Calorimetry

Question 1

Calorimetry is the measurement

Answer 1

Calorimetry is the measurement enthalpy changes in chemical reactions

Question 2

simple calorimeter can be made from

Answer 2

polystyrene drinking cup, a vacuum flask or metal can

Question 3

specific heat capacity (c) of the liquid
is what

Answer 3

The energy needed to increase the temperature of 1 g of a substance by 1 oC is called the specific heat capacity (c) of the liquid

Question 4

The specific heat capacity of water is

Answer 4

4.18 J g-1 oC-1

Question 5

The energy transferred as heat can be calculated by:
and units

Answer 5

q = m x c x ΔT)

q= heat transferred in joules

m= mass in grams

c= specific heat capacity jg(power -1)degrees(power -1)

ΔT)= change in temperature (degrees

Question 6

When new bonds are formed the amount of energy released is equal to the amount of

Answer 6

energy absorbed when the same bonds are broken.

For example:

O2 (g) → 2O (g) E (O=O) = +498 kJ mol-1

2O (g) → O2 (g) E (O=O) = -498 kJ mol-1

Question 7

Aqueous solutions of acid, alkalis and salts are assumed to be largely water so you can just use the m and c values of

Answer 7

water when calculating the energy transferred.

Question 8

To calculate any changes in enthalpy per mole of a reactant or product the following relationship can be used:

Answer 8

∆H = m x s x ∆T

When there is a rise in temperature, the value for ΔH becomes negative suggesting that the reaction is exothermic and when the temperature falls, the value for ΔH becomes positive suggesting that the reaction is endothermic.