A small quantity of solid ammonium chloride was heated gently in a test tube; the...
A small quantity of solid ammonium chloride was heated gently in a test tube; the solid gradually disappeared to produce a mixture of two gases. Later a white cloudy deposit was observed on the cooler part of the test tube. The ammonium chloride is said to have undergone _______
- A) distillation
- B) sublimation
- C) precipitation
- D) evaporation
Correct Answer: B) sublimation
Explanation
When solid ammonium chloride is heated gently in a test tube, it disappears gradually to produce a mixture of two gases. Later, a white cloudy deposit is observed on the cooler part of the test tube. The process that the ammonium chloride undergoes in this case is what the question is asking about.The options provided are distillation, sublimation, precipitation, and evaporation. Distillation involves separating a mixture of liquids based on differences in boiling points. Precipitation is the formation of a solid from a solution. Evaporation is the conversion of a liquid to a gas.
The correct option in this case is sublimation. Sublimation is the process of conversion of a solid directly to a gas without passing through a liquid phase. This is what occurs when ammonium chloride is heated gently, and it disappears to produce a mixture of two gases. The white cloudy deposit observed on the cooler part of the test tube is a result of the gas condensing back into a solid on the cool surface.
In summary, the process that occurs when solid ammonium chloride is heated gently in a test tube, leading to the production of two gases and a white cloudy deposit on the cooler part of the tube is sublimation.