Question

Help please:
A 0.199-g sample of unknown metal (X) reacts with hydrochloric acid to produce 88.5 mL of "wet" gas at 20 °C and 754 mm Hg. What is the unknown metal (X)? (The vapor pressure of water at 20 °C is 18 mm Hg.)
X(s) + 2 HCl(aq) → XCl2(aq) + H2(g)
(Would Mg be correct?)

Answer 1

I don't think so.
Pdry gas = 754mm - 18 mm = 736 mm and
P gas in atm is 736/760 = ?
Then PV = nRT or
n = PV/RT = 736*0.0885/(760*0.08206*293) = ?
Then mols = g/atomic mass or
atomic mass = g/mols. Atomic mass Mg is about 24 and I obtained more than twice that.

Answer 2

Would it be possible for someone to explain how you figure out which element is the answer? I'm clueless on this problem myself.