Lecture 7

Question 1

First law of thermodynamics

Answer 1

Total energy if system + surroundings always remains constant
Δ E (universe) = Δ E (system) + Δ E (surroundings) = 0

Question 2

State functions

Answer 2

The value of a state function depends on the state of the system not how we arrived at that state

Question 3

Name a state function

Answer 3

Internal energy

Question 4

Δ E of a chemical reaction =

Answer 4

= E products - E reactants
= q + w

Question 5

Two most important types of chemical work…

Answer 5

1. electrical
2. Pressure

Question 6

Electrical work

Answer 6

Moving charged particles

Question 7

Pressure work

Answer 7

Volume work (PV work)

Question 8

PV work

Answer 8

Work done when volume of system changes due to presence of external pressure

Question 9

Enthalpy (H) =

Answer 9

= E + PV
Δ H = Δ E + Δ PV

Question 10

Delta H ≈ Delta E

Answer 10

If a system remains at constant pressure and it’s volume does not change much

Question 11

Δ H

Answer 11

The change in heat for a system at constant pressure

Question 12

Exothermic reaction

Answer 12

• ΔH < 0
• heat is released

Question 13

Endothermic reaction

Answer 13

• ΔH > 0
• heat is absorbed

Question 14

Heat of reaction (ΔHrxn)

Answer 14

Enthapy change for chemical reaction (exothermic)

Question 15

Heat of combustion (ΔHcomb)

Answer 15

Enthalpy change for the chemical reaction when 1 moo of a substance reacts with O2 (exothermic)

Question 16

Heat of formation (ΔHf)

Answer 16

Enthalpy change for the chemical reaction when 1 mom if a compound is produced from its compone t elements (exothermic)

Question 17

Heat of fusion (ΔHfus)

Answer 17

Enthalpy change for the melting or freezing of 1 mil if a substance
Melting ΔH > 0
Freezing ΔH < 0

Question 18

Heat of vaporation (ΔHvap)

Answer 18

Enthalpy change for the vaporization or condensation of 1 mol of substance
Vaporization ΔH > 0
Condensation ΔH < 0

Question 19

Calorimetry

Answer 19

A apparatus measuring the amount of heat involved in a chemical reaction or other process

Question 20

Equation : q =

Answer 20

c x m x ΔT

Question 21

Specific heat capacity

Answer 21

The quantity of heat required to change the temperature of 1 gram of the substance by 1K (kelvin)

Question 22

Thermochemistry equation

Answer 22

A balanced equation that includes ΔHrxn

Question 23

ΔH is proportional to…

Answer 23

The amount of substance

Question 24

Decomposition

Answer 24

AB -> A + B

Question 25

Formation

Answer 25

A +B -> AB