Question

? When a sample of potassium nitrate is heated, oxygen gas is produced. This gas, collected in a 750 milliliter flask, has a pressure of 2.8 atmosphere and the temperature is recorded to be 53.6°C. How many moles of oxygen gas are produced in this reaction? (R = 0.08205 L atm/K mol)

0.477 mol

0.078 mol

77.72 mol

477.5 mol

Answer 1

P = 2.8 atm, V = 750 mL = 750/1000 L = 0.75L,  n = ?, T = 53.6 + 273 = 326.6 K, R = 0.08205 Latm/Kmol
 
PV = nRT

n = PV/RT

n =  (2.8*0.75) / (0.08205*326.6)

n ≈ 0.078 mol

Answer 2

0.078 mol is the answer