T-1 Nature of Energy

Question 1

Describe how energy is stored within a chemical system

Answer 1

1. In the motion of the particles within the system
2. In the position of particles that are attracted to or repelled from each other (Intermolecular attractions)
3. In the positions of the atoms/ions within a chemical species (intramolecular attractions - chemical bonds)

Question 2

What is chemical energy?

Answer 2

Energy stored in the positions of the atoms/ions within a chemical species (intramolecular attractions - chemical bonds)

Question 3

What is thermal energy?

Answer 3

Energy stored in the motion of the particles within the system

Question 4

What is phase energy?

Answer 4

Energy stored in the position of particles that are attracted to or repelled from each other (Intermolecular attractions)

Question 5

What factors impact the amount of energy stored in a system, thermally - thermal energy?

Answer 5

1) average velocity of the particles - temperature
2) Number of particles in the system - mass

Question 6

What factors impact the amount of phase energy stored in a system?

Answer 6

1) Strength of interaction between the particles - some constant
2) Number of particles in the system - mass

Question 7

What factors impact the amount of chemical energy stored in a system?

Answer 7

1) Strength of interactions within the molecules - some set of constants
2) Number of particles in the system - mass

Question 8

List three way to transfer energy into or out of a system

Answer 8

1. Heating (heat)
2. Working (work)
3. Radiating

Question 9

Describe the process of heating.

Answer 9

Fast moving particles collide with slow moving particles. Slow moving particles speed up while fast moving particles slow down. This continues throughout the substance until themal equilibrium is reached.

Question 10

Describe the conditions that must be met in order for heating to occur.

Answer 10

There must be a difference in temperature

Question 11

What is thermal equilibrium?

Answer 11

Temperature of two substances/regions is the same. At this point there is no net trasnfer of energy through heating.

Question 12

What type of work will we consider in chemistry?

Answer 12

Expansion or contraction of a gas at constant pressure.

Question 13

Is the following process exothermic or endothermic

• A + B → C + energy

Answer 13

Exothermic

Question 14

Is the following process exothermic or endothermic

• A + B + energy → C

Answer 14

Endothermic

Question 15

Is the following process exothermic or endothermic

• A + B → C delta H is positive

Answer 15

Endothermic

Question 16

Is the following process exothermic or endothermic

• A + B → C delta H is negative

Answer 16

Exothermic

Question 17

Is the following process exothermic or endothermic

• Surroundings grow warm during the process

Answer 17

Exothermic

Question 18

Is the following process exothermic or endothermic

• Surroundings cool during the process

Answer 18

Endothermic

Question 19

Is the following process exothermic or endothermic

• Energy is brought into the system from the surroundings

Answer 19

Endothermic

Question 20

Is the following process exothermic or endothermic

• Energy is released from the system to the surroundings

Answer 20

Exothermic

Question 21

Is the following process exothermic or endothermic

• Energy is released from the system to the surroundings

Answer 21

Exothermic

Question 22

Is the following process exothermic or endothermic

• A gas expands at a constant pressure

Answer 22

Exothermic

Question 23

Is the following process exothermic or endothermic

• A gas contracts at a constant pressure

Answer 23

Endothermic

Question 24

Is the following process exothermic or endothermic

• A gas expands at a constant pressure

Answer 24

Exothermic

Question 25

Is the following process exothermic or endothermic

• A gold bar melts

Answer 25

Endothermic

Question 26

Is the following process exothermic or endothermic

• Sweat evaporates

Answer 26

Endothermic

Question 27

Is the following process exothermic or endothermic

• Water freezes

Answer 27

Exothermic

Question 28

Is the following process exothermic or endothermic

• steam condenses

Answer 28

Exothermic

Question 29

Heat of Solution

Answer 29

Enthalpy change associated with dissolving a solute in a solvent at a constant pressure

Question 30

Heat of Vaporization

Answer 30

Energy required to change a certain amount of a liquid into a gas.

Question 31

Heat of Fusion

Answer 31

Energy required to change certain amount of a solid into a liquid

Question 32

Specific heat capacity

Answer 32

Amount of energy required to change the temperature of 1 gram of a substance by 1 degree Celcius

Question 33

molar heat capacity

Answer 33

Amount of energy required to change the temperature of 1 mole of a substance by 1 degree Celcius

Question 34

Enthalpy change associated with dissolving a solute in a solvent at a constant pressure

Answer 34

Heat of Solution

Question 35

Energy required to change a certain amount of a liquid into a gas.

Answer 35

Heat of Vaporization

Question 36

Energy required to change certain amount of a solid into a liquid

Answer 36

Heat of Fusion

Question 37

Amount of energy required to change the temperature of 1 gram of a substance by 1 degree Celcius

Answer 37

Specific heat capacity

Question 38

Amount of energy required to change the temperature of 1 mole of a substance by 1 degree Celcius

Answer 38

molar heat capacity

Question 39

Equation for work of gaseous expansion or contraction

Answer 39

w = -P•(V_f-V_i) where P is atmospheric pressure in atm

Question 40

Equation for heating that occurs when a substance changes temperature

Answer 40

q = m•c•(T_f-T_i) where c is specific heat capacity of the substance

Question 41

Equation for the heating that occurs during a phase change

Answer 41

q = m•H_{phase change} where H_{phase change} is H_vap, H_fus, H_sub, etc…