1. How many moles of gas would be found in a rigid 5.0 L cylinder at 12.0 atm of pressure at 15 C 2. What is the volume of 7.5 mol argon?

1.
PV = nRT
n = PV/(RT)

Number of moles of the gas, n
= PV/(RT)
= (12 atm) × (5.0 L) / {[0.0821 atm L / (mol K)] × [(273 + 15) K]}
= 2.5 mol

...... The answer is : C. 2.5 mol


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2.
1 mol of gas occupies 22.4 L of volume at STP.

Volume of argon at STP
= (7.5 mol) × (22.4 L/mol)
= 168 L

...... The answer is : B. 168 L