Acid-base Equilibrium Flashcards

1
Q

What is the equivalence point

A

When the acid and alkali are equal

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2
Q

What is the colour change and range for methyl orange

A

Red to yellow

3.1 - 4.4

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3
Q

Phenolphthalein range and colour change

A

8.3 - 10.0

Colourless to pink

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4
Q

Indicator for a strong acid and strong alkali

A

All 3

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5
Q

Indicator for strong alkali and weak acid

A

Phenolphthalein

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6
Q

Indicator for weak alkali and strong acid

A

Methyl orange

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7
Q

Indicator for weak acid and weak alkali

A

Can’t use indicator

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8
Q

Kw equation and value

A

(H+)(OH-)

10^-14 mol^2dm^-6
At 25 degrees
Constant for pure water and dilute acid

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9
Q

pKw equation

A

-logKw

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10
Q

pH equation

A

-log(H+)

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11
Q

What is a Bronsted acid

A

A proton donor

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12
Q

What is a bronsted base

A

Proton acceptor

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13
Q

What effect does temperature have on Kw

A

⬆️ temperature = ⬆️ Kw

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14
Q

What does Kw equal in terms of water

A

Kw = (H+) squared

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15
Q

What does % ionisation refer to

A

The concentration of H+

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16
Q

What is the Acidity constant (Ka) equation

A

See notes

17
Q

What is the equation for pKa

A

-logKa

18
Q

What does an increase in dissociation mean in terms of Ka and pKa

A

⬆️ dissociation = ⬆️ Ka = ⬇️ pKa = stronger acid

Strong acid fully dissociates ➡️ high conc of H+ in (aq) solution ➡️ higher Ka

19
Q

What is the basicity of an acid

A

No. Of H+ one molecule of an acid can produce in solution on complete ionisation.
Eg monobasic, dibasic, tribasic

20
Q

What is the effect upon the dissociation constant on ionisation of polyprotic acids

A

K1 > k2 > k3
Dissociation constant changes each time
Easier to remove H+ from neutral atom rather than negatively charged atom due to force of attraction

21
Q

What is the definition of a buffer solution

A

Resists changes in pH on addition of small amounts of acid or alkali

22
Q

What is and acid buffer solution made of

A

Weak acid + salt with a strong base

23
Q

What is the Henderson - Hasselbalch equation

A
pH = pKa + log (salt)/(acid) 
() = conc. 

pKa = -logKa

24
Q

What is the general equation for a buffer

A

HA 🔁 H+ + A-

HA = undissocated acid
A- = anion
H+ = hydrogen ions
25
Q

What happens when acid is added to a buffer

A
  1. Extra H+ ions added
  2. Anion of buffer reacts with H+ (A- + H+ ➡️ HA)
  3. Extra H+ removed
  4. Maintains H+ conc and pH
26
Q

What happens when alkali is added to a buffer

A
  1. Extra OH- added
  2. These react with undissociated acid in buffer (HA + OH- ➡️ A- +H2O) (they take a H off the acid)
  3. Extra OH- removed
  4. Maintains H+ conc and pH
27
Q

How do you measure the rate using the volume of gas evolved

A

See notes

28
Q

How do you measure the rate of a reaction using colorimetry

A

See notes

29
Q

Describe how you would measure the rate of a reaction by change in mass

A

See notes

30
Q

Describe how you would measure the rate of reaction by pH change

A

See notes

31
Q

Describe how you would measure the rate of a reaction using a titration

A

See notes

32
Q

Describe the transition state theory

A

Molecules approach
Slow down due to electron could repulsion
Kinetic energy converted to potential energy
Insufficient kinetic energy then they’ll fly apart
Sufficient kinetic energy then they overcome repulsion and electrons are rearranged and product formed

33
Q

Describe the activated complex

A

Arranged at max PE
Reactant molecules partially broken
New bonds partially formed

34
Q

How do you determine the shape of a titration curve

A

See notes

35
Q

How do you make a buffer solution

A

See notes