How to Calculate Enthalpy Change with a Coffee Cup Calorimeter

TL;DR

To calculate the enthalpy change using a coffee cup calorimeter, measure the temperature change of the water after dissolving a substance, like calcium chloride. Use the formula q = m * c * ΔT to find the heat absorbed and divide by the moles of the substance. A rising temperature indicates an exothermic reaction, while a falling temperature shows an endothermic reaction.

Transcript

in this video we're going to talk about how to solve the coffee cup calorimeter problem so let's consider this problem that's on the board 15 grams of calcium chloride is dissolved in 250 milliliters of water in a coffee cup calorimeter the temperature increases from 25.2 celsius to 35.7 and our goal is to calculate the enthalpy change in kilojoule... Read More

Key Insights

• 💘 A coffee cup calorimeter is an effective tool for measuring enthalpy changes in chemical reactions.
• 💦 The temperature change in the water indicates whether the reaction is exothermic or endothermic.
• 🥵 The enthalpy change is calculated by dividing the heat energy absorbed by the water by the number of moles of the substance.

Questions & Answers

Q: How does the coffee cup calorimeter work to measure enthalpy change?

The styrofoam cup insulates the system, preventing heat transfer. The temperature change in the water indicates whether the reaction is exothermic or endothermic.

Q: How is the enthalpy change calculated for the reaction?

The enthalpy change is calculated by dividing the heat energy absorbed by the water by the number of moles of calcium chloride.

Q: Why is the enthalpy change negative for the dissolution of calcium chloride?

The negative sign indicates that the reaction releases heat. The dissolution of calcium chloride is an exothermic process.

Q: How is the mass of water converted to grams?

The density of water is approximately one gram per milliliter, so the mass of water is equal to its volume in milliliters.

Summary & Key Takeaways

• The video explains how to use a coffee cup calorimeter to measure the enthalpy change for the dissolution of calcium chloride.

• The coffee cup calorimeter consists of a styrofoam cup, water, calcium chloride, and a thermometer.

• The temperature change in the solution indicates whether the reaction is exothermic or endothermic.