Physical Chemistry

Question 1

A chemical reaction is in equilibrium when?

Answer 1

The composition of the reactants and products remain constant indefinitely

Question 2

Units of equilibrium constant?

Answer 2

No units

Question 3

In an endothermic reaction, a rise of temperature causes?

Answer 3

an increase in K and the yield

Question 4

In an exothermic reaction a rise in temperature causes?

Answer 4

A decrease in K and the yield

Question 5

What effect does a catalyst have on the equilibrium constant

Answer 5

no effect

Question 6

What is amphoteric

Answer 6

can act as an acid or a base

Question 7

What is the Bronsted-Lowry definition of an acid

Answer 7

When a base accepts a proton the species formed is a conjugate acid

Question 8

What is the Bronsted-Lowry definition of a base

Answer 8

When an acid donates a proton the species left is called the conjugate base

Question 9

Strong acids and bases are

Answer 9

completely ionised when dissolved in water

Question 10

Weak acids and bases are

Answer 10

only partially ionised when dissolved in water

Question 11

Examples of strong acids are

Answer 11

Sulphuric Acid, Hydrochloric acid, Nitric Acid

Question 12

Examples of weak acids

Answer 12

Any carboxylic acid

Question 13

Examples of weak bases are

Answer 13

Ammonia and amines

Question 14

Examples or strong bases

Answer 14

Any group 1 hydroxide (NaOH, LiOH)

Question 15

What is an acid/base indicator

Answer 15

weak acids which change colour depending on the pH of a solution

Question 16

What is a buffer solution

Answer 16

is one in which pH remains approximately constant when small amounts of acid or base are added

Question 17

What does an acid buffer consist of

Answer 17

a solution of a weak acid and one of its salts

Question 18

what does a basic buffer consist of

Answer 18

a solution of a weak base and one of its salts

Question 19

What is the standard enthalpy of formation of a compound

Answer 19

the energy given out or taken in when one mole of a compound is formed from its elements in their standard states

Question 20

What is entropy of a system

Answer 20

the measure of disorder within the system - the larger the disorder the larger the entropy

Question 21

what happens to entropy as temperature increases

Answer 21

increases

Question 22

What is the second law of thermodynamics

Answer 22

The total entropy of a reaction system and it’s surroundings always increases for a spontaneous process

Question 23

What is the 3rd law of thermodynamics

Answer 23

the entropy of a perfect crystal at 0 K is zero

Question 24

What is the standard entropy of a substance

Answer 24

the entropy value for the substance in its standard state

Question 25

the change in free energy between reactants on products is

Answer 25

negative

Question 26

if change in G is negative then…

Answer 26

the reaction is feasible

Question 27

at equilibrium change in G equals

Answer 27

0

Question 28

what is the order of reaction

Answer 28

it is used to relate the rate of reaction to the reacting species

Question 29

solids have a … disorder

Answer 29

low

Question 30

gases have a …. disorder

Answer 30

high

Question 31

units for order 0 is

Answer 31

mol l-1 s-1

Question 32

units for order 1 is

Answer 32

s-1

Question 33

units for order 2 is

Answer 33

mol-1 l s-1

Question 34

units for order 3 is

Answer 34

mol-2 l2 s-1