2 Given that CaCO3 s CO2g H2O Ca2 aq 2HC0s aa 321 kl a Wh

2. Given that: CaCO3 (s) CO2(g) + H2O Ca2+ (aq) + 2HC0s (aa) + -321 kl (a) When rainwater, which contains carbon dioxide, runs through underground deposits of limestone (Cac0s), caves form. Explain in terms of equilibrium principles. (b) When hard water (which contains Ca2* ions) is heated in a pan, a deposit forms in the pan. Explain in terms of equilibrium principles. 41 LeChatelier\'s Principle

Solution

a. Rain water contains CO2 runs over the CaCO3 hence the concentration of CaCO3 and CO2 in water increases, hence the rain water become a hard water. in the equilibrium reaction as shown above the concentration of reactants CO2 and CaCO3 increases . Hence according to le chaterlier\'s principles since concentration of reactants increases the equilibrium shifts towards products side hence increasing the rate of forward reaction. So equilibrium shifts towards left /products side.

b. Hard water containing Ca2+ ions in the form of carbonates and bicarbonates. As given in the above reaction when the hard water is heated the equilibrium shifts to right side as the reaction is exothermic.

Exothermic reaction is a reaction where heat is liberated and can be considered as one of the product of the reaction. Hence heating which means increasing the temperature which is on products side makes the equilibrium to shift towards reactants side /right side according to le chaterlier\'s principles. Hence there is an precipitation of Ca2 + ions as CaCO3.