Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CFE - Advanced Higher Chemistry > 5) Unit 1 - Chemical Equilibrium > Flashcards

5) Unit 1 - Chemical Equilibrium Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

when is a reaction said to be in equilibrium

A

when the rate of the forward reaction is equal to the rate of the of the backward reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

name 3 things that alter the position of quilibrium

A
  • altering the concentrations of products or reactants
  • altering the temperature
  • altering pressure when their are different number of moles on product and reactant sides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

when writing the equilibrium constant K if there are pure solids or liquids what do you take their concentration as?

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe why altering concentrations of products or reactants does not affect K

A
  • only affects the position of equilibrium but not K
  • Adding more products will shift the equilibrium to the left. The system reacts to make more reactants therefore the ratio of products to reactants will be the same
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe why pressure does not effect k

A
  • only affects the position and not the k value
  • if pressure increases the equilibrium shifts to the side with the fewest gases moles
  • therefore the equilibrium reacts to restore the same ratio as product to reactants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe why changes in emperature does affect k

A
  • K is temperature dependent
  • if the forward reaction is endothermic, decreasing the temperature favours the formation of products
  • If the forward reaction is endothermic, increases in temperature favours the formation of products
  • Therefore the ratio of products to reactants is not the same as before, therefore altering the value of k
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

when would you use the ionic product of water.

A

•when you need to calculate the pH/pOH when given a concentration or pOH/pH of acid or base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what 2 formulas should you remember for the ionic product of water

A

H+ x OH- = 1x10-14

pH + pOH = 14

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

according to bronstead lowry’s definition of an acid and a base, what is an acid and what is a base

A 
ACID = ELECTRON DONOR
BASE = ELECTRON ACCEPTOR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is a conjugate acid and a conjugate base

A

conjugate acid = species left when a base accepts an electron

conjugate base = species left when an acid donates an electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

strong acids and bases completely _______ in solution.

weak acids and bases partially _______ and form an _________ which lies mostly to the left.

A

strong acids and bases completely dissociates in solution.

weak acids and bases partially dissociate and form an equilibrium which lies mostly to the left.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the general Ka, for weak acids

A

ka = [H3O+][A-]/[HA]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

the ______ the Ka, the stronger the acid

the ______ the pKA, the stronger the acid

A

the larger the ka, the stronger the acid

the smaller the pKa, the stronger the acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

formula used to work out the pH of a weak acid

A

pH = 1/2pKa - 1/2logc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what salt does a strong base and strong acid make and why

A

Neutral salt.

  • Water exists in equilibrium producing H+ and Oh- ions.
  • When the salt of a strong acid and strong base dissociates it will not react with the H+ or OH- ions in solution
  • Therefore the concentrations of H+ and OH- are equal, making it neutral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what salt does a strong base and weak acid make and why

A

BASIC

  • Water exists in equilibrium producing H+ and Oh- ions.
  • When the salt of a weak acid and strong base dissociates, one of its ions will react H+, removing them out of the equilibrium
  • This decreases the concentration of H+ in solution meaning OH-> H+. BASIC
17
Q

what salt does a weak base and strong acid make and why

A

ACIDIC

  • Water exists in equilibrium producing H+ and OH- ions
  • When the salt of a strong acid and a weak base dissociates, OH ions are removed because one of the salts ions reacts with it
  • This decreases the OH- ion concentration in solution meaning H+> OH. ACIDIC
18
Q

indicators are usually weak acids?

true or false

A

true

19
Q

what is the acid dissociation constant for an indicator ‘HIn’

A

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

20
Q

the colour of the acid molecule HIn, is the same as the colour of the conjugate base in indicators.

True or false

A

false.

They are different colours

21
Q

what formula is used to work out the pH of an indicator

A

pH = pKin + log[In-]/[HIn]

22
Q

how much greater does the In- concentration have to be compared to the HIn, for colour to dominate (colour change)

A

10x greater

23
Q

what is the equivalence point

A

the exact point when the exact amount of alkali has been added to neutralise an acid H+=OH-

24
Q

what is a buffer solution

A

solution which the pH remains the same even on the addition of small amounts of acid or alkali or water.

25
Q

What is an acid buffer

and give an example

A

solution of weak acid and one of its salt

e.g. sodium ethanoate and ethanoic acid

26
Q

how do acid buffers work on the addition of H+

A
  • H+ will react with the negative ion of dissociated salt

* the H+ are removed meaning the concentration of H+ remain the same

27
Q

how do acid buffers work on the addition of OH-

A
  • OH- will react with the H+ ion of the dissociated weak acid
  • H+ ions will remain the same, because the equilibrium will react to produce more/ replace them from the large supply of the reactant (weak acid)
28
Q

What is a basic buffer

and give an example

A

solution of weak base and one of its salts

e.g. ammonia solution and ammonium chloride

29
Q

how do basic buffers work on the addition of H+

A
  • H+ will react with OH- of dissociated weak acid
  • OH- ions will remain the same, because the equilibrium will react to produce more / replace them from the large supply of the weak acid
30
Q

how do basic buffers work on the addition of OH-

A
  • OH- will react with the positive ion of the dissociated salt.
  • The OH- ions are removed meaning the concentration of H+ and OH remain the same
31
Q

one tip should use when calculating the pH of buffer solution

A

Put in the concentrations of acid and salt, in the NEW VOLUME. (x ratio stuff)

32
Q

formula for calculating the pH of buffer solution

A

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

CFE - Advanced Higher Chemistry (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions