Chapter 5

Question 1

Thermodynamics

Answer 1

study of energy and energy trasnfer

Question 2

Thermochemistry

Answer 2

study of energy changes that accompany transformations of matter ex. dissolution of NaOH (s) releases heat

Question 3

Studying energy changes

Answer 3

First law of thermodynamics/law of conservation of energy
- total energy of universe is constant
- energy cannot be created nor destroyed

Question 4

Can energy be transformed or converted onto other forms

Answer 4

Yes
ex. kinetic E of running water or heat energy

Question 5

system

Answer 5

the portion of the universe being studied

Question 6

surroundings

Answer 6

Everything else ex. the lab

Question 7

universe

Answer 7

= system + surroundings

Question 8

Heat (Q)

Answer 8

refers to transfer of kinetic energy, unit is J, temp in K= 0C = 273.15K

Question 9

enthalpy

Answer 9

total internal energy of a substance at a constant pressure, (delta H)

Question 10

what is an enthalpy change in a chemical reaction

Answer 10

• breaking a bond
• creating a bond

Question 11

endothermic reaction

Answer 11

results in net absorption of energy-bond breaking in reactants absorb more energy than released in the bond formation of products

Question 12

exothermic reaction

Answer 12

results in loss of energy-bond formation of products release more energy than absorbed by bond breaking in reactants

Question 13

which is energy released which is energy absorbed

Answer 13

endo- absorbed (+KJ)
exo- released (-KJ)

Question 14

delta H reaction

Answer 14

enthalpy of a reaction

Question 15

delta H

Answer 15

standard enthalpy of reaction

Question 16

what is a calorimeter

Answer 16

used to measure enthalpy changes for reactions

Question 17

Q=MC^T

Answer 17

• heat released by a reaction
  m= mass (g) of water in caliomter
  c= specific heat capacity (J/gc)
  ^T= change in temp (C= t2-t1)

Question 18

what assumptions are used with a calorimeter

Answer 18

1. no heat is transferred between the calorimeter and the outside environment
2. any heat absorbed/released by a styrofoam cup is negligible
3. dilute aqueous solutions is assumed to have a density and specific heat capacity of d= 1g/ml and c= 4.184 j/gc

Question 19

molar enthalpy equation

Answer 19

H= Q/h
- molar enthalpy of reaction (KJ/mol)

Question 20

what is bond energy

Answer 20

how much energy you have to use to pull apart atoms and break a bond

Question 21

bond energy equation

Answer 21

sum of bonds broken - sum of bonds formed

Question 22

specific heat capacity

Answer 22

indicates amount of energy needed to raise the temperature of one gram of substance by 1 degree C

Question 23

standard enthalpies of formation

Answer 23

quantity of energy absorbed or released when one mole of a compound is directly formed from its elements in their standard states

Question 24

delta HF

Answer 24

standard enthalpy of formation

Question 25

from enthalpy of formation equation

Answer 25

delta H reaction f= sum products - sum reactants