Question

Write the net ionic equation and describe the reactions occurring.

1) 2 KAl(OH)_4(aq) + H₂SO_4(aq) ----> 2 Al(OH)_3(s) + K₂SO_4(aq) + 2 H₂O_(l)

2) 2 Al(OH)_3(s) + [6 H⁺ + 3 SO^2-_4(aq) ----> [2 Al³⁺ + 3SO^2-₄]_(aq) + 6H₂O_(l)

The following is a bank for the types of reactions that can be occurring. Two or more can be present in one equation.

Metathesis Reactions

Redox Reactions

Single Displacement Reactions

Double Displacement Reactions

Combination Reactions

Decomposition Reactions

Answer 1

Given are the steps involved in the preparation of hydrated potash alum.

The first reaction (1) is an acid-base reaction and here the Bronsted-Lowry acid H₂SO₄ neutralizes [Al(OH)₄]^- to yield [Al(OH)₃].

So the net ionic equation is

[Al(OH)₄]^- (aq) + H⁺ (aq) [Al(OH)₃] (aq) + H₂O(l)

The second reaction (2) which is written has some errors in it, the species given as 3 SO₂^4- (aq) is wrong this is actually 3 SO₄^2- (aq) which is the sulfate ion. So the second reaction can be written as

2 Al(OH)₃ (s) + [6 H⁺ + 3 SO₄^2- (aq)] [2 Al³⁺ + 3 SO₄^2- (aq)] + 6 H₂O (l)

or

2 Al(OH)₃ (s) + 3 H₂SO₄ (aq)Al₂(SO₄)₃ (aq) + 6 H₂O (l), this is a double replacement reaction

The net ionic equation is

2 Al(OH)₃ (s) + H⁺ (aq) Al³⁺ (aq) + 3 H₂O (l)