QQuestion
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 R:
(a) will react with Magnesium to liberate hydrogen gas?
(b) will liberate ammonia gas when it reacts with ammonium chloride?
(c) will contain molecules as well as ions?
✓Answer
(a) 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.
(b) Ammonium chloride reacts with strong bases to release ammonia gas. A solution with a high pH (basic nature) is required for this reaction to take place. Solution P, with a pH of 13, is strongly basic and will liberate ammonia gas when it reacts with ammonium chloride.
(c) 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.
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