Chapter 10: Thermochemistry

Question 1

Thermochemistry

Answer 1

The study of the relationships between chemistry and energy.

Question 2

energy

Answer 2

Capacity to do work

Question 3

work

Answer 3

the result of a force acting through a distance

Question 4

heat

Answer 4

The flow of energy caused by a temperature difference.

Question 5

kinetic energy

Answer 5

The energy associated with the motion of an object.

Question 6

thermal energy

Answer 6

The energy associated with the temperature of an object. It is actually a type of kinetic energy because it arises from the motions of atoms or molecules with a substance.

Question 7

potential energy

Answer 7

The energy associated with the position or composition of an object.

Question 8

chemical energy

Answer 8

The energy associated with the relative positions of electrons and nuclei in atoms nd molecules. It is also a form of potential energy.

Question 9

law of conservation of energy

Answer 9

States that energy can be neither created nor destroyed.

Question 10

system

Answer 10

In thermodynamics, the portion of the universe that is singled out for investigation.

Question 11

surroundings

Answer 11

In thermodynamics, everything in the universe that exists outside the system under investigation.

Question 12

Thermodynamics

Answer 12

The general study of energy and its interconversions.

Question 13

First law of thermodynamics

Answer 13

The law of energy conservation which states that “the total energy of the universe is constant.”

Question 14

internal energy (E)

Answer 14

The sum of the kinetic and potential energies of all of the particles that compose the system.

Question 15

state function

Answer 15

A function whose value depends only on the state of the system, not on how the system got to that state. Internal energy is a state function.

Question 16

Change in internal energy ΔE of a chemical system

Answer 16

ΔE = E_products - E_reactants

Question 17

Energy flow between system and surroundings

Answer 17

ΔE_system = -ΔE_surroundings

Question 18

Relationship between internal energy, heat, and work

Answer 18

The change in the internal energy of the system (ΔE) is the sum of the heat transferred (q) and the work done (w).

ΔE = q + w

q (heat)

• +system gains thermal energy
• • system loses thermal energy

w(work)

• • work done on the system
• • work done by the system

ΔE (change in internal energy)

• • energy flows into the system
• • energy flows out of the system

Question 19

thermal equilibrium

Answer 19

There is no additional net transfer of heat.

q_system = - q_surrounding

Question 20

heat capacity

Answer 20

(C) The quantity of heat required to change its temperature by 1 °C.

C = q/ΔT = J/°C

Question 21

relationship between heat (q), temperature (T), and heat capacity

Answer 21

q = C x ΔT

Question 22

specific heat capacity

Answer 22

The measure of the intrinsic capacity of a substance to absorb heat. The amount of heat required to raise the temperature of 1 gram of the substance by 1°C.

Unit is J/g •°C

Question 23

molar heat capacity

Answer 23

The amount of heat required to raise the temperature of 1 mole of a substance by 1°C. Unit is J/mol•°C

Question 24

Relationship between Heat (q), Mass (m), Temperature (T), and specific heat capacity of a substance (C_s)

Answer 24

q = m x C_s x ΔT

Question 25

pressure-volume work

Answer 25

When the force is caused by a volume change against an external pressure.

Question 26

pressure

Answer 26

The force that pushes against the cylinder divided by the area of the cylinder.

Question 27

Relationship between work, pressure, and change in volume

Answer 27

w = -PΔV ## Footnote As the volume of the cylinder increases, work is done on the surroundings by the system, so w should be negative. Upon expanision, V₂ is greater than V₁ so ΔV is positive. In order for w to be negative for a positive expansion, we need to add a negative sign to our equation.