# Using Le Chatelier's Principle determine direction of equilibrium by addition of H+ & increase in temperature

Submitted by rocktown1990 on Mon, 02/27/2012 - 19:15

Use Le Châtelier’s Principle to determine which direction the equilibrium will shift if the following unbalancedreactions are disturbed by:
using a strong acid
an increase in temperature.

a. PO43-(aq) + H+(aq) ⇌ H3PO4(aq)                                               ΔH° -10.9kJ/mol

b. Ca2+(aq) + CO2(g) + H2O(l) ⇌ CaCO3(aq) + H+(aq)              ΔH° = 14.6 kJ/mol
c. NH3(aq) + H+(aq) ⇌ NH4+(aq)                                                     ΔH° = -52.2 kJ/mol
d. CH3Cl(aq) + OH-(aq) ⇌ CH3OH(aq) + Cl-(aq)                          ΔH° = -191.4 kJ/mol

Note:  H+(aq) + OH-(aq) ⇌ H2O(l)

Thanks

a. PO43-(aq) + H+(aq) ⇌ H3PO4(aq)                                               ΔH° -10.9kJ/mol
Adding H+ favours forward reaction ---->
Strong acid adds more H+ ions
Increase in temperature favours reverse reaction for any exothermic reaction (as system will go in endothermic direction to lower temperature.

b. Ca2+(aq) + CO2(g) + H2O(l) ⇌ CaCO3(aq) + H+(aq)              ΔH° = 14.6 kJ/mol
Adding H+ favours reverse reaction <----
Strong acid will favour reverse reaction by reacting with more CaCO3
Increase in temperature favours forward reaction for any endothermic reaction (as system will go in endothermic direction to lower temperature.

c. NH3(aq) + H+(aq) ⇌ NH4+(aq)                                                     ΔH° = -52.2 kJ/mol
Adding H+ favours forward reaction ---->
Strong acid favours forward reaction
Increase in temperature favours reverse reaction for any exothermic reaction (as system will go in endothermic direction to lower temperature.

d. CH3Cl(aq) + OH-(aq) ⇌ CH3OH(aq) + Cl-(aq)                          ΔH° = -191.4 kJ/mol
Adding H+ favours reverse reaction <---- as OH- ions are removed as water, slowing down forward reaction but allowing reverse reaction.
Strong acid as for adding H+
Increase in temperature favours reverse reaction for any exothermic reaction (as system will go in endothermic direction to lower temperature.

Exothermic reactions are favoured by low temperatures, Endothermic reactions are favoured by high temperatures