8.1.2 Measuring Enthalpy Changes

• Enthalpy change is the heat energy released or absorbed during a chemical reaction at constant pressure
• What is an example of a reaction where enthalpy change is measured?

  Burning methane gas
• Calorimetry measures enthalpy changes during chemical reactions or physical processes.
• Bomb calorimetry is used to measure enthalpy changes in a sealed, pressurized container
• Match the calorimetry method with its description:

  Bomb calorimetry ↔️ Combustion reactions in a sealed container

  Solution calorimetry ↔️ Dissolving a solute in a solvent

  Reaction calorimetry ↔️ Chemical reactions in an open system
• What is the purpose of calorimetry techniques?

  Measure heat energy changes
• Order the three main mechanisms of heat transfer from fastest to slowest:

  1️⃣ Radiation

  2️⃣ Convection

  3️⃣ Conduction
• Heat transfer by the movement of a fluid is called convection
• What is an example of heat transfer through conduction?

  Warming a metal pot
• Thermal energy moves from a hotter object to a cooler object.
• Heat transfer through direct contact without bulk movement is called conduction
• What is an example of heat transfer through convection?

  Heating water in a kettle
• Which calorimetry method measures enthalpy changes for combustion reactions in a sealed, pressurized container?

  Bomb calorimetry
• What formula is used to calculate enthalpy change (ΔH) in calorimetry?

  \Delta H = mc\Delta T</latex>
• What is the experimental technique used to measure enthalpy changes during chemical reactions or physical processes?

  Calorimetry
• Match the calorimetry method with its description:

  Bomb calorimetry ↔️ Measures enthalpy changes for combustion reactions in a sealed, pressurized container

  Solution calorimetry ↔️ Measures enthalpy changes when a solute is dissolved in a solvent

  Reaction calorimetry ↔️ Measures enthalpy changes during a chemical reaction in an open system
• The enthalpy change (ΔH) is calculated using the formula ΔH = -m × c × ΔT
• In the formula ΔH = -m × c × ΔT, 'm' represents the mass of the solution
• What does 'c' represent in the formula ΔH = -m × c × ΔT?

  Specific heat capacity
• In the formula ΔH = -m × c × ΔT, ΔT represents the change in temperature
• Name three factors that can affect the accuracy of calorimetry measurements.

  Heat loss, incomplete mixing, uncertainties in measurements
• Order the steps in a solution calorimetry experiment:

  1️⃣ Measure the initial temperature of the water

  2️⃣ Add the solute or react the substances

  3️⃣ Measure the final temperature

  4️⃣ Calculate the enthalpy change using ΔH = -m × c × ΔT
• Heat loss to the surroundings can cause enthalpy changes to be underestimated in calorimetry experiments.
• What is the impact of incomplete mixing in a calorimeter?

  Inaccurate temperature measurements
• The heat capacity of the calorimeter itself can cause enthalpy changes to be over- or underestimated
• Match the source of error in calorimetry with its impact:

  Uncertainties in temperature measurements ↔️ Inaccurate enthalpy calculations

  Evaporation of solution ↔️ Reduced observed temperature change
• How can errors in calorimetry be minimized?

  Well-insulated calorimeters, complete mixing, high-precision thermometers