Brainscape's Knowledge GenomeTM

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


See full index

chemistry > acids and bases and PH > Flashcards

acids and bases and PH Flashcards

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

what is a bronstead lowry acid

A

a proton donor

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

what is a bronstead lowry base

A

a proton acceptor

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

what is a conjugate acid

A

it donates a proton to form the conjugate base

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

what is a conjugate base

A

it accepts a proton to form the conjugate acid

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

what is the role of water in acid- base equilibria

A

an acid can only donate a proton if there is a base to accept it . by mixing eg HCl with warer an equilibrium is set up consisiting of two acid - base conjugate pairs and a hydronium ion forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

draw a dot and cross diagram of the hydronium ion

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how would we use the hydronium ion to show neutralisation

A

H3O+ + OH- = 2H20

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

what is a polybasic acid

A

monobasic , dibasic and tribasic acids refer to the total number of hydrogen ions in the acid that can be replaced per molecule in an acid - base reaction

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

how do you calculate the amount of alkali needed for the complete neutralisation of polybasic acids

A

1) decide whether the acid is monobasic , dibasic or tribasic
2) write the equation using as many NAoh units needed to replace the hydrogen atoms in the acid
3) use the balanced equations to deduce the molar ratio of acid to alkali and carry out the calculations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what must we remeber about all bases

A

not all bases are alkalis . a base is only an alkali if it is soluble in water . eg magnesium hydroxide is a base but not an alkali

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

definition of a monobasic acid

A

one mol of a monobasic acid will release one mol of hydrogen ions in solution

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

give an example of a dibasic acid

A

carbonic acid H2CO3

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

give an example of a tribasic acid

A

H3BO3

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

what is sorensens PH scale

A

converted PH colour values to hydrogen ion concentration values

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

how do you work out PH using logs

A

PH = - log [H+]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how do you work out PH from hydrogen ion concentration

A

[H+] = 10^ - ph

17
Q

how many times greater is the [H+] for a PH of 1 than a PH of 2

A

10 times greater

18
Q

what do we know about [H+] with a small PH value

A

[H+] concentration is high and vice versa

19
Q

how come we can calculate PH for a strong acid from h+ concentration

A
  • a strong acid completely dissociates in water therefore the conentration of h+ ions is directly proportional to the acid concentration
20
Q

what are the strong acids

A

H2SO4 , HCl and HNO3

21
Q

how do we represent the dissociation of a weak acid

A

using a reversible arrow
HA(aq) = H+(aq) + A-(aq)

22
Q

which way will the equilibrium lie for a weak acid disociation

A

the equilibrium will lie to the left because they only partially dissociate. a very small concentration of H+ ions and A- ions so Kc<1

23
Q

what is the acid dissociation constant Ka

A

the extent of an acid dissociation is measured by another type of equilibrium constant Ka
- to find the equation for Ka it is the exact same as for Kp or Kc
we use it to calculate PH for a weak acid

24
Q

what does a large Ka value tell us about the degree of dissociation of an acid and therefore its strength

A
  • a large ka value would tell us it is a stronger acid because the concentration of reactants (acid) is lower than the products ( ions) and the further the equilibrum is to the right
25
Q

what does a small value of ka tell us about the strength of the acid and therefore its strength

A

equilibrium lies to the left therefore it is a weaker acid as fewer dissociation

26
Q

what changes the value of ka

A

temperature

27
Q

why do we not use ka for strong acids

A

because the value would be zero for the denominator

28
Q

what is pKa

A

pKa is used to convert ka values into easier values

29
Q

what are the equations for pka

A

Pka = -log(Ka)
Ka= 10^ -pka

30
Q

what is the correlation between the size of pka value and acid strength

A

the greater the pka value , the smaller the ka value and the weaker the acid

31
Q

what happens to pka values with dibasic and tribasic acids

A

the successive dissociations have a larger pka value as ka is lower as the dissociation is less likely to happen as we are removing a H+ from a negative ion

chemistry (23 decks)

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