Acid-Base And pH Flashcards

1
Q

What are the three definitions of acid-base?

A

Arrenhenius
Bronsted-Lowry
Lewis Theory

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2
Q

What is the Arrhenius definition for acid and base?

A

Acid: produces hydrogen ion and an ion in water.
Base: produces hydroxide or hydroxyl ion and a cation in water.

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3
Q

What is the Bronsted-Lowry definition of acid and base?

A

Acid: a proton donor
Base: a proton acceptor

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4
Q

What is the Lewis theory definition of acid and base?

A

Acid: accepts electrons
Base: donates electrons

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5
Q

What is a Brønsted-Lowry acid-base reaction?

A

A proton is transferred from an acid to a base.

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6
Q

What is an amphirotic solvent?

A

A solvent that can act as an acid or base. (H2O)

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7
Q

What are strong acids?

A

Powerful proton donors

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8
Q

What are weak bases?

A

Conjugated base of strong acid.

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9
Q

What is a strong base?

A

High tendency to accept protons.

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10
Q

What is a weak acid?

A

Conjugate acid of a strong base.

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11
Q

What value do strong acids have for Ka?

A

Large

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12
Q

What value do weak acids have for Ka?

A

Small

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13
Q

What does a smaller pKa mean?

A

Stronger acid
Weaker base
Large Ka

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14
Q

What does a larger pKa mean?

A

Weaker acid
Strong base
Small Ka

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15
Q

What is the value of pKw?

A

14
pKa+pKb

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16
Q

How do we assess acidity?

A

Stabilisation of a conjugate base.
The more stable the conjugate base=more acidic is the compound

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17
Q

How do we assess basicity?

A

Ability to use its nonbonding electrons to combine with a proton.

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18
Q

What influences acidity and basicity?

A

Electronegativity
Bond energy
Inductive effects
Hybridisation effect
Resonance/ Delocalisation effects

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19
Q

How does the increase of electronegativity influence acidity and basicity?

A

Increase acidity by stabilising negative charge of the conjugate base.
Decrease basicity as electrons of more electronegativity are less likely to be donated to a proton.

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20
Q

How does bond energy influence acidity?

A

Increase as its able to disperse the negative charge over the atom weakening the bond strengths.

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21
Q

How does inductive effect influence acidity?

A

Increase.

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22
Q

How does the hybridisation effect influence acidity and basicity?

A

sp,sp2 and sp3 increase acidity
sp3,sp2 and sp increase basicity

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23
Q

How does resonance/ delocalisation effects influence acidity?

A

Increase

24
Q

How does a strong acid respond in water?

A

Completely ionise

25
Q

How does a strong base react in water?

A

Completely dissociate

26
Q

How do weak acids respond in water?

A

Not completely ionised

27
Q

How do weak bases respond in water?

A

Not completely dissociate in water

28
Q

What is the equation for Kw?

A

Kw=[H3O+][OH-]=10*-14

29
Q

What is pKa a measurement for?

A

The point where the acid is half-neutralised

30
Q

What is the outcome of increasing pH of an acid?

A

Acid becomes more ionised
pH>pKa dissociated

31
Q

What is the outcome of lowering the pH of an acid?

A

Acid becomes less ionised
pH<pKa undissociated

32
Q

What is the outcome of increasing pH of a base?

A

Base becomes less ionised
pH>pKa undissociated

33
Q

What is the outcome of lowering the pH of a base?

A

Base becomes more ionised
pH<pKa dissociated

34
Q

What is the equation for a neutralisation reaction?

A

Acid+ base—> Salt+ water

35
Q

What happens to salt in a hydrolysis reaction?

A

Salt dissociate completely in water to reform the acid and base

36
Q

What does a strong acid and strong base make?

A

Neutral Salt

37
Q

What does a strong acid and weak base make?

A

Acidic salt

38
Q

What does a weak acid and strong base make?

A

Basic salt

39
Q

What is made when a neutral salt is put in water?

A

Neutral solution

40
Q

What is made when acidic salt is put in water?

A

Acidic solution

41
Q

What is made when basic salt is put in water?

A

Basic solution

42
Q

What are acid-base titrations used for?

A

Quantitative analysis of the concentration of an unknown acid or base solution

43
Q

What is the equivalence point in a titration mean?

A

Acid and base are in equal stoichiometric amounts

44
Q

What is the half equivalence point in acid base titrations?

A

Half of the total amount of base needed to neutralise the acid that has been added

45
Q

What is a buffer?

A

Solution containing two components which are weak acid and conjugate base or weak base and its conjugate acid

46
Q

What does a buffer do?

A

Resist change in pH on addition of small amount of acid or base

47
Q

What is buffer capacity?

A

The number of moles per litre of strong mono basic acid or base required to produce an increase of one pH unit in the solution

48
Q

When is the maximum buffering power?

A

When pH=pKa

49
Q

What are the different acids and bases?

A

Polyfunctional
Oxoacids
Acids and basic oxides

50
Q

What are polyfunctional acids?

A

2 ionisable groups
Difficult to dissociate more after loss of H+

51
Q

What are oxoacids?

A

Contains an OH group that ionise in water and n-m doubly bonded

52
Q

What are acidic and basic oxides?

A

Not obvious Hc donors or acceptors

53
Q

When is an acid-base titration completed?

A

Hen all the acid has been converted into its conjugated base

54
Q

What is the equivalence point of an acid-base titration?

A

Acid-base are in equal stoichiometric amounts

55
Q

What can we use pKa values for?

A

Predict the outcome of acid-base interactions