Question

QUESTION 6
How many grams of H 2 will be produced if 26.9 mL of 0.254 M HCl solution are combined with excess Mg metal? The reaction is 2 HCl + Mg ---> H2
+ MgCl2

Answer 1

Answer:

0.00610 g H₂

Explanation:

The equation for the reaction;

2HCl(aq) + Mg(s) → H₂(g)+ MgCl₂(aq)

Given;

Volume of HCl = 26.9 mL or 0.0269 L

Molarity of HCl = 0.254 M

We need to calculate the mass of H₂ produced

Step 1: Calculate the number of Moles of HCl

Moles = Molarity × Volume

Moles of HCl = 0.254 M × 0.0269 L

                      = 0.00683 moles

Step 2: Moles of Hydrogen gas produced

from the Equation 2 moles of HCl reacts to produce 1 mole of Hydrogen gas

Therefore; Mole ratio of HCl to H₂ is 2 : 1

Moles of H₂ = 0.00683 moles ÷ 2

                   = 0.003415 moles

Step 3: Mass of Hydrogen gas

Mass = Number of moles × molar mass

Molar mass of H₂ = 2.02 g/mol

Therefore;

Mass of H₂ = 0.003415 moles × 2.02 g/mol

                 = 0.00610 g

Therefore, mass of hydrogen gas produced is 0.00610 g