Acids and Bases Flashcards

1
Q

What is the oxonium ion?

A

H3O+

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2
Q

What is an Arrhenius acid?

A

An acid which ionize in water to give H+ and anions in water.

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3
Q

What is an Arrhenius base?

A

A base which ionizes to give OH- ions and cations in water.

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4
Q

What is a Brønsted-Lowry acid?

A

An acid that donates H+ ions in a reaction.

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5
Q

What is a Brønsted-Lowry base?

A

A base that accepts H+ in a reaction.

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6
Q

What is a Lewis acid?

A

A lone pair acceptor.

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7
Q

What is a Lewis base?

A

A lone pair donor.

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8
Q

What process and property does water have?

A

Autoionisation and amphoteric.

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9
Q

What is the reaction of boronic acid, B(OH)3 with water?

A

B(OH)3 + 2H2O -> H3O+ + B(OH)4-

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10
Q

State the strength of the conjugate base of a weak acid.

A

Strong

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11
Q

How can a greater distinction between the strength of strong acids be made?

A

If water is being used as the solvent, solvent levelling will occur. For greater distinction, use a weak acid which is harder to acidify.

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12
Q

When can we not assume [H3O+]=[A-]?

A

When in very dilute solution

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13
Q

What assumption can me made for very weak acids in the Ka equation?

A

[HA]initial=[HA]final, using [HA]initial-[H3O+] will be more accurate.

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14
Q

How do you work out the degree of dissociation?

A

([H3O+]/[HA]initial)x100

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15
Q

What is the equation relating Ka, Kb and Kw?

A

Ka+Kb=Kw(=14@298K)

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16
Q

What is the trend for the acidity of the hydrogen halides and what are the 2 reasons this trend occurs?

A

HI>HBr>HCl>HF

  1. The H-X bond becomes weaker down the group
  2. The stability and reactivity of X-, the higher the charge density of X-, the more stable it is in water(favouring F-) but if it has a high charge density, it can stop H3O+ moving freely so it lowers the acidity
17
Q

What 2 features to oxo acids have?

A

O-H and E=O bonds

18
Q

If an oxo acid is dibasic what does the structure contain?

A

2 O-H groups

19
Q

What is Bell’s rule?

A

For the acid HmEOn, pKa~8-5(n-m) n-m denotes the number of E=O groups

20
Q

How do halogenated organic acids compare in acidity to regular organic acids and why?

A

Halogenated organic acids are more acidic as halogens are electronegative which draws electron density towards it and makes carbons partially positive so a negative charge of a conjugate base is better stabilised.

21
Q

What process can happen to Fe(OH)3(OH2)3(s)?

A

It can be dehydrated to Fe2O3(s)

22
Q

Why is hydrated Al3+ a weaker acid than hydrated Fe3+?

A

Transition metals make stronger metal-oxygen bonds than other metals and the conjugate bases of iron can dimerise, increasing its stability.

23
Q

What are the 2 products of Al2O3 reacting amphoterically?

A

[Al(OH)4]- and [Al(OH2)4(OH)2]+

24
Q

What is the Henderson-Hasselbach equation?

A

pH=pKa+log([A-]/[HA])

25
Q

What is a back titration?

A

Where you react a substance with an excess of acid/base, then react the remaining acid/base to work how much is left and therefore how much of the substance there was.

26
Q

What will a weak acid/strong base titration graph look like and where is the equivalence point? Why is there a change in the pH of the equivalence point?

A

The lower half of the graph will move up with an equivalence point pH>7. When the acid has been neutralised the strong conjugate base remains in solution, making the solution basic

27
Q

How do you find the equivalence pH of successive ionisations of an acid?

A

Find the average of the 2 pKa values

28
Q

If an indicator is represented as HIn, when would you expect the colour of the solution to change? When does the colour actually change?

A

When [HIn]=[In-], at pH=pKin. When there is a 10:1 ratio of one form to the other form, this means the pH usually changes over 2 pH units.

29
Q

For amino acids, what is pI occur? How can this be tested?

A

The pH when an amino acid is favoured as the zwitterion with no charge. This can be tested with electrophoresis.