x Flashcards

1
Q

what is an alkali?

A

soluble base

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2
Q

define a Bronsted- Lowry acid

A

proton donor

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3
Q

define a Bronsted- Lowry base

A

proton acceptor

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4
Q

conjugate acid- base pair

A

contains 2 species that can be interconverted by transfer of a proton

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5
Q

monobasic acid definition

A

donates 1 proton

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6
Q

dibasic acid definition

A

donates 2 protons

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7
Q

tribasic acid definition

A

donates 3 protons

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8
Q

acid + metal

A

salt + hydrogen

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9
Q

acid + carbonate

A

salt + water + carbon dioxide

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10
Q

acid + base

A

salt + water

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11
Q

acid + alkali

A

salt + water

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12
Q

define pH

A

pH=-log[H+(aq)]

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13
Q

define [H+(aq)]

A

[H+]=10^-pH

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14
Q

what is a strong acid?

A

fully dissociates in aqueous solution

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15
Q

how can the pH of a strong acid be calculated?

A

directly from the concentration of the acid

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16
Q

what is a weak acid?

A

partially dissociates in aqueous solution

17
Q

write the general form for the dissociating of any weak acid, HA

A

HA(aq) ⇄ H+(aq) + A-(aq)

18
Q

acid dissociation constant, Ka equation

A

Ka= [H+(aq)][A-(aq)]/[HA(aq)]

19
Q

what are the units for Ka?

A

moldm⁻³

20
Q

how are Ka and pKa linked?

A

pKa=-logKa

21
Q

write the general form for the dissociating of any weak acid, HA

A

HA(aq) ⇄ H+(aq) + A-(aq)

22
Q

the stronger the acid…

A
  • larger the Ka value

- smaller the pKa value

23
Q

the weaker the acid…

A
  • smaller the Ka value

- larger the pKa value

24
Q

the weaker the acid…

A
  • smaller the Ka value

- larger the pKa value

25
Q

how do you calculate the [H+] of a weak acid?

A

[H+]= √(Ka X [HA(aq)])

pH=-log[H+]

26
Q

write a Ka equation for HA(aq) ⇄ H+(aq) + A-(aq)

A

Ka= [H+][A-]/ [HA]

27
Q

what is the simplified version of Ka expression

A

Ka= [H+]²/ [HA]

28
Q

how do you calculate the [H+] of a weak acid?

A

[H+]= √(Ka X [HA(aq)])

pH=-log[H+]

29
Q

what is Kw also called?

A

ionic product of water

30
Q

write the expression for Kw

A

Kw= [H+(aq)] [OH-(a)]

31
Q

[H+] equation for water

A

[H+]= √(Kw)

32
Q

what can pH of a strong base be calculated from?

A
  • concentration of the base

- ionic product of water Kw

33
Q

what is the pH of a solution with [OH-]= 4.5X10⁻³ at 25℃?

A
calculate pOH from [OH-(aq)]
- pOH=-log[OH-(aq)]=-log(4.5X10⁻³)= 2.34
calculate pH using pH+pOH= 14
- pH=14=pOH
- pH=14-2.34=11.66
34
Q

[H+] equation for water

A

[H+]= √(Kw)

35
Q

what are the concentrations of H+ and OH- in a solution with a pH of 3.25 at 25℃?

A

find [H+(aq)]
[H+(aq)]= 10^-pH= 10^-3.25=5.62X10⁻⁴ moldm⁻³
calculate [OH-(aq)] from Kw and [H+(aq)]
Kw= [H+(aq)][OH-(aq)]=1X10⁻¹⁴
[OH-(aq)]= Kw/ [H+(aq]=1X10⁻¹⁴/ 5.62X10⁻⁴ = 1.78X10⁻¹¹

36
Q

what is the pH of a solution with [OH-]= 4.5X10⁻³ at 25℃?

A
calculate pOH from [OH-(aq)]
- pOH=-log[OH-(aq)]=-log(4.5X10⁻³)= 2.34
calculate pH using pH+pOH= 14
- pH=14=pOH
- pH=14-2.34=11.66
37
Q

the pH of 0.065 moldm⁻³ propanoic acid, CH₃CH₂COOH is 3.04.calculate Ka

A

find [H+(aq)]
[H+(aq)]=10^-pH=10^-3.04=9.12X10⁻⁴ moldm⁻³
calculate Ka from [H+(aq)] and [HA(aq)]
Ka= [H+][CH₃CH₂COO-]/[CH₃CH₂COOH]
Ka=[H+]²/[CH₃CH₂COOH]
Ka= (9.12X10⁻⁴)²/0.065= 1.28X10⁻⁵ moldm⁻³

38
Q

calculate the pH of 0.0245 moldm⁻³ ethanoic acid, CH₃COOH at 25℃, where Ka=1.7X10⁻⁵ moldm⁻³.

A
calculate [H+(aq)] from Ka and [HA(aq)]
Ka= [H+][CH₃COO-]/ [CH₃COOH]
Ka= [H+]²/ [CH₃COOH]
[H+(aq)]=√Ka X [CH₃COOH]= √(0.0245 X 1.7 X 10⁻⁵)
= 6.45X10⁻⁴ moldm⁻³ 
find pH
pH=-log[H+]=-log(6.45X10⁻⁴)= 3.19