Answer to Question #92045 in Chemistry for trey

Question

A sample of gas at 25°C has a volume of 8 L and exerts a pressure of 690 mm Hg. How many moles of gas are in the sample?

Answer 1

Task:

Convert:

T = 25^oC = (25+273.15) = 298.5 K;

P = 690 mmHg = (690 mmHg * 1 atm / 760 mmHg) = 0.907895 atm;

V = 8 L;

R = 0,0821 L*atm / mol*K;

The Ideal Gas Law is expressed: PV = nRT;

Then,

n = PV / RT = (0.907895 atm * 8 L) / (0,0821 L*atm / mol*K * 298.5 K) = 0.2967 mol

n = 0.2967 moles

Answer: 0.2967 moles of gas are in the sample.