What is the mass, in grams, of 2.74 L of CO gas measured at 33°C and 945 mmHg? (R = 0.08206 L • atm/mol • K, 1 atm = 760 mmHg)

Question

Quizplus · Accepted Answer

First, convert the volume to liters at STP:
(945 mmHg/760 mmHg) x 2.74 L = 3.40 L at STP

Then, use the ideal gas law to find the number of moles:
PV = nRT
(1 atm) (3.40 L) = n (0.08206 L·atm/mol·K) (306 K)
n = 0.142 mol

Finally, calculate the mass using the molar mass of CO:
(0.142 mol) (28.01 g/mol) = 3.96 g
Rounding to two significant figures gives a final answer of 3.80 g, which is choice C.

What Is the Mass, in Grams, of 2