I got 62.9 mL. Is this correct? I think HCl is the LR.

A piece of solid magnesium is reacted with hydrochloric acid to form hydrogen gas:

Mg (s) + 2HCl (aq) ---> MgCl2 (aq) + H2 (g)

What volume of hydrogen gas (in mL) is collected over water at 25 degrees Celsius by reaction of 0.450 g of Mg (AW= 24.3 g/mol) with 5.00 mL of 1.0 M HCl? The barometer records an atmospheric pressure of 758 torr and the vapor pressure of water at this temperature is 23.35 torr.

2 answers

Close but not there. Since that other problem was close, too, perhaps you are not rounding right. Post your work here and I will check it. MY answer is 63.2 mL.
424.25×10^3 pa