You have a 400-mL container containing 55.0% He and 45.0% Ar by mass at 25°C and 1.5 atm total pressure.You heat the container to 100°C.
-Calculate the total pressure.
A)1.20 atm
B)1.50 atm
C)1.88 atm
D)2.01 atm
E)none of these

Question

Quizplus · Accepted Answer

First, we need to find the partial pressures of He and Ar at 25°C:

PH2 = 1.5 atm x 0.55 = 0.825 atm
PAR = 1.5 atm x 0.45 = 0.675 atm

Using Charles's Law and assuming the volume remains constant, we can find the new pressure at 100°C:

PH2 / T1 = PH2' / T2
0.825 atm / 298 K = PH2' / 373 K
PH2' = 1.032 atm

PAR / T1 = PAR' / T2
0.675 atm / 298 K = PAR' / 373 K
PAR' = 0.845 atm

The total pressure is the sum of the partial pressures:

Ptotal = PH2' + PAR' = 1.032 atm + 0.845 atm = 1.877 atm

Rounding to the nearest hundredth, the answer is 1.88 atm, which is choice C.

You Have a 400-ML Container Containing 55