volume and moles

Question

Cylinder with piston pressing down with constant pressure is filled with 2.00moles of a gas and its volume is 45.0L If 0.700mol of gas leaks out and pressure and temp remain the same, what is final volume of gas in cylinder?

Answer 1

This is an example of Avogadro's Law, which relates volume and number of molecules of a gas when temperature and pressure remain the same. The equation is:

 

V₁/n₁ = V₂/n₂,

 

where V₁ and n₁ are initial volume and amount of gas, and V₂ and n₂ are final volume and amount of gas after some change has been made.

 

For this problem, V₁ = 45 and n₁ = 2. After 0.7 moles leak out, there are 2 - 0.7 = 1.3 moles remaining. So, n₂ = 1.3. Plug those values in and solve for the final volume V₂.