Calorimetry Concepts and Calculations

The video tutorial explains the differences between coffee cup and bomb calorimeters, focusing on how they measure energy changes. The coffee cup calorimeter measures energy at constant pressure, suitable for calculating enthalpy changes, while the bomb calorimeter measures energy at constant volume, used for combustion energy calculations. The tutorial then solves a problem involving the combustion of ethanol in a bomb calorimeter, demonstrating how to calculate the energy of combustion per mole using given data.

What is the primary difference between a coffee cup calorimeter and a bomb calorimeter?

• Both measure energy at constant volume.

• Both measure energy at constant pressure.

• Coffee cup calorimeter measures energy at constant pressure, bomb calorimeter at constant volume.

• Coffee cup calorimeter measures energy at constant volume, bomb calorimeter at constant pressure.

Why is styrofoam used in a coffee cup calorimeter?

• It is a good thermal insulator.

• It reacts with the solution to measure energy.

• It is a good conductor of heat.

• It is cheap and easily available.

What is the purpose of the combustion chamber in a bomb calorimeter?

• To cool down the reaction.

• To measure pressure changes.

• To allow expansion of gases.

• To contain the reaction at constant volume.

In a bomb calorimeter, what role do the ignition wires play?

• They absorb the released energy.

• They ignite the sample.

• They maintain constant pressure.

• They measure the temperature change.

What is the heat capacity of the calorimeter used in the ethanol combustion problem?

• 2.3 kilojoules per celsius

• 1.0 kilojoules per celsius

• 3.6 kilojoules per celsius

• 4.184 kilojoules per celsius

How is the energy absorbed by the calorimeter calculated?

• Using the formula q = mc^2

• Using the formula c delta t

• Using the formula m c delta t

• Using the formula p v delta t

What is the molar mass of ethanol used in the calculation?

• 18.015 grams per mole

• 12.01 grams per mole

• 46.068 grams per mole

• 28.05 grams per mole

How many moles of ethanol are present in 3.36 grams?

• 0.0291 moles

• 0.1458 moles

• 0.0365 moles

• 0.0729 moles

What is the energy of combustion per mole of ethanol?

• -1500 kilojoules per mole

• -1370 kilojoules per mole

• -990 kilojoules per mole

• -1200 kilojoules per mole

Why is the process considered endothermic for the calorimeter?

• Because the calorimeter releases heat.

• Because the calorimeter absorbs heat.

• Because the reaction releases heat.

• Because the reaction absorbs heat.