Brainscape's Knowledge GenomeTM

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


See full index

Chemistry - Module 5 > 20 - Acids, bases and pH > Flashcards

20 - Acids, bases and pH Flashcards

1
Q

A Bronsted lowry acid

A

proton donor

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

A Bronsted lowry base

A

proton acceptor

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

Conjugate acid-base pairs

A
  • two species that can be interconverted by transfer of a proton
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how can water act as a base

A
  • accepts proton and becomes positive ion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

monobasic, dibasic, tribasic

A
  • Refers 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
6
Q

monobasic, dibasic, tribasic -HCL / CH3COOH / H2C02 / H3BO3

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

low value of [H+]…

A

high value of pH

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

high value of [H+]

A

low value of pH

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

how is pH measured

A

logarithmic scales of hydrogen ions

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

equation to convert H+ into pH

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

equation to convert pH into H+

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

dilution needed to convert a solution from pH 1 to pH 4

A

10 x 10 x 10 = 1000

dilution by factor of 1000

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

general equation for strong (monobasic) acid dissociation

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

for a strong acid dissociation what is special and needed for calculations

A

concentration of HA = concentration of H+

therefore - instead of using conc of H+ to find pH, can use conc of HA in -log equation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

dilution -

A
17
Q

strong and weak acids

A

fully vs partially dissociates

18
Q

Ka

A

acid dissociation constant

19
Q

Larger the value of Ka..

A

the further the equilibrium is to the right

greater dissociation and greater acid strength

20
Q

Ka formula

A
21
Q

why use pKa instead of Ka

A

Hard to compare Ka values because they have negative indices

22
Q

convert ka into pKa

A
23
Q

convert pKa into Ka

A
24
Q

if Ka increases… (effect on pKa)

A

pKa decreases

25
Q

how to calculate Ka from equilibrium concentrations

A
26
Q

approx 1 - Ka

A
  • HA dissociates to produce equilibrium concentration of H+ and A- that are equal
  • Small concentration of H+ released from dissociation of water but this will be so small, it can be neglected compared to H+ of acid

The contribution of H+ from the water is negligible.

27
Q

approx - 2 Ka

A

The dissociation of the HCOOH is small enough for the equilibrium concentration of HCOOH to be taken as the same as the initial concentration.

28
Q

problems with approx 1

A
  • If pH > 6 = then conc of H+ from dissociation of water will be significant compared to dissociation of weak acid
29
Q

problems with approx 2

A
  • Assumes that conc of acid is greater than the H+ conc at equilibrium
  • Fine for weak acids with low Ka values
  • When conc of H+ INCREASES = ‘stronger’ weak acids = it breaks down
  • Difference between conc of acid at equilibrium and conc of acid at start – conc of H+ at equilibrium

doesnt work for stronger weak acids or very dilute solutions where the difference is significant

30
Q

using approx - how can Ka be simplified for equilibrium

A
31
Q

Calculate pH from Ka

A
  • To calculate pH, need to find [H+] first.
  • Rearrange formula for H+ conc
32
Q

determination of Ka experimentally

A
  • preparing a standard solution of weak acid of known concentration
  • measuring pH of standard solution using a pH meter
  • pH= acid concentration calculation or pH measurement
33
Q

how can water be an acid and a base

A
34
Q

Kw

A

ionic product of water - conc of H+ and OH- multiplied together

35
Q

Kw - 1 x 10^-14

calculate the pH of water

A
36
Q

For pH with whole numbers how to work out conc of H+ and OH-

A

indices add up to 14

37
Q

if pH is not a whole number how to work out conc of H+ and OH-

A
38
Q

how to find pH of a strong base

A
  • as strong base - conc of base = conc of OH-
  • use OH- and Kw to find conc of H+
  • minus log it
39
Q

state the two assumptions for ka / weak acid calculations

A

The contribution of H+ from the water is negligible.

The dissociation of the HCOOH is small enough for the equilibrium concentration of HCOOH to be taken as the same as the initial concentration.

Chemistry - Module 5 (7 decks)

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