CP7 Measuring Enthalpy Changes

• What unit is enthalpy change measured in?

  kJ/mol
• Match the type of reaction with its enthalpy change and temperature change in the surroundings:

  Exothermic ↔️ ΔH < 0, Temperature increases

  Endothermic ↔️ ΔH > 0, Temperature decreases
• What type of enthalpy change do endothermic reactions have?

  Positive
• What is the sign of ΔH for endothermic reactions?

  Positive
• Endothermic reactions decrease the temperature of the surroundings.


  True
• Steps to use a calorimeter in a chemical reaction:

  1️⃣ Prepare the calorimeter

  2️⃣ Measure initial temperature

  3️⃣ Conduct reaction

  4️⃣ Measure final temperature

  5️⃣ Calculate heat

  6️⃣ Calculate enthalpy change
• What formula is used to calculate enthalpy change (ΔH) in a calorimeter experiment?

  ΔH = q/n
• The specific heat capacity of water is 4.18
• The enthalpy change determines whether a reaction is exothermic or endothermic
• Steps in measuring enthalpy change using a calorimeter

  1️⃣ Prepare reactants

  2️⃣ Set up calorimeter

  3️⃣ Record initial temperature

  4️⃣ Mix reactants

  5️⃣ Monitor temperature change

  6️⃣ Calculate enthalpy change
• Exothermic reactions have a positive enthalpy change.

  False
• Steps in using a calorimeter to measure heat change

  1️⃣ Prepare the calorimeter

  2️⃣ Measure initial temperature

  3️⃣ Conduct reaction

  4️⃣ Measure final temperature

  5️⃣ Calculate heat

  6️⃣ Calculate enthalpy change
• What does the heat (q) calculation determine in calorimetry?

  Energy transferred during reaction
• A calorimeter measures heat absorbed or released during a reaction at constant pressure.

  True
• Match the apparatus/material with its purpose:

  Thermometer ↔️ Measures temperature changes

  Beaker ↔️ Prepares reactants

  Measuring Cylinder ↔️ Measures volumes of reactants

  Stirring Rod ↔️ Ensures uniform mixing
• The calorimeter must be well-insulated to prevent heat loss or gain
• Steps in the experimental procedure to measure enthalpy change:

  1️⃣ Prepare reactants

  2️⃣ Set up calorimeter

  3️⃣ Record initial temperature

  4️⃣ Mix reactants

  5️⃣ Monitor temperature change

  6️⃣ Calculate enthalpy change
• What is the formula for calculating heat (q) in calorimetry?

  q = mcΔT
• A reaction is exothermic if ΔH is negative
• The specific heat capacity of water is approximately 4.18 J/g°C.
• What is the formula for calculating enthalpy change (ΔH) in calorimetry?

  ΔH = q/n
• In calorimetry, what unit is used to measure the amount of heat (q)?

  Joules
• What can be done to improve the accuracy of enthalpy change measurements in calorimetry?

  Address sources of error
• What is enthalpy change denoted by?

  ΔH
• Endothermic reactions absorb heat from the surroundings, increasing the system's enthalpy
• Exothermic reactions release heat to the surroundings, causing a rise in temperature
• The ΔH value for exothermic reactions is negative.


  True
• What happens to the temperature of the surroundings during an exothermic reaction?

  Increases
• A calorimeter is used to measure the heat absorbed or released during a chemical reaction at constant pressure
• What formula is used to calculate heat (q) in a calorimeter experiment?

  q = mcΔT
• The heat (q) calculated in a calorimeter experiment represents the energy transferred during the reaction.


  True
• Enthalpy change is measured in kJ/mol.


  True
• The calorimeter must be well-insulated to prevent heat loss or gain.

  True
• Match the process with its enthalpy change:

  Exothermic ↔️ Negative ΔH

  Endothermic ↔️ Positive ΔH
• In exothermic reactions, the temperature of the surroundings increases
• In the heat calculation formula, ΔT represents the change in temperature
• The enthalpy change indicates whether a reaction is exothermic or endothermic.


  True
• The enthalpy change (ΔH) indicates whether a reaction is exothermic or endothermic
• Steps for using a calorimeter to measure enthalpy change:

  1️⃣ Prepare the calorimeter

  2️⃣ Measure initial temperature

  3️⃣ Conduct reaction

  4️⃣ Measure final temperature

  5️⃣ Calculate heat

  6️⃣ Calculate enthalpy change
• What should you ensure when preparing a calorimeter for an experiment?

  It's clean and dry