Question

Mohan has three solutions P, Q and R having a pH of 13, 5 and 2 respectively. Which of the above solutions P, Q or

1. will react with magnesium to liberate hydrogen gas?
2. will liberate ammonia gas when it reacts with ammonium chloride?
3. will contain molecules as well as ions?

Answer 1

1. Magnesium reacts with acids to liberate hydrogen gas. Therefore, Solutions Q (pH 5) and R (pH 2) will react with magnesium to liberate hydrogen gas.
2. Ammonium chloride reacts with strong bases to release ammonia gas. This reaction requires a high-pH (basic) solution. Solution P, with a pH of 13, is strongly basic and will liberate ammonia gas when it reacts with ammonium chloride.
3. Solution Q (pH 5) will contain both molecules (of the weak acid) and ions (hydrogen ions), as it is a moderately acidic solution where some acid will be in molecular form and some in ionic form.