1.45 pH Flashcards

1
Q

what is a hydronium ion?

A

a hydrated proton

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2
Q

what does the bronsted-lowry definition state about acids and bases?

A

acid - proton donor
base - proton acceptor

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3
Q

water is -, meaning…

A

amphoteric, it can react as an acid or a base

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4
Q

how is the dissociation of water (ionic product) represented?

A

Kw

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5
Q

what is the value of Kw at room temperature?

A

1 x 10-14

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6
Q

how does the value of the ionic product vary?

A

with temperature

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7
Q

what is formed when an acid donates a proton?

A

A conjugate base

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8
Q

what is formed when a base accepts a proton?

A

a conjugate acid

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8
Q

what is formed when a base accepts a proton?

A

a conjugate acid

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9
Q

how do strong acids/bases behave in solution?

A

completely dissociate into ions

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10
Q

how do weak acids and bases behave in solution?

A

only partially dissociate into ions

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11
Q

examples of strong acids?

A

hydrochloric, sulfuric, nitric

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12
Q

which bases are strong?

A

solutions of metal hydroxides

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13
Q

how do equimolar solutions of weak and strong acids/bases differ?

A

pH values, conductivity, reaction rates

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14
Q

what is the same about equimolar solutions of strong and weak acids/bases?

A

stoichiometry of reactions

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15
Q

how should the pH of a weak acid be calculated?

A

using pKa values

16
Q

soluble salt of strong acid strong base produces…

A

a neutral solution

17
Q

salt of weak acid strong base produces…

A

alkaline solution

18
Q

salt of strong acid weak base produces…

A

acidic solution

19
Q

how does strong acid/weak base affect the water equilibrium?

A

the weak base ion removes OH-, causing water equilibrium to shift right producing excess hydronium

20
Q

how does weak acid/strong base affect the water equilibrium?

A

the weak acid ion removes H30+, causing water equilibrium to shift right producing excess OH-

21
Q

how does strong acid/strong base affect the water equilibrium

A

neither ion has an impact so hydronium and Oh- concentrations remain equal

22
Q

what is a buffer solution?

A

one in which the pH remains approximately constant when small amounts of acid, base or water are added

23
Q

what does an acid buffer consist of?

A

a solution of a weak acid and one of its salts made from a strong base

24
Q

how does an acid buffer work?

A
  • the weak acid provides hydrogen ions (when a small amount of base removes them)
  • the salt of the weak acid provides the conjugate base which absorbs excess hydrogen ions (when a small amount of acid adds them)
25
Q

what does a basic buffer consist of?

A

a solution of a weak base and one of its salts

26
Q

how does a basic buffer work?

A

the weak base removes excess hydrogen ions
the conjugate acid provided by the salt supplies hydrogen ions when these are removed

27
Q

how is the acid indicator dissociation constant represented?

A

as Kin

28
Q

in solution the colour of a acid indicator is … from that of its conjugate base

A

distinctly different

29
Q

what is the equivalence point?

A

the midpoint of rapid increase in pH

30
Q

which indicator would be suitable for strong acid/strong base?

A

one which changes colour around pH 7

31
Q

which indicator would be suitable for strong acid/weak base?

A

one which changes colour at an acidic pH

32
Q

which indicator would be suitable for weak acid/strong base?

A

one which changes colour at basic pH

33
Q

why is it not possible to select a suitable indicator for weak acid/weak base?

A

the pH does not change rapidly enough at the end point

34
Q

indicators are…

A

weak acids

35
Q

what is the colour of the indicator determined by?

A

the ratio of HIn to In-

36
Q

what is the theoretical point at which colour change occurs?

A

when H30+ = KIn

37
Q

when is the colour change of an indicator assumed to be distinguishable?

A

when HIn and In- differ by a factor of 10

38
Q

the pH range over which a colour change occurs can be estimated be the expression

A

pH = pKIn ± 1