Chapter 6.3: Calorimetry: Measuring the Heat of a Chemical or Physical Change

Flashcards from Chapter 6.3 of Chemistry: The Molecular Nature of Matter and Change.

Specific heat capacity (c)

The quantity of heat required to change the temperature of 1 gram of a substance by 1 K

• c = q / (m * ΔT)

• Can be rearranged to determine the heat absorbed or released, using q = mcΔT

• Very high for water, requiring much more energy than metals

Molar heat capacity (C_m)

The quantity of heat required to change the temperature of 1 mol of a substance by 1 K

• c = q / (mol * ΔT)

Calorimeter

A device used to measure the heat released or absorbed by a physical or chemical process

Coffee-cup calorimetry (constant-pressure calorimetry)

Calorimetry done with a constant pressure, particularly to measure the heat flows of different metals through the change of water temperature given a metal

• Calculated with the formula -(mcΔT)_solid = (mcΔT)_water

Solution calorimetry

This is a type of constant-pressure calorimetry measuring the relationship between a reaction’s and solution’s heat flow

• Uses the formula -q_reaction = q_solution

  • Starts with solving for q_solution utilizing the masses, specific heat, and change

  • Then can be used to find q_reaction and ratios involving quantities, ensuring correct amounts are used

Constant-volume calorimetry (bomb calorimetry)

Used to measure the heat of combustion reactions, usually involving fuels or foods

• Uses the formula q_calorimeter = C_calorimeter * ΔT_calorimeter

  • C_calorimeter represents the heat capacity of the calorimeter

  • Furthermore, q_calorimeter = -q_reaction.