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Charles' Law

The volume of an enclosed sample of gas is directly proportional to its absolute temperature provided the pressure is kept constant.

Interesting fact

Charles's Law is also known as Gay-Lussac's Law. Charles did not publish his work. Gay-Lussac later rediscovered this law and referenced Charles's work, but said that it was only by great luck that he knew of it and that his experiment was different.

Demonstration : charles's law


To demonstrate Charles's Law using simple materials.


glass bottle (e.g. empty glass coke bottle), balloon, bunsen burner, retort stand


  1. Place the balloon over the opening of the empty bottle.
  2. Place the bottle on the retort stand over the bunsen burner and allow it to heat up. Observe what happens to the balloon. WARNING: Be careful when handling the heated bottle. You may need to wear gloves for protection.


You should see that the balloon starts to expand. As the air inside the bottle is heated, the pressure also increases, causing the volume to increase. Since the volume of the glass bottle can't increase, the air moves into the balloon, causing it to expand.


The temperature and volume of the gas are directly related to each other. As one increases, so does the other.

Mathematically, the relationship between temperature and pressure can be represented as follows:



V = k T

If the equation is rearranged, then...

V T = k

and, following the same logic that was used for Boyle's law:

V 1 T 1 = V 2 T 2

The equation relating volume and temperature produces a straight line graph (refer back to the notes on proportionality if this is unclear). This relationship is shown in [link] .

The volume of a gas is directly proportional to its temperature, provided the pressure of the gas is constant.

However, if this graph is plotted on a celsius temperature scale, the zero point of temperature doesn't correspond to the zero point of volume. When the volume is zero, the temperature is actually -273.15 C ( [link] ).

The relationship between volume and temperature, shown on a Celsius temperature scale.

A new temperature scale, the Kelvin scale must be used instead. Since zero on the Celsius scale corresponds with a Kelvin temperature of -273.15 C, it can be said that:

Kelvin temperature (T) = Celsius temperature (t) + 273.15

At school level, you can simplify this slightly and convert between the two temperature scales as follows:

T = t + 273


t = T - 273

Can you explain Charles' law in terms of the kinetic theory of gases? When the temperature of a gas increases, so does the average speed of its molecules. The molecules collide with the walls of the container more often and with greater impact. These collisions will push back the walls, so that the gas occupies a greater volume than it did at the start. We saw this in the first demonstration. Because the glass bottle couldn't expand, the gas pushed out the balloon instead.

Charles's law

The table below gives the temperature (in C) of a number of gases under different volumes at a constant pressure.

Questions & Answers

explain why HCL is a Bronstead lowry acid . use an equation of HCL in water to explain
Mihlali Reply
what is electron. ( you should not allowed to tell it properties in it defination.)
vigyan Reply
a charged particle.
investigative question
Obakeng Reply
how do you create a bomb
Nasty Reply
how can I create a bomb
how can I create a bomb
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how can I create a bomb
how can I create a bomb
how can I create a bomb
how can I create a bomb
how can I create a bomb
how can I create a bomb
if you want to create bomb use this chemical substance oxidised, sulphuric acid,tobacco,gas and flammable substance , mix all this substance together and put in strong mental bottle like gas bottle put in . you must close the bottle very parked and carry that bottle carefully and shake in 5 minutes
after shake put this bottle were the temperature is 100 degrees Celsius after moment that bottle will be high explosion like bomb
what is mass
asmerom Reply
is object amount matter contain by object
what is hypothesis
hypothesis is a tentative explanation that does not have facts and it can be proven to be wrong or right
wath is physical science
Siphelo Reply
what is physics
Dineo Reply
the branch of science concerned with the nature and properties of matter and energy
use a vector scale diagram and represent the two displacements(5m east and 7m west)
itumeleng Reply
what os covalent?
Shellah Reply
can i ask something?
Uapfa Reply
how to calculate enthalpy on a reaction?
how do you learn this chapter festet
Lisakhanya Reply
it's not all about learning it fast but understanding the basics, the concepts. formulas .. if you juss understand the basics you know the chapter .understand it
you are right precious
can i ask smething.?
electric field around a point
Sameer Reply
The force per positive unit charge
what is Kevlar made of ?
Crazy Reply
How do I determine the number of valence electrons for an atom
Kamohelo Reply
look at its group number on periodic table. group 2 elements will have 2 valence electrons and so on for all the groups. (correct me if I'm wrong but this is how I remeber it )
how to find a point between to charges that is zero?
Thyrin Reply

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Source:  OpenStax, Siyavula textbooks: grade 11 physical science. OpenStax CNX. Jul 29, 2011 Download for free at http://cnx.org/content/col11241/1.2
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