Question

1. The old unit of energy was the "Calorie". The new S.I. unit of energy is the "Joule". Define what is meant by "joule." Convert 6.66 calories to joules.

2. Will a weak acid/strong base neutralization have the same molar heat of neutralization as the strong acid/strong base neutralization? Explain.

3. if you have used 100 mL of water and 15.0 g of NH4Cl in the experiment to determine change of heat solution, would you expect to get a larger, smaller, or identical temperature change? why?

4. why is the dissolving of ammonium chloride endothermic? Would you get similar results for dissolving all salts? Explain the answer using another salt as an example.

Answer 1

(1)

Joule is equal to the energy transferred to an object when a force of 1 Newton acts on that object in the direction of its motion through a distance of 1 metre.

1 cal = 4.184 J

then, 66.6 cal = 66.6 * 4.184 = 278.65 J

(2) No. It has less heat of neutralisation than that of strong acid and strong base.

Becuase certain amount of energy is consumed to ionize the weak acid as it undergoes artial dissocition.

HA (aq.) H⁺ (aq.) + A^- (aq.)

Partial ionisation of weak acid