[ CHEM1010 ] 8 - Thermochemistry

The study of heat changes in chemical reactions or physical state changes.

What is the primary focus of thermochemistry?

The ability to do work.

How is energy defined in the context of thermochemistry?

Energy that moves between two objects.

What is the definition of heat (q)?

The joule (J).

What is the SI unit of energy?

4.184 J

How many joules are equivalent to one calorie (1 cal)?

w=F⋅d

What is the formula used to calculate work (w)?

Force.

In the work formula w=F⋅d, what does the variable F represent?

Potential

Energy stored in an object due to its position or chemical composition is known as _____ energy.

The energy an object possesses because of its motion.

What is kinetic energy?

Radiant energy.

Which form of kinetic energy is created by electromagnetic waves traveling through space?

Chemical bonds.

Chemical energy is specifically energy stored in _____.

The energy of heat.

What type of energy is thermal energy?

Created; destroyed.

According to the Law of Conservation of Energy, energy cannot be _____ or _____.

One joule (1 J).

What amount of energy is required to move a 1-kilogram mass a distance of 1 meter?

1 kg⋅m²/s²

What are the base SI units of a joule (1 J)?

The energy needed to raise the temperature of 1 gram of water by 1 ∘C.

What is a calorie (cal) defined as?

A kilocalorie (kcal).

In nutrition, what is a 'food Calorie' equivalent to?

The study of energy and its interconversions.

What is thermodynamics?

The total amount of energy in the universe is constant.

What is the core assertion of the first law of thermodynamics regarding the universe?

Kinetic energy and potential energy.

Internal energy (E) is defined as the sum of which two types of energy for all particles in a system?

ΔE=Efinal​−Einitial​

What formula defines the change in internal energy (ΔE)?

The specific molecules or materials being studied.

In thermodynamics, what does the 'system' consist of?

Everything else in the universe that is not the system.

How are 'surroundings' defined in thermochemistry?

System + Surroundings.

What components make up the thermodynamic 'Universe'?

An open system.

In what type of system can both mass and energy transfer with the surroundings?

Energy can transfer with the surroundings, but mass cannot.

What is the defining characteristic of a closed system?

A system where neither mass nor energy can transfer with the surroundings.

What is an isolated system?

State function.

A property whose value depends only on the current state and not the path taken to reach it is called a _____.

It depends only on the difference in elevation, not the trail taken to reach it.

Explain why the peak height of a mountain is a state function.

No, their values depend on the specific process or path taken.

Are heat (q) and work (w) considered state functions?

ΔE=q+w

What is the mathematical definition of the first law of thermodynamics in terms of q and w?

Positive (+).

What is the sign of q when a system gains thermal energy?

Negative (−).

What is the sign of q when a system loses thermal energy?

Positive (+).

What is the sign of w when work is done ON the system?

Negative (−).

What is the sign of w when work is done BY the system?

Energy is flowing into the system.

What does a positive ΔE indicate about energy flow?

Energy is flowing out of the system.

What does a negative ΔE indicate about energy flow?

To measure the heat flow in a chemical reaction.

What is the purpose of a calorimeter?

Constant pressure.

What condition is maintained in a coffee-cup calorimeter?

Constant volume.

What condition is maintained in a bomb calorimeter?

Specific Heat Capacity (Cs​)

The heat required to raise the temperature of a specific amount of material, often used in calorimetry.

The reactants and the products.

In a chemical reaction study, what specifically constitute the 'system'?

+8 J

If a gas absorbs 20 J of heat and does 12 J of work, what is the value of ΔE?

Chemical energy is converted into kinetic energy.

When energy is converted from food to movement, what transformation occurs?

Positive (+).

What is the sign of internal energy change (ΔE) when the system adds energy and surroundings lose energy?

Final; initial.

Internal energy change depends only on the difference between the _____ and _____ states.

+22 J

If a gas releases 30 J of heat and has 52 J of work done on it, what is ΔE?

Heat.

What does the symbol q represent in thermochemistry?

Meters (m).

What unit is typically used for the variable d in the work formula w=F⋅d?

Work (w).

What is defined as energy transferred by force to move an object with mass over a distance?

The vessel itself and the air/materials in thermal contact with it.

In a chemical reaction vessel, like a beaker, what constitutes the surroundings?

Kilocalorie (kcal).

What non-SI unit is defined by the energy required to raise 1000 grams of water by 1 ∘C?

No, they are typically concerned with the change in energy (ΔE).

Is the total energy of a system (E) usually the primary concern for chemists?

Kinetic energy.

Radiant energy is a form of which broader category of energy?

Zero (ΔE_universe​=0).

What is the change in the internal energy of the universe for any process?