Question

1. For the following balance: 2 HF (g) H2 (g) + F2 (g) 73Kcal Indicate what will happen with each of the following changes: a) Decrease in HF concentratiorn b) Increase in temperature c) Decrease in pressure d) Increase in H2 concentration ej Increase in the concentration of F2 2. At 130 oc the sodium bicarbonate, NaHCO3, decomposes partially according to the following equilibrium: 2 NaHCO3 (s) sNa2CO3 (s) + CO2 (g)+ H20 (g) Ko= 6.25. 100 g of NaHCO3 (s) are introduced into a closed container of 2 L capacity, in which the vacuum has previously been made, and heated to 130 oC. Calculate: a) The value of KC. bj The amount, in grams, of NaHCO3 that will remain without decomposing.

Answer 1

2HFg rightleftharpoons H_2(g) + F_2(g): Delta H = -73 kcal a) If [HF] is decreased the equilibrium moves to left. b) If Temperature increases, the equilibrium shift to left. c) If pressure decreases, no change because same no. of moles of reactants and products. d) [H_2] increases, equilibrium shift to left e) [F_2] increases, the equilibrium shift to left. All the above can be explained according to Le Chatlier's principle.