Chapter 6 - Thermochemistry

Question 1

To convert from L atm to Joules

Answer 1

Multiply by 101.3 J

Question 2

Radiant energy

Answer 2

Comes from the sun

Question 3

Thermal energy

Answer 3

Energy associated with the random motion of atoms and molecules

Question 4

Chemical energy

Answer 4

Energy stored within the bonds of a chemical substance

Question 5

Nuclear energy

Answer 5

Energy stored within the collection of neutrons and protons in the atom

Question 6

Potential energy

Answer 6

Energy available by virtue of an objects position

Question 7

What is heat?

Answer 7

The transfer of thermal energy between two bodies that are at different temperatures

Question 8

Define thermochemistry

Answer 8

The study of heat change and chemical reactions

Question 9

Define the system

Answer 9

The specific part of the universe that is of interest in the study

Question 10

Define the surrounding in thermochemistry

Answer 10

The rest of the universe outside the system

Question 11

Exothermic process

Answer 11

Any process that gives off heat (from system to surrounding)

Question 12

Endothermic process

Answer 12

Any process in which heat has to be supplied to the system from the surroundings

Question 13

Thermodynamics

Answer 13

The scientific study of the inter-conversion of heat and other kinds of energy

Question 14

State functions

Answer 14

Properties that are determined by the state of the system, regardless of how that condition was achieved (same end point two different paths)

Question 15

First law of thermodynamics

Answer 15

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

Question 16

First law of thermodynamics equation

Answer 16

🔺U = q + w

U is the change
Q is the heat exchange
W is the work done by the system

Question 17

Work done equation

Answer 17

Work = - pressure x volume (then convert to Joules)

Question 18

Convert from joules to L atm

Answer 18

Divide by 101.3

Question 19

Define enthalpy

Answer 19

Used to quantify the heat flow into or out of a system in a process that occurs at constant pressure

Question 20

Enthalpy eqaution

Answer 20

🔺H = H (products) - H (reactants)

Question 21

How many kJ are absorbed for every 1 mole of ice that melts at 0 degrees Celsius

Answer 21

6.01 kJ/mol

Question 22

How many kJ are released for every 1 mole of methane that is combusted at 25 degrees celsius

Answer 22

890.4 kJ (-890.4 kJ/mol)

Question 23

Heat released from water solid to water liquid

Answer 23

6.01 kJ/mole

Question 24

Heat released from water liquid to water solid

Answer 24

-6.01 kJ/mole

Question 25

Define specific heat

Answer 25

The amount of heat (q) required to raise the temperature of 1 g of the substance by 1°C

Question 26

Define heat capacity

Answer 26

The amount of heat (q) required to raise the temperature of a given quantity (m) of the substance by 1°C

Question 27

Formula for Heat absorbed or released

Answer 27

Q = m x s x 🔺t

m is amount of sample
s is specific heat
t is difference between ending and starting temp.