Constant-pressure calorimetry | Thermodynamics | AP Chemistry | Khan Academy

TL;DR

Calorimetry is the measurement of heat flow, and a calorimeter is used to measure heat flow. Different types of calorimetry include constant-pressure calorimetry and calorimetry for chemical reactions.

Transcript

• [Instructor] Calorimetry refers to the measurement of heat flow. And a device that's used to measure heat flow is called a calorimeter. An easy way to make a calorimeter is to use two coffee cups. So at the base here, we have one coffee cup, and then we can also use another coffee cup as a loose fitting lid. And since this top coffee cup is loose... Read More

Key Insights

• 🥵 Calorimetry is the measurement of heat flow using a calorimeter.
• 💘 Constant-pressure calorimetry can be done using a coffee cup calorimeter exposed to atmospheric pressure.
• 😘 Heat is transferred from a higher temperature substance to a lower temperature substance until thermal equilibrium is reached.
• ❓ Calorimetry can be used in chemical reactions to determine whether they are exothermic or endothermic.
• 😚 The magnitude and sign of heat flow in calorimetry indicate the direction and amount of energy gained or lost by the system and surroundings.
• 🥵 In exothermic reactions, heat is transferred from the system to the surroundings, resulting in an increase in temperature.
• 🥵 In endothermic reactions, heat is transferred from the surroundings to the system, resulting in a decrease in temperature.

Questions & Answers

Q: What is calorimetry?

Calorimetry is the measurement of heat flow, where a calorimeter is used to determine the amount of heat transferred between substances.

Q: What is constant-pressure calorimetry?

Constant-pressure calorimetry involves using a coffee cup calorimeter to measure heat flow, where the calorimeter is exposed to the constant pressure of the atmosphere.

Q: How is heat transferred in calorimetry?

In calorimetry, heat is transferred from a higher temperature substance to a lower temperature substance until thermal equilibrium is reached.

Q: How is calorimetry used in chemical reactions?

Calorimetry can be used to determine whether a chemical reaction is exothermic or endothermic by measuring the heat flow between the system and its surroundings.

Summary & Key Takeaways

• Calorimetry involves measuring heat flow, and a calorimeter is the device used for this purpose.

• Constant-pressure calorimetry can be done using a coffee cup calorimeter, where heat is transferred between a substance and water.

• Calorimetry can also be used to measure heat flow in chemical reactions, determining whether they are exothermic or endothermic.