Question

1. The process of a compound dissolving, as in Reaction 1: Na2B4O5(OH)4 ∙ 8H2O (?) ⇌ 2Na+(??) + B4O5 (OH)4 2−(??) + 8H2O (?) , is called salvation. The enthalpy of salvation can either be positive or negative.

a. If such a reaction is endothermic, what will the sign be of the enthalpy of salvation?

b. Assuming that the above is true, how do you expect the value of K to change when comparing a high and a low temperature?

c. Would the same result be true if the reaction is exothermic instead?

2. Explain how you will determine the concentration of sodium ion in one of your prepared saturated solutions, e.g. outline the calculations you will perform on your measured data. You can make up numbers if that is helpful, or else just use variables.

Answer 1

a) According to convenction since heat is absorbed the sign should be positive.

b) This can be argued using Le Chatelier principle. SInce the reaction is endothermic and proceeds with a decrease in surrounding temperature, the reaction should shift to product side if there is an increase in temperature and hence increases k value .Thus increase in temperature increases k value where as decrease in temperture decreases k value.

c) No the relation will reverse itself.

K value will decrease with increase in temperature and increase with decrease in temperature.