chapter 11: entity change (done)

Question 1

what is the basis of all change everywhere

Answer 1

energy transformation

Question 2

what is a major natural contributor to stored chemical energy

Answer 2

photosynthesis

Question 3

how is photosynthesis a natural contributor to stored chemical energy

Answer 3

• it takes energy from the sun and converts it into chemical energy
• co2 and h2o in the plant reacts to produce c6h12o6 and o2
• potential energy is then consumed by any living thing who eats it or its stored
• cellular respiration uses stored chemical energy (reverse of photosynthesis)

Question 4

biogenic hypothesis

Answer 4

• hypothesis that suggests the origin of fossil fuels
• fuels had their origins in the deposits of plant and animal material
• solar energy was captured and stored by photosynthesis
• plant matter was eaten and stored by animals or stored in the plant itself
• in certain conditions this dead plant/animal material is converted into hydrocarbons

Question 5

what are a major source of stored chemical energy

Answer 5

fossil fuels

Question 6

how to retrieve chemical energy in alberta

Answer 6

through coal, natural gas, crude oil, heavy oil, oil sands, and coal-bed methane

Question 7

perspectives regarding science and technology

Answer 7

• environmental
• economic
• legal
• ethical
• social

Question 8

what are the four major demands for energy from fossil fuels

Answer 8

• heating
• transportation
• industry
• commercial and institutional

Question 9

law of conservation of energy

Answer 9

energy is neither destroyed nor created, it is only converted from one form to another

Question 10

thermochemistry

Answer 10

the study of energy changes by a chemical system during a chemical reaction

Question 11

what is needed to study energy changes

Answer 11

isolated system

Question 12

isolated system

Answer 12

a system where energy cannot move in or out

Question 13

calorimetry

Answer 13

technological process of measuring energy changes of an isolated system called a calorimeter

Question 14

calorimeter

Answer 14

isolated system where the chemical system (reactants and products) being studied is surrounded by a known quantity of liquid (usually water) inside the calorimeter

Question 15

what type of energy is transferred between the chemical system and the water

Answer 15

heat (can only be transferred, never possessed by substances)

Question 16

what is the main assumption in calorimetry

Answer 16

no heat is transferred between the calorimeter and the outside environment

Question 17

what is the relationship of heat between the calorimeter and the chemical system

Answer 17

the heat that the chemical system loses is equal to the heat gained by the calorimeter, assuming an isolated system

Question 18

assumptions for calorimetry

Answer 18

• all the energy lost or gained by the chemical system is gained or lost (respectively) by the calorimeter; total system is isolated
• all of the material of the chemical system is conserved; total system is isolated
• the specific heat capacity of water over the temperature range is 4.19 J(g.C)
• the specific heat capacity of dilute aqueous solutions is 4.19 J/(g.C)
• the density of a dilute aqueous solution is the same as that of water; 1.00g/mL
• the thermal energy gained or lost by the rest of the calorimeter (other than water) is negligible; the calorimeter materials (stirrer, lid, container, thermometer) does not gain or lose energy

Question 19

thermal energy

Answer 19

total kinetic energy of the entities of a substance

Question 20

if the same quantity of heat was applied to different volumes of water, which would see the most difference

Answer 20

smaller quantity of water

Question 21

how is chemical energy lost calculated

Answer 21

from the thermal energy gained by the surroundings

Question 22

specific heat capacity

Answer 22

• represented by the variable c
• quantity of energy required to raise the temperature of a unit mass of a substance by one degree celsius or one kelvin
• represented by the units J/(g.C), joules over (grams multiplied by celsius)

Question 23

joule

Answer 23

energy unit , J

Question 24

how to calculate delta temperature

Answer 24

final - initial

Question 25

chemical systems have many different forms of energy, both...

Answer 25

kinetic and potential

Question 26

kinetic energies that chemical systems have involves

Answer 26

- moving electrons within atoms - the vibration of atoms connected by chemical bonds - the rotation and translation of molecules that are made up of these atoms

Question 27

chemical potential energy in chemical systems

Answer 27

- covalent or ionic bonds between the entities - intermolecular forces between entities

Question 28

enthalpy

Answer 28

- the total of the kinetic and potential energy within a chemical system - an expression of the chemical energy possessed by the chemical system

Question 29

if the reactants and products remain at the same temperature...

Answer 29

the kinetic energy of the system does not change

Question 30

how is enthalpy most often communicated

Answer 30

a difference in enthalpy between the reactants and the products for a particular chemical system

Question 31

enthalpy change

Answer 31

- (delta)H - difference between enthalpy (difference in chemical energy) of the products and the enthalpy of the reactants

Question 32

analysis of calorimetric evidence is based on what

Answer 32

- the law of conservation of energy (total energy change of chemical system is equal to the total energy change of the calorimeter) - this is why enthalpy change and thermal energy is calculated with absolute values

Question 33

what is the relationship between the surroundings and chemical system energy changes

Answer 33

energy loss by the chemical system is equal to the energy gain by the surroundings

Question 34

exothermic reaction

Answer 34

- high potential energy of chemical system - low potential energy of surroundings (water) - decrease in Ep - increase in Ek - high kinetic energy of surroundings (water) - low potential energy of chemical system

Question 35

enthalpy change of exothermic reaction has a...

Answer 35

negative enthalpy value because of a decrease in potential energy

Question 36

enthalpy change of endothermic reaction has a...

Answer 36

positive enthalpy change because of increase in potential energy

Question 37

enthalpy of a reaction

Answer 37

refers to the energy change for a whole chemical system when reactants change to products

Question 38

molar enthalpy of a reaction

Answer 38

- enthalpy change in a chemical system per unit chemical amount (per mole) of a specified chemical undergoing change in the system at constant pressure -differs from normal enthalpy as that usually goes by coefficients - kJ/mol - (delta)rHm

Question 39

endothermic

Answer 39

heat is absorbed

Question 40

exothermic

Answer 40

heat is released

Question 41

what are the four ways to communicate enthalpy change

Answer 41

- molar enthalpy of a reaction, (delta)rHm (empirical) - enthalpy changes, (delta)rH (empirical) - energy terms in balanced equations (empirical) - chemical potential energy diagrams (theoretical)

Question 42

method 1: molar enthalpies of reaction

Answer 42

- determined empirically, usually involving calorimetry - ΔfHm°, standard enthalpy values with a superscript in SATP conditions - solid and liquid compounds must have the same initial and final temperatures - ΔfHm°= ______ kJ/mol (the substance goes under the symbol) - positive enthalpy is endothermic - negative enthalpy is exothermic

Question 43

standard molar enthalpy of reactions

Answer 43

initial and final conditions of a reaction must be at SATP

Question 44

method 2: enthalpy changes

Answer 44

- writing enthalpy change beside the equation - equation ΔrH = _______KJ - if a chemical equation is altered (divided or multiplied) same thing happens to enthalpy - positive enthalpy is endothermic negative enthalpy is exothermic

Question 45

method 3: energy terms in balanced equation

Answer 45

- writing enthalpy as a product or a reactant - endothermic has enthalpy as a reactant - exothermic has enthalpy as a product - specify conditions at the end of equation

Question 46

method 4: chemical potential energy diagrams

Answer 46

- endothermic has low Ep in reactant and high Ep in product (gaining energy) - exothermic has high Ep in reactant and low Ep in products (losing energy) - reactant on left and product on right

Question 47

chemical potential energy diagram

Answer 47

shows the potential energy of both products and reactant in a reaction