consider the following reaction equation: 2Al(OH) 3 + 3H 2 SO 4 →Al 2 (SO4) 3 (aq)+6H 2 O. How many moles of…

Analyze the question: We need the moles of H₂SO₄ required to make 0.5 mol of Al₂(SO₄)₃, using the mole ratio from the balanced equation.

Concept: The coefficients in a balanced equation give the mole ratio of reactants and products.

2Al(OH)₃ + 3H₂SO₄ → Al₂(SO₄)₃ + 6H₂O

Solution:

From the equation:

• 3 mol H₂SO₄ produces 1 mol Al₂(SO₄)₃

So the ratio is H₂SO₄ : Al₂(SO₄)₃ = 3 : 1.

For 0.5 mol Al₂(SO₄)₃:

moles of H₂SO₄ = 3 × 0.5 = 1.5 mol

Tip: In stoichiometry questions, write down the ratio first (here 3 : 1), then multiply by the amount given. Always check that the equation is balanced before using the coefficients. Here, Al: 2 = 2, S: 3 = 3, and O and H also balance.