A specified quantity of an unknown gas has the volume of 14.1 mL at 22°C and 659 torr. Calculate the volume at STP.
A) 0.912 mL
B) 13.2 mL
C) 11.3 mL
D) 15.0 mL
E) none of these

Question

Quizplus · Accepted Answer

First, we need to use the Ideal Gas Law to find the number of moles of gas present:

PV = nRT

n = PV/RT

n = (659 torr)(0.0141 L)/(0.08206 L·atm/mol·K)(295.15 K)

n = 0.000686 mol

Next, we can use the molar volume of a gas at STP (standard temperature and pressure) to find the volume of the gas at STP:

V = nRT/P

V = (0.000686 mol)(0.08206 L·atm/mol·K)(273.15 K)/(1 atm)

V = 0.0113 L = 11.3 mL

Therefore, the best choice is C, 11.3 mL.

A Specified Quantity of an Unknown Gas Has the Volume