Question

a gas occupies 3 litres at 0°c. What volume will it occupy at -20°cpressure remaining constant?
Solve by Charles' Law
​

Answer 1

Given :

Initial volume = 3 L

Initial temperature = 0° C

Final temperature = -20° C

To Find :

Final volume of the gas.

Solution :

❖ Charles' law : Pressure remaining constant, the volume of a fixed mass of a gas is directly proportional to its absolute temperature.

$\dag\:\underline{\boxed{\bf{\purple{\dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}}}}}$

• V₁ denotes initial volume
• T₁ denotes initial temperature
• V₂ denotes final volume
• T₂ denotes final temperature

First of all we have to convert temperature from Celsius to Kelvin.

• T₁ = 0 ^C = 273 K

• T₂ = -20 °C = -20 + 273 = 253 K

By substituting the given values;

➙ V₁ / T₁ = V₂ / T₂

➙ 3 / 273 = V₂ / 253

➙ V₂ = 3 × 253/273

➙ V₂ = 3 × 0.926

➙ V₂ = 2.778 L

Answer 2

Given :-

• Initial volume = 3 L
• Initial temperature = 0° C
• Final temperature = -20° C

To find :-

• Final volume of the gas .

Solution :-

● Charles' Law : Pressure remaining constant , the volume of a fixed mass of a gas is directly proportional to its absolute temperature.

$\boxed{\sf\pink{V_{1}}}$ = $\boxed{\sf\green{V_{2}}}$

$\boxed{\sf\green{T_{1}}}$ = $\boxed{\sf\pink{T_{2}}}$

• ${\sf{V_{1}}}$ denotes initial volume
• ${\sf{T_{1}}}$ denotes initial temperature
• ${\sf{V_{2}}}$ denotes into volume
• ${\sf{T_{2}}}$ denotes initial temperature

First of all we have to convert temperature from Celsius and Kelvin .

• ${\sf{T_{1}}}$ = O °C = 253 K
• ${\sf{T_{2}}}$ = -20 °C = -20 + 273 = 253 K

By substituting the given values,

:$\implies{\sf{V_{1}~/~T_{1} = V_{2}~/~T_{2}}}$

:$\implies{\sf{3~/~273 = V_{2}~/~253}}$

:$\implies{\sf{V_{2} = 3 × 253/273}}$

:$\implies{\sf{V_{2} = 3 × 0.926}}$

:$\implies\boxed{\bf{V_{2} = 2.778 L}}$ $\large{\bf\green{✓}}$