Magnesium metal reacts with hydrochloric acid to form magnesium chloride and hydrogen gas.

Question

Magnesium metal reacts with hydrochloric acid to form magnesium chloride and hydrogen gas. Suppose we react an excess of magnesium metal with 19.0 mL of a 3.00 M solution of hydrochloric acid and collect all of the hydrogen in a balloon at 25oC and 1.00 atm. What is the expected volume of the balloon?

a. 0.310 L

b. 0.0585 L

c. 0.697 L

d. 58.5 L

e. 1.39 L

Answer 1

2HCl + Mg → MgCl₂ + H₂

0.019 L_sln*(3 mol HCl/Lsln)= 0.057 mol HCl

By stoich relation

0.057 mol HCl * (1 mol H₂/2 mol HCl)=0.0285 mol H₂

By applying ideal gas equation

V_H2=nRT/P=(0.0285mol*0.0821atm L mol^-1 K^-1 *523K)/1atm=1.22 L