O Levels Chemistry (5070)•5070/11/M/J/20
Explanation
Ammonia liberation from ammonium salts via base reaction
Steps:
- Ammonium nitrate dissociates in water to NH4+ and NO3- ions.
- Ammonia gas (NH3) is liberated when NH4+ reacts with a strong base like hydroxide on warming.
- Potassium hydroxide (KOH) provides OH- ions for this reaction.
- The equation is NH4NO3 + KOH → KNO3 + NH3↑ + H2O.
Why B is correct:
- KOH, a strong base, reacts with NH4+ to produce ammonia gas via acid-base neutralization, forming water and the soluble nitrate salt.
Why the others are wrong:
- A. Calcium nitrate is a neutral salt with no basic properties to react with NH4+.
- C. Sodium chloride is a neutral salt that does not affect the ammonium ion.
- D. Sulfuric acid is an acid that would form ammonium sulfate, not liberate NH3.
Final answer: B
Topic: The characteristic properties of acids and bases
Practice more O Levels Chemistry (5070) questions on mMCQ.me