CHEM 1011

Calorimetry: The Determination of the Specific Heat of a Metal

Calorimetry

• Calorimetry – the science of measuring heat transfer.

Calorimetry

• Principle of Conservation of Energy-

Energy can neither be created nor destroyed in any process, but can be transferred from one part of a system to another

Calorimetry

• Calorimeter – device used to measure heat – calorimeter cup and thermometer.

Calorimetry

• Specific heat – the amount of heat needed to raise temperature of 1 g of a substance 1° C.

• Specific heat is an intensive property.

Calorimetry

• Specific heat values are generally lower for metals and higher for non-metals

(see Table 9.1).

Calorimetry• When a given mass of a substance

undergoes a temperature change, the equation showing the relationship between quantity of heat, specific heat, mass, and temperature change is

Q = SH x m x ΔT

ΔT = Tfinal - Tinitial

Calorimetry

• Heat lost by one substance is equal to the heat gained by the other.

Qlost = Qgained

Conclusions and Calculations

Heat Capacity of the Calorimeter

• Because calorimeter absorbs heat, must calculate Ccal.

Heat Capacity of the Calorimeter

• Construct graph and extrapolate maximum temperature.

Heat Capacity of the Calorimeter

ΔT of cold water and calorimeter = (5) – (3)

Heat Capacity of the Calorimeter

ΔT of warm water = (5) – (4)

Heat Capacity of the Calorimeter

Heat lost by warm water = (2) x 1.00cal/gºC x (7)

Heat Capacity of the Calorimeter

Heat gained by cold water & calorimeter = - (8)

Heat Capacity of the Calorimeter

Heat gained by cold water = (1) x 1.00cal/gºC x (6)

Heat Capacity of the Calorimeter

Heat gained by the calorimeter = (9) – (10)

Heat Capacity of the Calorimeter

Heat capacity of calorimeter, Ccal = (11) / (6)

Specific Heat of a Metal

Mass of metal = (3) – (2)

Specific Heat of a Metal

• Construct graph and extrapolate maximum temperature.

Specific Heat of a Metal

ΔT of cold water and calorimeter = (7) – (5)

Specific Heat of a Metal

Heat gained by calorimeter and water =

[(1) x 1.00cal/gºC x (8)] + [Ccal x (8)]

Specific Heat of a Metal

ΔT of the metal = (7) – (6)

Specific Heat of a Metal

Heat lost by the metal = - (9)

Specific Heat of a Metal

Specific heat of the metal = (11) / [(4) x (10)]

Specific Heat of a Metal

• According to the Law of Dulong and Petit,

SHmetal x gram atomic mass = 6.3 cal/moleºC

• Rearranged, it becomes

gram atomic mass = 6.3 cal/moleºC / SHmetal

Specific Heat of a Metal

Atomic mass = 6.3 cal/moleºC / (12)