When pelletes of Sodium Hydroxide added to a test tube containing water, the test tube feels warm why?
Answers
Answer:
The following (rate depends on ambient conditions- temperature and especially relative humidity):
The pellet begins to absorb humidity from the atmosphere.
As it does so, it will gradually deliquesce (soften and dissolve into the absorbed water). If temperatures are below freezing, it will still absorb humidity to a certain point but will not turn liquid. If temperatures are high but very dry (e.g. desert conditions, the same thing will happen. High humidity is the key requirement for it to actually become liquid.
During this process, it is continually absorbing carbon dioxide from the atmosphere. This reacts with the water to form carbonic acid which immediately reacts with the hydroxide and is converted to sodium carbonate. The process is much slower in the solid phase than the liquid phase. Overall this is a very slow process, such that bulk tanks of 50% sodium hydroxide are normally vented to the atmosphere without any worry of excessive carbonate formation.
Answer:
1. The pellet begins to absorb humidity from the atmosphere.
2. As it does so, it will gradually deliquesce (soften and dissolve into the absorbed water). If temperatures are below freezing, it will still absorb humidity to a certain point but will not turn liquid. If temperatures are high but very dry (e.g. desert conditions, the same thing will happen. High humidity is the key requirement for it to actually become liquid.
3. During this process, it is continually absorbing carbon dioxide from the atmosphere. This reacts with the water to form carbonic acid which immediately reacts with the hydroxide and is converted to sodium carbonate. The process is much slower in the solid phase than the liquid phase. Overall this is a very slow process, such that bulk tanks of 50% sodium hydroxide are normally vented to the atmosphere without any worry of excessive carbonate formation.
Explanation: