Equilibrium -physical

Question 1

Equilibrium definition

Answer 1

A chemical reaction where reactant and products concentrations remain constant

Question 2

Rate equation for equilibrium

Answer 2

K= [C]^c [D]d/[A]a [B]b

Where a,b,c,d

Question 3

If the equilibrium position lies to the left

Answer 3

Products < reactants
K<1
More reactants than products

Question 4

If the equilibrium position lies to the right

Answer 4

Products >reactants
K>1

Question 5

Equilibrium constant rules

Answer 5

Not affected by concentration and pressure
When temperature increases the value of K increases for the endothermic reaction
When temperature decreases the value for K increases for the exothermic reaction

Question 6

Endothermic enthalpy change

Answer 6

Positive

Question 7

Exothermic enthalpy change

Answer 7

Negative

Question 8

Water equilibrium

Answer 8

H2O +H2O —> H3O+ +OH-

Question 9

Kw formula

Answer 9

Kw = [H3O+] [OH-]
=1.01x10^-14

Question 10

Kw rules

Answer 10

Affected by temperature

Question 11

pH formula

Answer 11

pH = -log[H+]

Question 12

H+ concentration formula

Answer 12

10^-pH

Question 13

Concentration calculation and pH calculation tips

Answer 13

Always write out the dissociation equation

Question 14

Strong acids

Answer 14

Acids that completely dissociate into ions in aqueous solution

Question 15

Strong bases

Answer 15

Bases that completely dissociate into ions

Question 16

Weak acids

Answer 16

Acids which partially dissociate into ions in aqueous solution

Question 17

Weak bases

Answer 17

Bases which partially dissociate into ions in aqueous solution

Question 18

Strong acids examples

Answer 18

Hydrochloric, nitric and sulphuric.

Question 19

Weak acids examples

Answer 19

Ethanoic, sulphurous and carbonic

Question 20

Strong bases examples

Answer 20

Metal hydroxides and oxides

Question 21

Weak bases examples

Answer 21

Ammonia and amines

Question 22

Brønsted-Lowry acids definition

Answer 22

A proton donator since H+ ions are protons

Question 23

Brønsted-Lowry bases definition

Answer 23

A proton acceptor since H+ ions are protons

Question 24

Conjugate acid

Answer 24

The proton donator in the reverse reaction

Question 25

Conjugate base

Answer 25

The proton acceptor in the reverse reaction

Question 26

Amphoteric

Answer 26

Where a substance can act as an acid and base

Question 27

Weak acids properties

Answer 27

Higher pH Lower conductivity Slower rate of reaction

Question 28

Strong acids properties

Answer 28

Lower pH Higher conductivity Faster rate of reaction

Question 29

Strong bases properties

Answer 29

Higher pH Higher conductivity Faster rate of reaction

Question 30

Weak acids properties

Answer 30

Lower pH Lower conductivity Slower rate of reaction

Question 31

Rules for neutralising strong and weak acids and bases

Answer 31

The quantities of acid and bases used in a reaction are based on the balanced equation, not in acid strength.

Question 32

Ka formula

Answer 32

[Products] / [reactants]

Question 32

Unique rule for Ka

Answer 32

Don’t put water into the equation

Question 33

pKa formula

Answer 33

-logKa

Question 33

PKa scale

Answer 33

The lower the pKa the stronger the acid

Question 33

Why is PKa better than pH

Answer 33

It isn’t affected by the dilution of water since all species are diluted by the same factor

Question 34

Ka scale

Answer 34

The higher the Ka the stronger the acid

Question 35

Weak acid and strong base salt pH

Answer 35

More than 7

Question 36

Strong acid and weak base salt pH

Answer 36

Less than 7

Question 37

Strong acid and base salt pH

Answer 37

7

Question 38

Explanation of strong base and weak acid salt pH

Answer 38

The the conjugate base ions will react with hydronium ions supplied by water equilibrium, the water equilibrium will shift to replace the hydronium ions producing an excess of hydroxide ions.

Question 39

Weak base and strong acid salt pH explanation

Answer 39

The conjugate acid ions will react with the hydroxide ions supplied by the water equilibrium, the water equilibrium will shift to replace the hydroxide ions producing an excess of hydronium ions.

Question 40

pH of weak acids formula

Answer 40

pH = 1/2pKa - 1/2logc

Question 41

Buffer solutions def

Answer 41

A solution where the pH remains constant on addition of small amounts of acid or base

Question 42

Acid buffer composition

Answer 42

A weak acid The salt of a weak acid and strong base

Question 42

pH of buffer solution

Answer 42

pH = pKa - log[acid]/[salt]

Question 42

Indicator dissociation

Answer 42

HIn + H2O —> H30+ + OH-

Question 43

Dissociation constant of indications (Kin)

Answer 43

[H3O+] [In-]/[HIn]

Question 44

Titration graph rules

Answer 44

pH changes quickly around the endpoint of reaction The endpoint is the middle of the vertical line.

Question 45

Weak acid strong base indicator

Answer 45

Change colour between 7 and 11

Question 46

Strong acid weak base indicator

Answer 46

Change colour between 3 and 7

Question 47

Colour change of indicator

Answer 47

When H+ concentration is equal to Kin

Question 48

Colour change pH range explanation

Answer 48

The colour change is distinguishable when [Hin] and [in-] are within factor of ten therefore pH =Kin +/-1