
• Boiling Point: When the liquid matter is heated further it ultimately boils or vaporizes into its gaseous state. Liquid water boils and changes into gaseous molecules or water vapour at a temperature of 100 oC.
• Density implies the weight of the substance
Density is defined as mass divide by volume.
Density = Mass/Volume
• Colour is another physical reflective property of the given material. For example; Rusting of iron.
• Volume is referred to as a three-dimensional space that is occupied by a matter.
• Mass is one of the most significant fundamental property of an object and is defined as the measure of the amount of matter that is present in a body or substance.
• Weight is defined as the measure of the force of gravity acting on an object.
Examples of Physical Properties Citations
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Metric System Chart: Definition, Formula, and Calculation
Continue ReadingMetric System Chart
The metric system chart was introduced in the year 1790 in France and was the historical invention of the international system of units or SI units which is also known as metrification.
The various units of measurement lead to the introduction of the metric system.
Metric System
The metric system of measurement is the standard way of measuring distance, height, and many other day to day events.
Each object is measured according to its length, volume weight height, and time.
The three main basic units of the metric system are;
Metre: a unit used to calculate the length of an object.
Kilograms: a unit that is used to measure the mass of an object
Second: a unit of time.
Origin of the Metric System
Metrication is defined as a process that implements the international system of units called SI units. The Metric system is followed by nearly all countries except United States, Myanmar, and Liberia.
The United States further introduced its system of units or system of metric units which are now called the United States customary units.
Difference Between USCS and SI Units
The United States metric units are also called “imperial units.” The key difference between the SI units and the American metric units is the terms and the form of units used.
For instance, In the SI unit, the length is measured using the meter whereas In USCS foot is used for measurement.
Metric Conversion
Metric conversion has referred to the conversion of the given units to the chosen units for any given quantity that is to be measured. This metric system of measurement is a set of standard units that are defined to measure the length, weight, and capacity of the given object.
Metric Conversion Chart
Metric conversion charts help us in the conversion of given units to desired units. The metric conversion helps in easier and quick calculations.
Some metric chart tables are given below;
Length Conversion Chart
This unit length is used for measuring the size of an object or the distance that an object travels from one end to another end.
There are different units of length which are meters, kilometers, feet, etc. The basic tool which is used to measure length is called a ruler.
For Example; The height of this whiteboard is about 3 meters.
The smallest unit of measuring length is a millimeter and the largest unit of measuring length is kilometers.
Length conversion chart
1 inch = 2.54 cm
1 foot = 12 inch
1 yard= 3 feet or 36 inches
1 mile = 1760 yards
1 kilometer = 1000 metre
Weight Conversion Chart
Weight is the unit that is used to measure the mass of a substance. The standard unit that is used for the measurement of mass is the kilogram, gram ton, etc.
The basic tool which is used to measure the weight of an object is the weighing scale.
For instance; the weight of this alcohol bottle is 250 grams.
Weight conversion chart
1 kilogram =1000 gram
1 pound = 16 Oz
1 Oz = 16 drums
1 ton = 2,000 LB
Volume Conversion Chart
Volume is the unit that is used to measure the space occupied by an object or matter. The standard unit used for the measurement of capacity is litre. Other units used for measurement of unit volume are milliliter etc.
For example; 500 liters of juice.
Volume conversion chart
1 litre = 1000 ml
1 cup=250 ml
1 gallon = 4 watts
1 pint = 2 cups
Time Conversion Chart
The standard unit for the measurement of time is in seconds. Other metric units of time are minutes, hours, etc.
1 minute = 60 seconds
1 hour= 60 minutes
1 day = 24 hours
1 week = 7 days
Area Conversion Chart
The area is occupied by a two-dimensional figure the area is usually measured in square units.
1 acre= 43560 square feet
Metric System Chart Citations
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Volume: Definition, Formula, Chart, and Calculation
Continue ReadingVolume Definition
Volume is referred to as a three-dimensional space that is occupied by a matter for any other closed figure.
SI unit of volume is cubic meter (cm3) but many other units exist which include cubic centimeter, pint, quart, gallon, tablespoon, etc.
Examples of volume are; These beer bottle bottles hold 250 ml of alcohol.
Ishita drank 100 ml of water.
You can purchase a gallon of milk.
Volume of Liquid
The volume of a liquid can be measured with the help of a measuring container such as a measuring cup, graduated cylinders.
The volume of liquids is addictive but this is not always true because the volume of miscible liquids such as that of alcohol and water may be less than the sum of the separate volumes.
Another point to be noted is that dissolvable solids in two liquids don’t always result in their adjective volumes.
Volume of Gas
Volume of a gas is defined as the volume of its container as the gas expands to fill the space available to them in the given container.
The volume of a gas is sometimes determined by the displacement of its liquid.
Volume of Solid
The volume of a solid can be calculated by using its dimensions.
For example; the volume of a rectangular solid is the product of its length, width, and height that is V=lwh.
Volume vs Mass
The volume and mass are considered the same but these are two different properties of matter.
Volume is defined as the amount of space occupied by a substance on the other hand mass is the amount of matter contained in a substance.
Density is defined as mass per unit volume but it is possible to have volume without the mass the example for the same would be an enclosed vacuum.
Volume vs Capacity
Capacity and the volume of a container are not the same as capacity is defined as the capability of an object to contain a substance that is either solid, liquid, or gas, whereas volume is referred to the three-dimensional space that is occupied by the matter.
Volume is measured in cubic units such as in cubic centimeters and cubic meters etc.
Capacity is measured in metric units such as in liters, gallons, etc.
Charles Law
Charles law states that the volume of a certain amount of gas is directly proportional to that of temperature in kelvin when the pressure remains constant.
This can be written as;
V = kT
k = proportionality constant
V = volume of given gas
T = temperature of a given gas
Boyles Law
Boyle’s law states that the volume of a certain amount of gas is inversely proportional to its pressure when the temperature is kept constant.
The equation can be represented in the form of;
P = k/V
k = a proportionality constant
P = Pressure of given gas
V= volume of a given gas
Avogadro's Law
Avogadro’s law states that the volume is directly proportional to the number of moles of a given gas when the pressure and the temperature both remain constant.
The following equation can be written in the form of
V = kn
k = proportionality constant
n = Number. of moles of a given gas
V= volume of a given gas
Ideal Gas Law
The above four laws discussed are combined to produce an ideal gas law which is a relationship between pressure, volume, temperature, and the number of moles present in given gas.
The equation is given as
PV = nrt
P = pressure of the gas
V= volume of gas
N = number of moles of gas
T = temperature in kelvin
r = Constant and is also known as the ideal gas constant for the universal gas constant.
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International System of Units (SI Units): Chart,...
Continue ReadingInternational System of Units (SI Units)
International system of units (SI Units) is the most widely accepted system of measurement and this system is built on 7 primary units which are:
Length
Time
Weight
Amount of substance
Electric current
Temperature
Luminous intensity
This international system of units was earlier referred as meter-kilogram-second (MKS) system.
The principle behind international system of units is that it used to provide the same values across the world for measurements such as length, height, weight etc.
SI plays a vital role in international conferences and is also used in scientific and technological research.
History of SI Units
The international system of units was introduced in 1960 which was adopted by 11th general conference on weights and measure or CGPM.
This system was invented to modify the definition of units and to be used as technology for measuring objects that we use in our daily lives.
The United States further introduced its own system of units or system of metric units which is now called as United States customary units or USCS
Difference Between USCS and SI Units
The United States metric units are also called as “imperial units.” The key difference between the SI units and the American metric units is the terms and the form of units used.
For instance, In SI unit, the length is measured using the metre whereas In USCS foot is used for measurement.
The international system of units consisted of following three categories mentioned below; Base units Supplementary units Derived units
The seven base units are given below:
Length
This unit length is used for measuring the size of an object or the distance that an object travels from one end to the other end. There are different units of length which are metre, kilometers, feet etc. The most common tool which is used to measure length is called a ruler.
For Example; The height of this blackboard is about 3 metres. Smallest unit of measuring length is millimeter and the largest unit is kilometers.
1 kilometer = 1000 metre
Time
The standard unit for measurement of time is seconds. Other metric units of time are minutes, hours etc.
1 minute = 60 seconds
1 hour= 60 minutes
1 day = 24 hours
1 week = 7 days
Weight
Weight is the unit that is used to measure the mass of an object. The standard unit that is used for the measurement of mass is kilogram, gram ton etc.
The most common tool which is used to measure the weight of an object is the weighing scale. For instance; the weight of this bottle is 250 grams.
1 kilogram =1000 gram
Amount of Substance: Mole
The amount of matter of a system that comprises as many elementary entities as there are atoms in 0.012 kilogram of carbon 12. Elementary entities are subatomic units that comprise matter and energy.
The symbol of unit mole is mol.
Luminous Intensity
The luminous intensity, in given route, of a source produces monochromatic radiation of frequency 540×1012 hertz and has a radiant intensity in that path of 1/683 watt per steradian.
The unit of luminosity is candela which is denoted by cd.
Current
Electric current is well-defined as the rate of flow of negative charges of a conductor. Since the charge is calculated in coulombs and time is in seconds, the unit of electric current is coulomb/Sec (C/s) or amperes. The SI unit of current Ampere is denoted by unit symbol A.
Thermodynamic Temperature
The kelvin (abbreviation K), is the SI unit of temperature. One Kelvin is 1/273.16 (3.6609 x 10 -3) of the thermodynamic temperature of the triple point of a pure water that is H 2O.
Supplementary Units
Plane Angle
The name of the unit which is used to calculate the plane angle is radian. Symbol of radian is rad.
Radian describes the plane angle that is subtended by an arc of a circle.
Solid Angle
The name of the unit which is use to describe the solid angle is steradian Symbol of steradian is sr.
A steradian describes the solid angle at the centre of sphere that is subtended on a section of surface.
Derived Units
Few examples of derived units are given below;
Area: Unit name of area is square metre.
Frequency: Unit name is hertz (Hz)
Volume: Unit name is cubic metre
Speed: Unit name is metre per second
Magnetic: Field strength Unit name is ampere pe metre
International System of Units (SI Units) Citations
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Mass and Weight: Definition, Conversion, and Chart
Continue ReadingMass and Weight
Mass is the one of the most significant fundamental quantity of an object in physics and is one the basic property of matter thus is defined as the measure of the amount of matter that is present in a body or substance.
The SI (international system of units) unit of mass is kilograms(kg). The mass of a body does not change it only changes when a huge amount of energy is given or taken from the body for instance in nuclear reaction a huge amount of energy is produced from a certain amount of matter and this lessens the mass of the matter.
The more mass an object has the more force it takes for it to get moving. The symbol of mass is m or M. Various physical quantities like Force, Inertia, and Relative theory of Einstein’s also depend upon mass.
E = mc2
There are various ways of determining the quantity of mass the most used are inertial mass and gravitational mass.
Inertial Mass
It is defined as the mass which is determined by how much an object could resist to acceleration. For instance, if we push two objects with the same amount of force and under the same conditions then object which have lower mass will accelerate faster than the object with the heavy mass.
Gravitational Mass
Gravitational mass is defined as the measurement of how much gravity an object employs on other objects or measurement of how much gravity an object experiences from other objects.
Centre of Mass
Centre of mass of a body can be defined as a point where all the mass of the object is concentrated.
Atomic Mass Unit
The atomic mass unit is used is used to measure the mass of atoms and molecules which are so small, that the kilograms is not so appropriate to use for measurement. One atomic mass unit can be defined as 1/12 the mass of a carbon: 12 atoms.
The value of 1 atomic mass is 1.66 x 10-27..
Mass Conservation
Mass Conservation means that the mass of reactants in the reaction is always equal to the mass of its products.
For Example; An example of law of conservation of mass is coal, the carbon atom in coal becomes carbon dioxide when it is burned or ignited. Thus, carbon atom changes from a solid structure to a gas but the mass of the substance does not change.
Characteristics of Mass
• Mass cannot be zero as everything around us has some mass.
• Mass is measured in grams, kilograms, or milligrams.
• Mass is a scalar quantity which means it only has magnitude.
Weight
Weight is defined as the measure of the force of gravity acting on an object.
S.I unit of weight is Newtons(N). Weight is the measure of the acceleration of gravity
W = mg
In the above expression g is the gravitational field which is equal to 9.8 and/kg and m is denoted as mass.
Characteristics of Weight
• Weight can be measured by via a spring balance.
• Weight can be zero.
• Weight is a vector quantity. Thus, it has both direction and magnitude
Difference Between Mass and Weight
Mass Weight Mass is a scalar quantity which means it only has magnitude Weight is a vector quantity which means it has both magnitude and direction Mass is measured in kilogram, gram, and milligrams Weight is measured in Newtons (N) Mass can never be zero Weight can be zero Mass is not dependent on the gravity and is same everywhere Weight is a physical property that is dependent on gravity and it vary from place to place Mass can be measured with the help of several instruments such as beam balance etc. Weight can be measured with the help of spring balance Relation Between Mass and Weight
The weight of the body can be defined as the force exerted by the earth or any other celestial object on other object.
In case of earth when a body falls towards the earth, the force of gravitation pulls the object with an acceleration denoted as`g`.
According to Newton’s second law, the force of attraction on the body of mass m is F=Mass x Acceleration due to gravity = mg This is force on the object and it is called weight. Thus, W=mg
Mass and Weight Citations
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Metric System: Definition, Conversion, and Chart
Continue ReadingMetric System
The metric system of measurement is the most standard way of measuring distance, height and is also used for calculating many more day-to-day activities.
For instance, Gauri drinks 10 ml of water.
This metric system is used in various fields such as that of science, medicine and so on. Each object is measured according to its length, volume, weight, and time in various manner. This concept of metric system was introduced with the above-mentioned measurements only.
The three main basic units of metric system are;
Metre, a unit use to calculate length of an object.
Kilograms, a unit which is used to measure mass of an object.
Second, a unit of time.
Origin of Metric System
Medication is defined as a process that implements the international system of units called as SI unit. Metric system is followed by nearly all countries except United States, Myanmar, and Liberia.
The United States further introduced its own system of units or system of metric units which is now called as United States customary units.
Difference Between USCS and SI Units
The United States metric units are also called as “imperial units.” The key difference between the SI units and the American metric units is the terms and the form of units used. For instance, In SI unit, the length is measured using the metre whereas In USCS foot is used for measurement.
Metric System Units
Metric unitsGiven below are some of the most used metric units;
Length
This unit length is used for measuring the size of an object or the distance that an object travels from one end to the other end.
There are different units of length which are metre, kilometers, feet etc. The most common tool which is used to measure length is called a ruler.
For Example; The height of this blackboard is about 3 metres.
Smallest unit of measuring length is millimeter and the largest unit is kilometers
1 kilometer = 1000 metre
1 inch =2.5 centimeter
Weight
Weight is the unit that is use to measure the mass of an object. The standard unit that is used for the measurement of mass is kilogram, gram ton etc.
The most common tool which is used to measure the weight of an object is the weighing scale.
For instance; the weight of this bottle is 250 grams.
1 kilogram =1000 gram
Capacity
Capacity is the unit which is used to measure the volume or space occupied by an object or matter. The standard unit used for measurement of capacity is litre. Other units used for measurement of capacity are milliliter etc.
For example; 500 liters of milk
1 litre = 1000 ml
1 cup=250 ml
Time
The standard unit for measurement of time is seconds. Other metric units of time are minutes, hours etc.
1 minute = 60 seconds
1 hour= 60 minutes
1 day = 24 hours
1 week = 7 days
Some few common units based-on metre, kilograms and seconds are;
Speed: Speed is defined as a distance travelled divided by total time taken by an object.
SI unit of speed is metre /second or m/s.
Acceleration: Acceleration is defined as the changes in velocity.
When a runner accelerates from 10 m/s (10 meter per second) to 11 m/s (11 meters per second) in just one second, thus they accelerate by 1 meter per second per second.
SI unit of acceleration is m/s2
Advantages of Metric System
• The metric system allows us to alter the units by changing the decimal to a new place value.
• Metric system is used for easy calculations as metric units generally increase or decrease in a multiple of 10.
For example; there are 1000 grams in 1 kg so one gram is equal to 1/1000 kilogram.
• Nearly all countries use this metric system.
• It has standardized prefix such as gram, kilogram milligram etc.
• Scientists who work in diverse countries need this standardized system that permits them to compare notes and comprehend one another. Without a standard system, they would waste their precious time on converting measurements from one system of measurement to another, and thus accuracy level would also suffer. SI is the most favored system because, among other reasons, it isn’t built on the body parts of society who lived periods ago.
• It’s a well-designed and simple system built on a universal standard that can be confirmed by anyone.
Disadvantages of Metric System
The only drawback in using this metric system is that it is not very well suitable if we work in fractions.
Metric System Citations
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Heterogeneous Mixtures: Examples, Definition, and Types
Continue ReadingHeterogeneous Mixtures Introduction
Anything which has mass and occupies space is called matter. Matter can be divided into;
1. Pure Substances
2. Mixture
Pure substances are made up of only one form of atoms or molecules which cannot be broken down into simpler substances by simple physical method. Element and Compound are examples of pure substances.
Mixtures are made up of two or more substances which are the constituents of mixture. The constituents of mixture can be in any ratio.
Mixtures can be divided into:
1. Homogeneous mixtures
2. Heterogeneous mixtures
Homogeneous mixtures have uniform composition. For instance, sugar in water, water in alcohol etc.
What are Heterogeneous Mixtures?
Heterogeneous mixtures are defined as the mixture where components are mixed non-uniformly. Irrespective of homogeneous mixture where components are in single phase, in heterogeneous mixture components are present in at least two different phases.
Properties of Heterogeneous Mixtures
Heterogeneous mixture shows the following properties:
• It contains two or more ingredients or phases. This phase can be solids, liquids, or gases.
• All the constituents hold their individual properties or chemical identity.
• Constituents displays variable composition.
• The components of mixture can be separated by physical methods.
• There is usually no energy change when mixture is formed.
• There is no change in volume in forming mixture at constant temperature and pressure.
• We cannot transcribe the formula for heterogeneous mixture.
Classification of Heterogeneous Mixture
We can broadly classify heterogeneous mixture into two types:
1. Suspensions
2. Colloids
1. Suspensions
In this type of mixture solute particles do not dissolve, but remain suspended throughout the medium.
Properties of Suspension
1. The particles of a suspension are big and can be seen with a naked eye.
2. As the particles size is pretty big, they throw a beam of light and make the track of light visible, this effect is called The Tyndall effect.
3. As solute particles are quite big, they also settle down when the mixture is left uninterrupted so it can be said that suspension is unstable.
4. The elements of the suspension can be separated by a method of filtration.
Examples of Suspension
1. Kerosene oil and water are the two liquids that do not combine with each other; thus, these types of liquid are called immiscible liquids.
2. Muddy water is also an example of suspension where sand particles are suspended in the liquid water.
3. Common salt in benzene.
4. Wheat flour in water.
5. Concrete is a combination of cement, gravel, sand, and water thus it is an example of suspension.
6. A tossed salad
7. Ice cubes in soda. Before opening it appears to be homogeneous but once heaviness is released, we see the bubbles of gas and liquid.
8. Smoke, an example of suspension in which dust particles, gases, carbon particles are present in different ratios.
Colloids
Colloids are another type of mixtures where the size of particles is between 1nm and 1000nm. Colloids is defined as a mixture where one of the substances is divided into very minute particles which are distributed throughout a second substance. These tiny particles are recognized as colloidal particles.
Properties of Colloids
1. Collides are heterogeneous mixture.
2. When light is conceded through a true solution, the dissolved atoms are too small to deflect the light. But, the dispersed particles of a colloid, being bigger, do deflect light. Thus, The Tyndall effect is the scattering of visible light by colloidal particles.
3. Particles of colloids do not settle at bottom when we left the mixture uninterrupted.
4. Colloids cannot be filtered.
5. The two components of colloidal solution are given below;
i. The dispersed phase: The dispersed particles in a colloid form.
ii.The dispersing mediums: The component in which particles are suspended which are solid, liquid or gas.
Types of Colloids
The dispersion mediums are of three form gas, solid and liquid state. Similarly dispersed phase can be of three types. Based on these two we divide colloid in eight types:
1. Solid sol
2. Solid foam
3. Solid aerosol
4. Sol
5. Gel
6. Emulsion
7. Aerosol
8. Foam
Colloids Dispersing Medium Dispersed Phase Types Clouds, fog, mist, smoke, automobile exhaust Gas Liquid Solid Aerosol Aerosol Shaving cream, face cream, blood, paint, writing ink, mud, milk of magnesia Liquid Gas Liquid Solid Foam Emulsion Sol Rubber, foam, sponge, pumice, jelly, butter, cheese, colored gemstone Solid Gas Liquid Solid Foam Gel Sol Based on nature of the different interactions between the dispersion phase and dispersed phase:
1. Lyophilic If there is an affinity between dispersed medium and phase then these sols are called lyophilic.
For Example: starch, rubber, protein, etc.
2. Lyophobic If there is no affinity between the two phases then these form an unstable colloid.
Examples: sols of metals like gold and silver, sols of metallic hydroxides.
Methods of Separation of Components of Suspensions and Colloids
1. Filtration that is done with the help of filter paper
2. Separating funnel for immiscible liquids such as in oil and water
3. Sedimentation and decantation
4. Centrifugation where mixtures are rotated at a very high speed so that the lighter particles are detached from mixture for example: cream from milk.
Test Used to Identify; Suspensions and Colloids
1. A colloid solution is translucent or turbid in nature and if salt is added to this solution, then this can settle at bottom.
2. If the particles settled at bottom is left uninterrupted for some time then it is a suspension.
Use of a Colloid and a Suspension in Our Daily Life
Colloids are used in pharmaceuticals some insoluble materials become more active when taken in colloidal form.
Suspensions: Barium sulphate when dispersed in water form an opaque suspension which is used in diagnostic X-rays.
Heterogeneous Mixtures Citations
- A density-based threshold model for evaluating the separation of particles in heterogeneous mixtures with curvilinear microfluidic channels. Scientific Reports volume 10, Article number: 18984 (2020).
- The electrical properties of heterogeneous mixtures containing an oriented spheroidal dispersed phase. Colloid and Polymer Science volume 263, pages51–57 (1985).
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Chemical Property Examples
Continue ReadingChemical Property, Physical Property, and Chemical Property Examples
Anything which occupies space and has someone is called matter.
All the substances that we see around us has some properties and these substances can be classified into two properties which are; Physical Properties and Chemical Properties
Physical properties are defined as a characteristic of a substance that is observed without changing the identity of a substance or its molecular formula.
For instance; appearance, odour, texture, boiling and melting points etc.
Chemical property on the other hand is the characteristic of a substance that describes its ability to undergo a specific chemical change.
Chemical Property Examples
Chemical properties that only be established when a substance transforms or changes into a new substance due to the chemical reactions, unlike physical properties which can only be observed by touching or seeing a sample.
Some of chemical property examples are the following;
(a) Flammability
Flammability is defined as the ability of a chemical substance to burn causing fire or combustion.
It is a chemical property because it can only be observed during a chemical change.
Usually, materials categorized are as highly flammable, flammable and non-flammable.
Understanding this chemical property can help us in in handling, storing, and transporting highly flammable materials.
For example; Wood is a flammable substance. Diamond is non-flammable.
(b) Radioactivity
In simple terms radioactivity is defined as the act of emitting radiation from an atom with unstable atomic nucleus spontaneously.
The most common forms of radiation emitted are classified as alpha radiation, beta radiation and gamma radiation.
Some of the most common radioactive elements include Uranium, Radium, Actinium etc.
There is total 38 radioactive elements present in nature.
(c) Chemical Stability
This chemical property is also called as thermodynamics stability of a chemical system.
Chemical stability refers to the stability that takes place when a chemical system is present its lowermost energy state which is a state of chemical equilibrium, or balance, with the environment.
(d) Half life
Half-Life is another chemical property which is defined as the amount of time taken by a substance for one half of its life to decay.
(e) Ability to Oxidize
It is a chemical property that results in the change of oxidation number of a substance either by gaining oxygen or losing hydrogen.
Example of the oxidation encompasses the way an Apple turns into brown colour after it has been cut.
Another example that can be considered for this property is rust, iron and steel will rust over time however they will rust more quickly if they are being combined with the pure oxygen.
(f) Toxicity
Toxicity is the chemical property which is measured by the damage it causes to the organism, plants, and animal.
For instance, chlorine gas, mercury etc.
Lead which is a toxic substance damage various parts of human body which includes bones, kidney, intestine, and reproductive system.
Toxicity is a very vital chemical property because it tells us about the damage a substance can bring to other organisms.
Some common toxic materials include mercury and numerous types of acids.
This also contains the household products, such as those comprising of ammonia.
(g) Heat of Combustion
Heat of combustion is defined as the amount of energy or heat released when a substance is burned with oxygen.
Example for the same include, amount of heat that is produced by burning of several fuels.
A basic example includes the combustion of methane, CH4, with oxygen. Metals also undertake combustion.
(h) Reactivity
Reactivity is defined as the ability of a matter that reacts chemically with other elements. For example, potassium is very reactive metal, on the other hand noble gases such as helium never react with any other substances.
(i) Acidity
Acidity is a chemical property which refers to a substance at ability to react with the acid. Some metals form compounds when they react with diverse acids. Acids react with bases to form water, which further neutralizes the acid.
(j) Enthalpy of Formation
• When a substance is shaped by standard elements, heat is either released or captivated. The heat connected with this is what we call the standard enthalpy of formation.
This is a significant characteristic because it tells us about the stability of the given compound, as well as its reactivity with further compounds.
Chemical Property Examples Citations
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