Question

A sample of helium occupies a volume of 3.8 L at -45°C. What volume will it occupy at 45°C?

can you work it out please?! thanks

Answer 1

5.3 L.

Step-by-step explanation

By Charles's Law,

• the volume of an ideal gas is proportional to its absolute temperature when its pressure is held constant.

In other words,

`(V_2)/(V_1) = (T_2)/(T_1)`,

where

• 
  `V` is the volume of the gas, and
• 
  `T` is the absolute temperature of the gas in degrees Kelvins.

As a noble gas, helium is quite "ideal" with rather weak attractions between its particles unless in direct contact.

Convert the temperatures:

• 
  `T_1 = -45 \textdegree\text{C} = (-45 + {\bf 273.15} ) \; {\textbf{K}} = 228.15 \; \text{K}`;
• 
  `T_2 = 45 \textdegree\text{C} = (45 + {\bf 273.15} ) \; {\textbf{K}} = 318.15 \; \text{K}`.

Apply Charles's Law,

`V_2 = V_1 \cdot (T_2)/(T_1) = 3.8 * (228.15)/(318.15) = 5.3 \; \text{L}`.