Thermochemistry

Question 1

Photosynthesis - energy process

Answer 1

(1) takes energy from sun - electromagnetic
(2) converts into chemical (potential) energy
(3) produce glucose and oxygen

Question 2

Cellular Respiration - energy process

Answer 2

(1) consumes potential energy from plants
(2) produces carbon dioxide and water, converts into chemical (kinetic) energy

Question 3

Biogenic Hypothesis

Answer 3

suggests fossil fuels had origins in deposits of plants and animals, photosynthesis stored solar energy, animals ate and stored as chemical potential energy, time temperature and pressure converted potential energy into hydrocarbons

Question 4

4 Major Fossil Fuel Demands

Answer 4

heating, transportation, industry, and commercial + institutional

Question 5

Calorimetry Assumptions

Answer 5

• energy lost or gained is gained or loss by calorimeter (isolated)
• all material is conserved (isolated)
• specific heat capacity of water and dilute solutions is 4.19J/(gxC)
• density of dilute solution is same as water 1g/mL
  -thermal energy gained or lost by rest of calorimeter is negligible

Question 6

Kinetic Energy Forms

Answer 6

• moving electrons within atoms
• vibration of atoms connected by chemical bonds
• rotation and translation of molecules made up of these atoms

Question 7

Potential Energy Forms

Answer 7

• stored in covalent/ionic bonds between entities
• intermolecular forces between entities

Question 8

Hess’ Law - Definition

Answer 8

the addition of chemical equations yields a net chemical equation whose enthalpy change is the sum of the individual enthalpy changes

Question 9

Collision Reaction Theory

Answer 9

• chemical samples consist of entities in constant random motion which rebound elastically from one another
• chemical reaction must involve collisions of reactant entities
  -effective collision requires sufficient energy and sufficient orientation
• ineffective collisions involve entities that rebound elastically from the collision

Question 10

Activation energy

Answer 10

energy barrier that must be overcome for a chemical reaction to occur

Question 11

Ozone

Answer 11

• formed and destroyed naturally by UV radiation provided by our sun (activation energy)
• formed by converting molecular oxygen into atomic oxygen (O), uses UVC radiation
• split when absorbing UVB radiation
• activation energy for destroying ozone (UVB) is lower than converting molecule (UVC)

Question 12

Catalyst

Answer 12

substance that increases the rate of a chemical reaction without being consumed itself, provides alternative , lower, energy pathway

Question 13

Enzyme

Answer 13

compound which acts as a catalyst in living systems

Question 14

Reaction Mechanism

Answer 14

Describes individual steps and intermediates formed during a reaction

Question 15

Intermediates

Answer 15

chemical entities that form with varying stability at the end of a step in a reaction mechanism, do not appear in final mixture, have lower potential energy than activated complexes