Why does the temperature rise when sodium hydroxide is added to water?

Answer 1

Sodium hydroxide (NaOH) is completely ionic, containing sodium ions and hydroxide ions. The hydroxide ion makes sodium hydroxide a strong base which reacts with acids to form water and the corresponding salts, e.g., with hydrochloric acid, sodium chloride is formed:

NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

In general such neutralization reactions are represented by one simple net ionic equation:

OH−(aq) + H+(aq) → H2O

This type of reaction releases heat when a strong acid is used.

Answer 2

it probably give off heat... this is the exothermic reaction