How much of magnesium is required to react with 250cm³ of 0.5 M HCl? [Mg = 24]

Explanation

When magnesium reacts with hydrochloric acid, the balanced equation is:

Mg + 2HCl → MgCl₂ + H₂

This equation tells us that 1 mole of magnesium reacts with 2 moles of HCl.

Step 1: Find the number of moles of HCl.
Moles = Concentration × Volume (in dm³)
Volume = 250 cm³ = 250 ÷ 1000 = 0.25 dm³
Moles of HCl = 0.5 × 0.25 = 0.125 mol

Step 2: Find the moles of magnesium needed.
From the equation, 2 moles of HCl react with 1 mole of Mg.
So moles of Mg = 0.125 ÷ 2 = 0.0625 mol

Step 3: Find the mass of magnesium.
Mass = Moles × Molar mass
Mass = 0.0625 × 24 = 1.5g

Therefore, 1.5g of magnesium is required to react with 250 cm³ of 0.5 M HCl.