Question

A 0.069 gram sample of a metal reacted with HCl and produced 45.31 mL of H
2
gas at
25¡ÆC and 1 atm pressure. The metal is known to react with HCl according to the following
reaction,
2 M + 6 HCl
> 2 MCl
3
+ 3 H
2
What is the molar mass of the metal? Which metal is it?

Answer 1

You would do better to write your equations in a left to right line (horizontal) rather than a vertical line.

2M + 6HCl>>> 2MCl3 + 3H2
Use PV = nRT and solve for n H2 gas.
Using the coefficients in the balanced equation, convert mols H2 to mols M. Then mols = grams/molar mass. You know grams and mols, solve for molar mass.
Then identify the element from the periodic table.
NOTE: This metal actually forms MCl2 with HCl and not MCl3.