Question

For the reaction CaC2O4(s) ++ Ca2(aq)+ C204(aq), K = 2.3 x 10. (next two questions) 14. What is the equilibrium expression for this reaction? 15. If someone mixed 1.00 mole of calcium ions with 0.500 mole of oxalate ions (1.00mol Ca2 and 0.500mol C2O42) in a 5.00L vessel, what would be the predominate species present at equilibrium? Which reactants and/or products would be present in appreciable amounts? 16. What general temperature and pressure conditions would cause a maximum yield of water? 2H2(g) + O2(g) 2H2O (g) AH <0.

Answer 1

14) K = [Ca^{​​​​​+2}][C_{​​​​​2}​O_​4 ^-2 ]

Concentration of a solid to be considered as unity.

15) As per the given equilibrium reaction, for every one mole of calcium ion, one mole of oxalate ions are present, hence 0.5 mole of oxalate ions react with 0.5 mole of calcium ions, and finally 0.5 mole of un reacted calcium ions are predominantly present at equilibrium.

Characteristics of equilibrium constant:-

1) If the value of equilibrium constant is >10³ , then the reaction is favourable for forward direction.

2) If the value of equilibrium constant is < 10^-3 , then the reaction is favourable for backward direction.

The given value of equilibrium constant shows that, the reaction is favourable for backward direction and hence CaCO_​​​3​​ predominantly present at equilibrium.

16)

The given reaction is an exothermic reaction, hence the reaction is favourable at low temperature.

The given reaction is having more number of moles of gaseous reactants than the number of moles of gaseous products.

Hence the reaction is favourable at high pressure to get more water.

(According to Le-Chatelier principle)