ΓΌ Charle’s
Law (Volume – Temperature Relationship): the volume of fixed mass of a gas is directly
proportional to absolute temperature. Mathematically, it is written as
V
Ξ± T |
Or, V
= k2 x T
Or, V/T
= k2, a constant
Consider a fixed amount of gas at constant pressure P.
Let V1 be its volume at a temperature T1 and V2
be its volume at a temperature T2.
Then according to Charle’s law:
V1/T1 = V2/T2 |
Since
the graph is obtained at constant pressure, it is called Isobar.
If
we extend the graph to temperature axis (X-axis), the graph will meet at
-273.150C. At this temperature, the volume of the gas becomes zero. This
lowest hypothetical or imaginary temperature at which gases are supposed to
occupy zero volume is called Absolute
zero of temperature and the scale of temperature based
on absolute zero is called Absolute scale of temperature. All
gases become solid or liquid before reaching this temperature.
Note: 1. All gases obey Charle’s law at very low pressures and high temperatures.
2. Boyle's and Charles’ law are examples of a limiting law, a law i.e. strictly true only in certain limit in this case p→0.
ΓΌ Gay
Lussac’s law: It
states that at constant volume, pressure of a fixed amount of a gas is directly
proportional to the temperature.
Mathematically,
p Ξ± T (V, n constant) |
P/T
=
a constant
If we plot a graph between pressure and temperature of a fixed mass of gas at constant volume, the graph obtained is as follows:
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