Quiz & Worksheet - Calculating Enthalpy Change from Study.com.
Study.com quiz and worksheet on calculating enthalpy change with multiple-choice questions and account creation prompt.
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Step-by-step solution for: Quiz & Worksheet - Calculating Enthalpy Change | Study.com
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Show Answer Key & Explanations
Step-by-step solution for: Quiz & Worksheet - Calculating Enthalpy Change | Study.com
Let's go through each question and provide the correct answers with explanations.
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Correct Answer:
✔ *The amount of energy in a product or reaction.*
Explanation:
Enthalpy (denoted as H) is a thermodynamic property that represents the total heat content of a system at constant pressure. It includes the internal energy of the system plus the product of pressure and volume. In chemical reactions, we often talk about change in enthalpy (ΔH), which measures the heat absorbed or released during a reaction. So, while it’s not exactly "how hot something feels" (that’s temperature), nor the number of moles, enthalpy refers to the energy content associated with substances involved in a reaction.
> ✘ Incorrect options:
> - "How hot something feels" → That's temperature.
> - "The amount of energy needed for a reaction to occur" → That’s activation energy.
> - "How many moles..." → That’s stoichiometry.
---
Correct Answer:
✔ *A device that burns a compound to determine the enthalpy.*
Explanation:
A calorimeter is an apparatus used to measure the amount of heat released or absorbed during a chemical reaction or physical change. One common type is a bomb calorimeter, where a sample is burned in oxygen under high pressure, and the heat released is measured by the temperature change of the surrounding water. This data is then used to calculate the enthalpy change (especially combustion enthalpy).
> ✘ Incorrect options:
> - "Measures how many calories you've eaten" → No, that’s not what a calorimeter does.
> - "A method for balancing equations" → No, that’s stoichiometry.
> - "An exercise device" → No, that’s unrelated.
---
Correct Answer:
✔ *Subtracting the total enthalpy of reactants from the total enthalpy of the products.*
Explanation:
The enthalpy change (ΔH) of a reaction is calculated using the formula:
\[
\Delta H = \sum H_{\text{products}} - \sum H_{\text{reactants}}
\]
This means you take the sum of the standard enthalpies of formation of the products and subtract the sum of the standard enthalpies of formation of the reactants.
> ✔ Example:
If the products have more stored energy than the reactants, ΔH is positive (endothermic). If less, ΔH is negative (exothermic).
> ✘ Incorrect options:
> - "Measuring how much energy the reaction requires" → That’s part of experimental methods but not the definition.
> - "Adding all enthalpies" → No, you subtract.
> - "Multiplying" → That doesn't make sense dimensionally or conceptually.
---
1. The amount of energy in a product or reaction.
2. A device that burns a compound to determine the enthalpy.
3. Subtracting the total enthalpy of reactants from the total enthalpy of the products.
These are the correct choices based on thermodynamic principles.
---
1. What is enthalpy?
Correct Answer:
✔ *The amount of energy in a product or reaction.*
Explanation:
Enthalpy (denoted as H) is a thermodynamic property that represents the total heat content of a system at constant pressure. It includes the internal energy of the system plus the product of pressure and volume. In chemical reactions, we often talk about change in enthalpy (ΔH), which measures the heat absorbed or released during a reaction. So, while it’s not exactly "how hot something feels" (that’s temperature), nor the number of moles, enthalpy refers to the energy content associated with substances involved in a reaction.
> ✘ Incorrect options:
> - "How hot something feels" → That's temperature.
> - "The amount of energy needed for a reaction to occur" → That’s activation energy.
> - "How many moles..." → That’s stoichiometry.
---
2. What is a calorimeter?
Correct Answer:
✔ *A device that burns a compound to determine the enthalpy.*
Explanation:
A calorimeter is an apparatus used to measure the amount of heat released or absorbed during a chemical reaction or physical change. One common type is a bomb calorimeter, where a sample is burned in oxygen under high pressure, and the heat released is measured by the temperature change of the surrounding water. This data is then used to calculate the enthalpy change (especially combustion enthalpy).
> ✘ Incorrect options:
> - "Measures how many calories you've eaten" → No, that’s not what a calorimeter does.
> - "A method for balancing equations" → No, that’s stoichiometry.
> - "An exercise device" → No, that’s unrelated.
---
3. How do you calculate enthalpy change?
Correct Answer:
✔ *Subtracting the total enthalpy of reactants from the total enthalpy of the products.*
Explanation:
The enthalpy change (ΔH) of a reaction is calculated using the formula:
\[
\Delta H = \sum H_{\text{products}} - \sum H_{\text{reactants}}
\]
This means you take the sum of the standard enthalpies of formation of the products and subtract the sum of the standard enthalpies of formation of the reactants.
> ✔ Example:
If the products have more stored energy than the reactants, ΔH is positive (endothermic). If less, ΔH is negative (exothermic).
> ✘ Incorrect options:
> - "Measuring how much energy the reaction requires" → That’s part of experimental methods but not the definition.
> - "Adding all enthalpies" → No, you subtract.
> - "Multiplying" → That doesn't make sense dimensionally or conceptually.
---
✔ Final Answers:
1. The amount of energy in a product or reaction.
2. A device that burns a compound to determine the enthalpy.
3. Subtracting the total enthalpy of reactants from the total enthalpy of the products.
These are the correct choices based on thermodynamic principles.
Parent Tip: Review the logic above to help your child master the concept of enthalpy worksheet.
