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Chemistry (S2) > 2.5 Acids & Bases > Flashcards

2.5 Acids & Bases Flashcards

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1
Q

What was the earlier definition of an acid?

A

Arrhenius

Acids release H+ when dissolved in water

Base releases OH- when dissolved in water

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2
Q

What are the Bronsted-Lowry definitions of acids and bases?

A

Acid = H+ donor
Base = H+ acceptor

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3
Q

How does Lewis describe acids and bases?

A

Acids = electron pair acceptor
Base = electron pair donor

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4
Q

What are the opinions on neutrality by the 3 acid base theories?

A

Arrhenius - Acids and bases can neutralise one another

Bronsted-Lowry & Lewis- Acids and bases can not reach neutrality

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5
Q

3 Strong acid examples

A

HCl
H2SO4
HNO3

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6
Q

What do strong acids do in solution?

A

Completely dissociate

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7
Q

Organic acid and bases are usually….

A

Weaker

Only partially dissociate in solution and form an equilibrium

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8
Q

What is the concentration of H+ or OH- ions released in strong acids and bases?

A

Same as concentration of starting acid or base

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9
Q

Acid + base =

A

Salt (+water)

In strong acids and bases, the base’s OH- is protonated by the H+ of the acid to produce water

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10
Q

When is water not produced in acid + base reactions?

A

When there’s weak acids or bases.

If base doesn’t contain a hydroxide, it can form a salt by accepting a proton. So water is not produced.

If base contains a carbonate or hydrogen carbonate, then CO2 is released.

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11
Q

What is a salt defined as?

A

The product of when you replace the proton component of an acid

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12
Q

What is the difference between Bronsted-Lowry and Lewis?

A

Bronsted-Lowry describes the accepting or donating of a proton.

Lewis describes accepting or donating electron pairs

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13
Q

Get head around previous slide

A
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14
Q

What are conjugate acids and bases?

A

Species that act as acids or bases in the reverse direction of reaction

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15
Q

What are conjugate pairs?

A

Species that are related but act as opposites (one as acid and other as base) on either side of the reaction

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16
Q

Learn Ka and Kb Equations

A

See pic

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17
Q

What is pH a measure of?

A

Concentration of H+

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18
Q

pH =

A

pH = -log10 [H+]

eg. 1 × 10^-6 M = pH 6

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19
Q

pOH =

A

pOH = - log10[OH-]

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20
Q

Low pH =

A

Stronger acids
Ka and [H3O+] increase

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21
Q

Higher pH =

A

Stronger bases
Kb and pH increase

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22
Q

pKw =

A

pKw = pH + pOH = 14

REMEMBER

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23
Q

What is an indicator?

A

A weak acid molecule that changes colour with the change of equilibrium position

The indicator’s energy levels change significantly when it’s protinated 2hich changes its colour

24
Q

[H+] produced from a strong acid =

A

Starting concentration of the strong acid

In monoprotic acids

25
Q

Who do u work out pH of a weak acid?

A

By working out the Ka

26
Q

What is the 1st assumption used when calculating pH of a WEAK acid?

A

The only thing producing H+ is the dissociation of acid

This means H+ = A-

27
Q

What is the 2nd assumption used when calculating pH of a WEAK acid?

A

The acid dissociation is really small so…
The starting concentration = equilibrium concentration

28
Q

The amine group of an amino acid is…

A

A weak base

29
Q

The carboxylic group of an amino acid is….

A

A weak acid

30
Q

What does the degree of dissociation in an amino acid depend on?

A

The pH of the solution relative to their Ka

31
Q

When pH < pKa

A

It’s more acid
Functional group more protonated than unprotonated

32
Q

When pH = pKa

A

Functional group is 50/50
Protonated = unprotonated

33
Q

When pH > pKa

A

The functional group is more deprotonated

34
Q

Knowing if a molecule is ionised at a particular pH, allows a pharmacologist to predict…

A

How easily something is absorbed

And how soluble it is

(These are important properties for understanding the behaviour of a drug)

35
Q

Learn graph shapes

A

See pic

36
Q

What do buffers rely on? And what do they do?

A

They rely on le chateliers principle to maintain pH of a system against external change.

This change can be addition of acids of bases

37
Q

What are buffers formed from

A

Weak acids or weak bases

38
Q

What does the buffer capacity of a solution depend on?

A

How much of the acid and how much of the conjugate base (HA and A-) you have present

39
Q

What are buffers used for in labs?

A

To hold experiments at certain pH

40
Q

How is the pH of a buffer calculated?

A

Using the Henderson Hasselbalch equation

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

41
Q

Where is bicarbonate used as a buffer?

A

Lungs and kidney
It buffers acids produced by metabolism and respiration

42
Q

What is looked for in blood tests to check for Acidosis OR Akolosis?

A

pH of blood & Concentration of anions in the body’s buffer system

43
Q

What is the Haemoglobin buffer system in blood important for?

A

Carbon dioxide

44
Q

What acts as buffer in intracellular fluid?

A

Amino acids of proteins can be protonated or unprotonated as a result of change in pH

And phosphates

45
Q

What is used as buffers in the kidney?

A

Ammonia
Ammonium
Phosphates

Longer response period

46
Q

What buffer systems are present in bones?

A

Inorganic components of skeleton are basic. A prolonged acidosis, will cause leaching of calcium and phosphates from skeleton

47
Q

What maintains pH in the blood?

A

Bicarbonate in blood plasma
Rapidly responding- dependant on amount of CO2 breathed out

48
Q

What is the product of CO2 dissolving in water?

A

Carbonic acid, H2CO2

49
Q

What can change the blood’s pH?

A

Restricted exchange of CO2

50
Q

What happens when too much CO2 is breathed out (hyperventilation) due to panicking?

A

H2CO3 is lost
Blood becomes slightly Alkaline
Can pass out as respiratory drive resets

51
Q

What happens when breathing is restricted?

A

Too much CO2
Too much carbonic acid
Too high a pH

52
Q

Metabolic acidosis happens from?

A

Build up of other Acidic waste products

53
Q

What can u get oalic acid from?

A

Poisoning
Ingestion
Metabolism of ethelene glycol

54
Q

Diabetic keto acidosis signs

A

Very slow very deep breathing - to exchange more CO2

55
Q

What parts of proteins can be protonated?

A

Haemoglobin and intracellular proteins (Histidine)

56
Q

Which amine can be protonated?

A

Lysine
It can form reversible bond with CO2 - this changes affinity of haemoglobin to transport O2

Chemistry (S2) (9 decks)

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