* Endothermic reactions absorb heat from the surroundings. This means the temperature of the solution will decrease as the sodium carbonate dissolves.

* Sodium carbonate dissolving in water is a process that requires energy to break the bonds holding the sodium carbonate crystal together. This energy is absorbed from the surroundings, leading to a cooling effect.

You can observe this endothermic effect by feeling the container in which you are dissolving sodium carbonate – it will feel colder than the surrounding air.