BL Ch 5 Thermochemistry

Multiple Choice

Which of the following best describes the difference between work and heat as forms of energy?

• Work involves moving an object with mass, while heat involves raising the temperature of an object.

• Work and heat are the same and can be used interchangeably.

• Work is only related to chemical reactions, while heat is not.

• Heat is the ability to do work, while work is the ability to transfer heat.

Open Ended

Why is the study of thermochemistry important for understanding chemical reactions?

Open Ended

Explain how the diagrams of the cyclist and the electrostatic charges illustrate the conversion between potential and kinetic energy.

Multiple Choice

Which of the following best describes the difference between kinetic energy and potential energy as shown in the images?

• Kinetic energy is due to motion, while potential energy is due to position or composition.

• Kinetic energy is stored in chemical bonds, while potential energy is due to motion.

• Kinetic energy is only found in solids, while potential energy is only found in liquids.

• Kinetic energy and potential energy are always equal in a system.

Multiple Choice

Which of the following statements about the system and surroundings in the piston diagram is correct?

• The system includes the hydrogen and oxygen molecules, while the surroundings include the cylinder and piston.

• The system includes the cylinder and piston, while the surroundings include the hydrogen and oxygen molecules.

• Both the system and surroundings include only the hydrogen molecules.

• The surroundings include only the air outside the piston.

Multiple Choice

Which of the following equations correctly represents the calculation of work as described in the image?

• w = F × d

• w = m × v^2

• w = Q1 × Q2 / d

• w = 1/2 mv^2

Open Ended

Describe the direction of heat flow when a hot object is placed in contact with a cold object, based on the image and text.

Multiple Choice

What type of energy does the cyclist have at the top of the hill?

• Potential energy

• Kinetic energy

• Thermal energy

• Chemical energy

Open Ended

Explain how the first law of thermodynamics applies when a system loses energy to its surroundings.

Multiple Choice

According to the definition of change in internal energy, what is the formula for ΔE?

• ΔE = Efinal - Einitial

• ΔE = Einitial - Efinal

• ΔE = Efinal + Einitial

• ΔE = Efinal × Einitial

Multiple Choice

Which of the following correctly represents the relationship between the change in internal energy (ΔE), heat (q), and work (w)?

• ΔE = q + w

• ΔE = q - w

• ΔE = w - q

• ΔE = q × w

Multiple Select

Which of the following statements about the sign conventions for q, w, and ΔE are correct?

• A positive q means the system gains heat.

• A negative w means work is done by the system.

• A positive ΔE means net loss of energy by system.

• A negative q means the system gains heat.

Multiple Choice

What term describes a process in which heat is absorbed by the system from the surroundings?

• Endothermic

• Exothermic

• Isothermal

• Adiabatic

Multiple Choice

During which type of process is heat released by the system into the surroundings?

• Exothermic

• Endothermic

• Isothermal

• Adiabatic

Open Ended

Explain why the internal energy of a system is considered a state function, using the example of water reaching room temperature from either hot or cold starting points.

Open Ended

Explain the difference between a state function and a path function, using the example of energy lost by a battery as shown in the image.

Multiple Choice

Which of the following statements best explains why ΔE is the same whether a battery is shorted out or used to run a fan, but q and w differ?

• Because ΔE is a state function and depends only on the initial and final states, while q and w depend on the path taken.

• Because q and w are state functions and ΔE is not.

• Because energy is only lost as heat in both cases.

• Because the battery loses no energy in either case.

Multiple Select

Which of the following are true about pressure–volume work as described in the images?

• It occurs when a gas expands or contracts against an external pressure.

• It can be measured using a piston.

• It is independent of volume change.

• It is given by w = -PΔV.

Multiple Choice

Which equation correctly represents the relationship between enthalpy (H), internal energy (E), pressure (P), and volume (V)?

• H = E + PV

• H = E - PV

• H = PV - E

• H = E / PV

Open Ended

At constant pressure, why does the change in enthalpy (ΔH) equal the heat gained or lost by the system?

Open Ended

How do you think understanding the concepts of energy, work, and heat will help you in studying chemical reactions?