Chem 30 Unit 1

Question 1

the original source of energy on earth is….

Answer 1

the sun

Question 2

chemical energy

Answer 2

energy released when substances undergo a chemical reaction (e.g. combusion) to transform into other substances (e.g. burning of fossil fuels)

Question 3

Nuclear energy

Answer 3

form of energy released from the nucleus of atoms.

Question 4

nuclear fission

Answer 4

the splitting of an atomic nucleus into two smaller nuclei (releasing nuclear energy)

Question 5

nuclear fusion

Answer 5

combining two atomic nuclei to produce one larger nucleus (releasing nuclear energy)

Question 6

solar energy

Answer 6

energy from teh sun

Question 7

geothermal energy

Answer 7

heat energy from the earth (e.g. geysers, hotsprings)

Question 8

Laws of Thermodynamics

Answer 8

1. Law of Conversation of Energy
2. Law of Heat Exchange or Transfer
3. Total heat lost = total heat gained

Question 9

Law of Conversation of Energy

Answer 9

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

Question 10

Law of Heat Exchange or Transfer

Answer 10

Heat flows from hot to cold until thermal equilibrium

Question 11

Total heat lost = total heat gained

Answer 11

energy lost by the hot object is equal to the energy gained by the cold object.

Question 12

Exothermic

Answer 12

energy produced, given off by the reactants. Releases heat to the surroundings. Has a negative ΔH.

Question 13

Endothermic

Answer 13

energy is required, reaction needs energy to occur. Absorbs energy from the surroundings. Has a positive ΔH.

Question 14

cellular respiration is…

Answer 14

exothermic

Question 15

photosynthesis is…

Answer 15

endothermic

Question 16

Kinetic molecular theory

Answer 16

the smallest particles of any substance are in continuous motion

Question 17

translational motion

Answer 17

straight line motion (gases)

Question 18

rotational motion

Answer 18

spinning or turning (liquids)

Question 19

vibrational motion

Answer 19

oscillation (back/forth) motion (solids)

Question 20

temperature is …

Answer 20

the average kinetic energy of the particles of the substance.

Question 21

Change in temperature =

Answer 21

change in average kinetic energy

Question 22

specific heat capacity

Answer 22

the quantity of heat required to raise/lower the temp of a substance per unit mass per degree celsius.

Question 23

calorimetry

Answer 23

a substance is burned in pure oxygen in a reaction chamber. heat released flows into surrounding water, changing its temperature. use data collected to calculate heat given off.

Question 24

Enthalpy (ΔH):

Answer 24

measure of the energy content of a system

Question 25

open system

Answer 25

allows both energy and matter to flow in and out of the system

Question 26

closed system

Answer 26

only allows the transfer of energy in and out (does not allow transfer of matter)

Question 27

enthalpy of a system is

Answer 27

the total kinetic energy and potential energy of a system under constant pressure

Question 28

kinetic energy

Answer 28

energy of an object due to motion (change in temp)

Question 29

potential energy

Answer 29

energy of an object due to position (chemical change)

Question 30

molar enthalpy

Answer 30

= molar heat of combustion

Question 31

molar enthalpy/molar heat is...

Answer 31

positive/negative depending on if water was heated/cooled

Question 32

positive enthalpy change means....

Answer 32

endothermic reaction

Question 33

negative enthalpy change means....

Answer 33

exothermic reaction

Question 34

for calorimetry questions that include both the water and calorimeter...

Answer 34

chemical energy = calorimeter (water + calorimeter)

Question 35

molar enthalpies for decomposition

Answer 35

switch sign of data book value

Question 36

potential energy diagrams...

Answer 36

shows the change in potential energy during a chemical reaction.

Question 37

in an exothermic potential energy diagram...

Answer 37

there is a step down (reactants have more Ep than products)

Question 38

in an endothermic potential energy diagram...

Answer 38

there is a step up (reactants have less Ep than products)

Question 39

Axis for a potential energy diagram:

Answer 39

x axis: progress of reaction y axis: potential energy (Ep)

Question 40

difference between the Ep of reactants and products =

Answer 40

ΔH (change in enthalpy)

Question 41

catalyst

Answer 41

makes the reaction happen faster, but does not hange the reaction. Does not change the ΔH.

Question 42

Activation energy

Answer 42

energy needed to get the reaction started (do not include when calculating ΔH in a Ep diagram).

Question 43

Hess's Law

Answer 43

the enthalpy of reaction is the same regardless of whether a reaction occurs in one step or in several steps.

Question 44

ΔH =

Answer 44

products - reactants

Question 45

ΔH of elements =

Answer 45

0 kJ