Aluminium compounds. Copper
Answers are for parents and teachers.
1
Write the reaction of Al₂O₃ with KOH in aqueous solution.
Al₂O₃ + 2KOH + 3H₂O → 2K[Al(OH)₄]
2
How many grams of aluminium are in 474 g of alum KAl(SO₄)₂·12H₂O? (M = 474, A(Al) = 27)
27
3
How many grams of Cu are obtained by reducing 80 g of CuO with hydrogen? (M(CuO) = 80, A(Cu) = 64)
64
4
Write the equations for the changes Cu → CuO → CuSO₄ → Cu(OH)₂.
2Cu + O₂ → 2CuO; CuO + H₂SO₄ → CuSO₄ + H₂O; CuSO₄ + 2NaOH → Cu(OH)₂↓ + Na₂SO₄.
5
Name two uses each of copper and its alloys.
Copper: electric wires, vitriol (pesticide); bronze and brass: statues, machine parts, instruments.