WAEC - Chemistry (2000 - No. 18)
Which of the following compounds dissolves in water to give an alkaline solution?
Ammonium chloride
Sodium chloride
Sulphur (IV) oxide
Potassium oxide
Explicaţie
When potassium oxide (K2O) reacts with water (H2O), it produces potassium hydroxide (KOH):
- Chemical equation:
K2O + H2O → 2KOH - The reaction produces a hydroxide compound because the potassium ion balances the hydroxide ion and the solution is alkaline because of the high level of hydroxide ions, which gives it a high pH. Therefore, the correct answer is option D