Question

QUESTIONS 1. What do you notice about the solubility of calcium hydroxide as the temperature increases? Is this typical for most solids? (1 mark)

Answer 1

1. Solubility of Ca(OH)₂ (Calcium Hydroxide) as the temperature increases

When the temperature increases the Solubility of Calcium Hydroxide decreases. In Short, Solubility can be defined as capability of the Solute( the Solid Substance), to get dissolved in a Solvent(liquid). It is noticed that the Solubility of Calcium Hydroxide will decrease when we increase the temperature. There are possiblities that the temperature can alter the Solubility. This concept can be explained using Le Chatelier's Principle for understanding much more better.

What is Le Chatelier Principle?

A System which is in equilibrium state, will sense a Pressure. The system act in response by altering the proportion of the reactants and the products, to get alleviated from this pressure. The switch may be in the direction of left or right.

For Calcium Hydroxide dissolution process is exothermic($\Delta$_sol H < 0). The reaction is

Ca(OH)_2(s) + H₂O _(l)   $\leftrightharpoons$ Ca²⁺_(aq) +2 OH-_(aq) +  $\Delta$

By dissolving the solid Calcium Hydroxide crystals in the aqueous solution, the solubility decreases when the temperature increases. Among the Crystallisation and dissolution with solvation an equilibrium is observed. When the temperature is increased, the equilibrium will move in the reverse direction for enchancing crystallisation, instead in the forward direction. As the Solvation Process is also exothermic, when the temperature gets increased,the equilibrium moves in reverse direction. According to Lechatelier Principle, the consumption of heat by the system is responsible for the equilibrium moving in reverse direction. As a result, the pressure experienced by the system in equilibrium gets reduced and the solubility gets decreased and there is a larger yield of Ca(OH)₂