thermochemistry terms

Question 1

energy

Answer 1

the capacity of doing work or producing heat

Question 2

kinetic energy

Answer 2

the energy of motion

Ek = ½ mv2

Question 3

chemical potential energy

Answer 3

the energy stored in chemical bonds

composition or position

Question 4

heat

Answer 4

energy that flows across a temperature gradient from hot to cold (q)
Flows from high-temperature areas to low-temperature areas

Question 5

temperature

Answer 5

the measure of the average kinetic energy of the molecules in a system

Question 6

system

Answer 6

part of the universe in which we are interested in.

Question 7

surroundings

Answer 7

consists of the rest of the universe (although sometimes we can limit the surroundings to a smaller area immediately surrounding the system)
Burning a match

System: wood that Wood that’s burning

Surroundings: everything around the wood

Question 8

first law of thermodynamics

Answer 8

Energy cannot be created or destroyed. It can only be converted from one form to another

Also known as the law of conservation of energy

Another way to desc this is to say that the energy of the universe is a constant

Question 9

internal energy

Answer 9

An energy form inherent in every system

arises from the molecular state of motion of matter.

The symbol U is used for the internal energy and the unit of measurement is the joules (J)

delta E = q + w

Question 10

enthalpy

Answer 10

Enthalpy is the measurement of energy in a thermodynamic system.

all of the energy in a system

delta H or q

Question 11

calorimeter

Answer 11

a device used for heat measurements necessary for calorimetry. It mainly consists of a metallic vessel made of materials which are good conductors of electricity such as copper and aluminium etc.

Question 12

calorimetry

Answer 12

the measurement of the transfer of heat into or out of a system during a chemical reaction or physical process

Question 13

endothermic process

Answer 13

A process that absorbs heat from the surroundings

POSITIVE!!

Question 14

exothermic process

Answer 14

A process that releases heat tot he surroundings

NEGATIVE

Question 15

q positive (+)

Answer 15

Heat flows from surroundings to system; heat is absorbed by system

Question 16

q negative (-)

Answer 16

Heat flows from system to surroundings; heat is given off

Question 17

W positive (+)

Answer 17

Work done on system by surroundings

Question 18

W negative (-)

Answer 18

Work done by system on surroundings

Question 19

fusion

Answer 19

solid to liquid

Question 20

solidification

Answer 20

liquid to solid

Question 21

vapourization

Answer 21

liquid to gas

Question 22

condensation

Answer 22

gas to liquid

Question 23

thermochemistry

Answer 23

The chemistry of heat and heat-associated chemical phenomena.

Question 24

sublimation

Answer 24

solid to gas (dry ice)

Question 25

deposition

Answer 25

gas to solid

Question 26

intermolecular forces

Answer 26

Intermolecular forces are responsible for most of the physical and chemical properties of matter.

holds together the particles that make up liquids and solids

Question 27

heat capacity

Answer 27

the amount of heat required to change a substance’s temperature by one degree.

Question 28

specific heat capacity

Answer 28

the amount of heat per unit of mass that is needed to raise the temperature of the substance by 1 degree Celsius.

Question 29

molar heat of vapourization

Answer 29

the energy needed to vaporize one mole of a liquid

Question 30

heat of combustion

Answer 30

the amount of heat liberated when a given amount of the substance undergoes combustion

Question 31

heat of reaction

Answer 31

the change in the enthalpy of a chemical reaction that occurs at a constant pressure

ΔH=q

Question 32

molar heat of fusion

Answer 32

the amount of heat necessary to melt 1.00 mole of a substance at its
melting point

no temperature change!!

Question 33

molar heat of solidification

Answer 33

the heat released by one mole of that substance as it is converted from a liquid to a solid

Question 34

molar heat of solution

Answer 34

the heat absorbed or released when one mole of the substance is dissolved in water.

Question 35

work

Answer 35

The expenditure of energy and how it is transferring

work and heat are ways of transferring energy from one system to another.

Question 36

specific heat for water

Answer 36

4.18

Question 37

enthalpy changes during bonds breaking phase change

Answer 37

gains energy!! endothermic!

Question 38

enthalpy changes during bonds forming phase change

Answer 38

loses energy!! exothermic

Question 39

change in potential and kinetic energy during heating up

Answer 39

Potential energy–constant

kinetic energy–increasing

Question 40

change in potential and kinetic energy during phase change

Answer 40

potential energy–increasing

kinetic energy–constant

Question 41

process behind an endothermic reaction

Answer 41

If strong bonds break, there will be a large increase in Ep
If, in turn, weak bonds form, there will be a small decrease in Ep
The net Ep will be greater
Therefore, ∆H reaction = (+)

Question 42

process behind an exothermic reaction

Answer 42

A little, a small increase in Ep will break weak bonds

If strong bonds form, a lot of energy will be released relative to the amount of energy to break the bonds of reactants, therefore there will be a large decrease in Ep

Overall, there is more energy release than absorbed and a net decrease in Ep

Question 43

standard state

Answer 43

100. kPa pressure

25 C