The correct balanced equation for the reaction between aluminium metal and hot concentrated tetraoxosulphate(VI)acid is ?

Analyze the question: Aluminium reacts with hot concentrated H2SO4. Concentrated sulphuric acid acts as an oxidising agent, so it is reduced to SO2 rather than releasing H2. The task is to find the balanced equation.

Concept: Al is oxidised from 0 to +3, and S is reduced from +6 to +4 in SO2. Electrons must balance, and so must the atoms.

Step by step:

1. Electrons lost: 2 Al → 2Al³⁺ + 6e⁻
2. Electrons gained: each S(+6) → S(+4) gains 2e⁻, so 3 SO2 gain 6e⁻. This matches, which gives 3 SO2.
3. Sulphate in the salt: Al2(SO4)3 contains 3 SO4.
4. Total sulphur needed on the right: 3 (in the salt) + 3 (in SO2) = 6, so we need 6 H2SO4.
5. Hydrogen: 6 H2SO4 gives 12 H, which forms 6 H2O.
6. Check oxygen: • Left: 6 × 4 = 24 O • Right: Al2(SO4)3 has 12 O, 6 H2O has 6 O, 3 SO2 has 6 O, so the total is 24 O ✔

Balanced equation:

2Al + 6H2SO4 → Al2(SO4)3 + 6H2O + 3SO2

Checking the other options:

• B has only 3 H2SO4, so sulphur (3 vs 6) and hydrogen (6 vs 12) don't balance.
• C has 4 H2SO4 with 8 H2O, so sulphur (4 vs 6) doesn't balance.
• D has 5 H2SO4, so sulphur (5 vs 6) doesn't balance.

Tip: For metal + hot concentrated H2SO4, the products are always salt + water + SO2. Balance in this order: electrons → sulphur → hydrogen → check oxygen.