Lecture 1- Chemical Reactivity

Question 1

Definition of work.

Answer 1

The distance moved against an apposing force.

Question 2

Equation for work.

Answer 2

work= force x distance

Question 3

What is the unit of measurement for work and energy?

Answer 3

Joules

Question 4

What is 1 joule equal to?

Answer 4

The amount of energy required to move 1kg substance 10cm against gravity.

Question 5

What is 1 calorie equal to?

Answer 5

The amount heat required to raise the temperature of exactly 1g of water by 1 degree Celsius.

Question 6

What is 1 calorie equal to in joules?

Answer 6

4.184 Joules

Question 7

What is potential energy?

Answer 7

Is stored energy and

energy of position

Question 8

Equation for potential energy.

Answer 8

PE= mgh
m= mass in kg
g= acceleration due to gravity
h= height in metres

Question 9

What is kinetic energy?

Answer 9

Energy of motion. Depends on both mass and velocity.

Question 10

Equation for kinetic energy

Answer 10

KE= 1/2 mv^2

m= mass in kg
v= velocity in metres/second

Question 11

What is the 1st law of thermodynamics?

Answer 11

Energy cannot be created or destroyed by any physical or chemical changes. Can only be converted from one form to another.

Question 12

What does E=mc^2 mean?

Answer 12

If mass is destroyed, energy is created. If energy is destroyed mass is created.

Question 13

Types of energy.

Answer 13

Potential energy.
Kinetic energy.
Electromagnetic energy.
Nuclear.
Chemical energy.

Question 14

How do reactions occur?

Answer 14

They occur due to collision theory. Particles must c… but not all c.. cause r…
Must be fast enough
Correct orientation

Question 15

What affects a chemical reaction?

Answer 15

Temperature, concentration and catalyst.

Question 16

What is enthalpy change?

Answer 16

The change in energy (difference between bond energies of reactants and products).
It can be measured.
△H.
△H°= H products- H reactants

Question 17

What is enthalpy?

Answer 17

The heat content of a substance at constant pressure. Is intternal energy.
This cannot be measured.

Question 18

What is the standard state of an element.

Answer 18

The form in which the element exists under conditions of 1 atmosphere and 25°C (standard conditions).

Question 19

What is the standard state of a compound?

Answer 19

Standard state of gaseous substance is pressure of 1 atmosphere.
The standard state for a pure solid or liquid is is the state it would be at 1 atmosphere.
For a substance in solution, the standard state is concentration of 1M.

Question 20

What is exothermic?

Answer 20

Products contain less energy than reactants. 
Heat is released. 
e.g. burning, respiration.
The temperature of system will rise. 
△H will be negative.

Question 21

What is endothermic?

Answer 21

Products contain more energy than reactants. 
Heat taken in. 
e.g. photosynthesis
Temperature of system will fall.
△H is positive.

Question 22

What is entropy?

Answer 22

Measures the amount of energetic disorder in a system.
Greater the disorder of randomness the greater the entropy.
S has units J per mole kelvin
△S= S final- S initial
△S total= △S system + △S surroundings

Question 23

Law of entropy.

Answer 23

Entropy tends to a maximum.

All spontaneous changes overall an overall increase in entropy.

Question 24

What is gibbs free energy?

Answer 24

Energy from a reaction free to do work.

Question 25

△G equation

Answer 25

△G= △H- T△S

T in kelvins

Question 26

△G<0

Answer 26

Reaction is spontaneous

Question 27

△G>0

Answer 27

Reaction requires energy input (not spontaneous)

Question 28

△G=0

Answer 28

System at EQM.

Question 29

△G negative

Answer 29

exergonic reaction.

Question 30

△G positive

Answer 30

endogonic reaction.

Question 31

Catabolic reactions.

Answer 31

High energy compounds to simple molecules.

respiration and ATP hydrolysis (exergonic)

Question 32

Anabolic reactions.

Answer 32

Simple subunit to complex molecule.

In steps.