Chapter 6 Quiz

Question 1

Thermochemistry

Answer 1

The study of the relationship between chemistry & energy

Question 2

Work

Answer 2

The result of a force acting through a distance

Question 3

Heat

Answer 3

The flow of energy caused by temp. difference

Question 4

Kinetic energy

Answer 4

The energy associated with the motion of an object

Question 5

Thermal energy

Answer 5

The energy associated with the temperature of an object

Question 6

Potential energy

Answer 6

The energy associated with the position or composition of an object

Question 7

Chemical energy

Answer 7

The energy associated with the relative positions of electrons & nuclei in atoms & molecules (form of potential energy)

Question 8

Law of conservation of energy

Answer 8

States that energy can neither be created nor destroyed

Question 9

System

Answer 9

A set of substances & energy that are being studied

Question 10

Surroundings

Answer 10

Everything with which the system can exchange energy

Question 11

KE =

Answer 11

1/2mv^2
1/2(mass)(velocity^2)

Question 12

1kg m^2/s^2

Answer 12

1 joule (J)

Question 13

calorie (cal)

Answer 13

4.184 J

Question 14

Calorie (Cal)

Answer 14

4184 J

Question 15

Joules

Answer 15

SI unit of energy

Question 16

First law of thermodynamics

Answer 16

The total energy of the universe is constant / does not change

Question 17

Internal energy

Answer 17

The sum of kinetic & potential energies of all of the particles that compose the system. It is a state function

Question 18

State function

Answer 18

The value depends only on the state of the system

Question 19

ΔE =

Answer 19

E(final) - E(initial)
E(products) - E(reactants)
q + w OR heat + work

Question 20

When is ΔE positive?

Answer 20

When energy is absorbed (endothermic reaction)

Question 21

When is ΔE negative?

Answer 21

When energy is released

Question 22

Thermal equilibrium

Answer 22

There is no additional net transfer of heat

Question 23

Heat capacity (C)

Answer 23

A measure of the system’s ability to absorb thermal energy without undergoing a large change in temp OR the amount of heat required to change its temperature by 1 degree C.

Question 24

Specific heat capacity (Cs)

Answer 24

The amount of heat required to raise the temp of 1 gram of substance by 1 degree C

Question 25

Molar heat capacity

Answer 25

The amount of heat required to raise the temp of 1 mol of a substance by 1 degree C

Question 26

q =

Answer 26

m times Cs times ΔT Heat (J) = mass (g) times Specific heat capacity (J/gC) times Temp change (degrees C)

Question 27

Pressure-volume work

Answer 27

Occurs when force is caused by a volume change against an external pressure

Question 28

w =

Answer 28

f times d OR force times distance p times a times d p times a times Δh p times ΔV

Question 29

ΔE(rxn) =

Answer 29

qv+w

Question 30

Calorimetry

Answer 30

measuring the thermal energy exchanged between the reaction (or system) and the surroundings by observing the change in temp of the surroundings

Question 31

Bomb calorimeter

Answer 31

Piece of equipment designed to measure ΔE for combustion reactions

Question 32

q(cal) =

Answer 32

C(cal) times ΔT C(cal) = heat capacity of the entire calorimeter assembly

Question 33

Enthalpy

Answer 33

The sum of a system's internal energy & the product of its pressure & volume

Question 34

ΔH =

Answer 34

ΔE + PΔV the heat at constant pressure

Question 35

Endothermic reaction

Answer 35

A chemical reaction that absorbs heat from its surroundings

Question 36

Exothermic reaction

Answer 36

A chemical reaction that releases heat to its surroundings

Question 37

When is ΔH positive?

Answer 37

When it's endothermic

Question 38

When is ΔH negative?

Answer 38

When it's exothermic

Question 39

Enthalpy of reaction / Heat of reaction

Answer 39

Extensive property - depends on the amount of material undergoing the reaction. The enthalpy change for a chemical reaction

Question 40

Coffee-cup calorimeter

Answer 40

Consists of 2 styrofoam coffee cups, one inserted into the other, to provide insulation from the laboratory equipment. Equipped with a thermometer & stirrer

Question 41

Compare & contrast bomb calorimeters & coffee-cup calorimeters

Answer 41

Bomb calorimeters & coffee-cup calorimeters both measure changes in temp. However, bomb calorimeters measure ΔE & have constant volume while coffee-cup calorimeters measure ΔH(rxn) & have constant pressure

Question 42

Relationships involving ΔH(rxn)

Answer 42

1. If a chemical equation is multiplied by the same factor, then ΔH(rxn) is also multiplied by the same factor 2. If a chemical equation is reversed, then ΔH(rxn) changes signs 3. If a chemical equation can be expressed as the sum of a series of steps, then ΔH(rxn) for the overall equation is the sum of the heats of reactions for each step

Question 43

Hess's Law

Answer 43

The change in enthalpy for a stepwise process is the sum of the enthalpy changes of the steps

Question 44

Standard state

Answer 44

Pure gas at a pressure of exactly 1atm Pure liquid or solid in its most stable form at a pressure of 1atm & at the temp of interest (usually 25 degrees C) Substance in solution at a concentration of exactly 1M

Question 45

Standard enthalpy change (ΔH w/ degree sign)

Answer 45

The change in enthalpy for a process when all reactants & products are in their standard states. The degree sign indicates standard states

Question 46

Standard enthalpy (heat) of formation (ΔH(f) w/degree sign)

Answer 46

ΔH(f) w/ degree sign = 0 for a pure element in its pure state. For a pure compound: The change in enthalpy when 1 mol of the compound forms its constituent elements in their standard states

Question 47

ΔH (w/ degree sign) (rxn)

Answer 47

Sum of n(p) times ΔH (w/ degree sign) (products) - Sum of n(r) times ΔH (w/ degree sign) (reactants)

Question 48

List 3 connections between energy use & the environment

Answer 48

- Ozone production - CO2 - Solar panels