Acids, Bases & Buffers 5.1.3

Question 1

What is a Brønsted-Lowry Acid?

Answer 1

A proton donor

Question 2

What is a Brønsted-Lowry Base?

Answer 2

A proton acceptor

Question 3

How are Brønsted-Lowry Acids and Bases related?

Answer 3

Acid ⇌ Proton + Conjugate Base

Base + Proton ⇌ Conjugate Acid

Question 4

What is meant by Monobasic and Dibasic Acids?

Answer 4

Monobasic:
Have only one replaceable H
Dibasic:
Have two replaceable H’s

Question 5

What links pH and H+ concentrations?

Answer 5

pH = -log[H+]
[H+] = 10^(-pH)

Question 6

Is pH Linear or Logarithmic?

Answer 6

Logarithmic

eg. pH of 5 is 10 times stronger than 6. and 100 time stronger than 7

Question 7

What is the equation for the [H+] of a weak Acid?

Answer 7

[H] = ([HA}Ka)^0.5

Question 8

What is [HA], [A-] and [H+]?

Answer 8

[H+]:
Concentration of hydrogen
[A-]:
Concentration of conjugate base
[HA]:
Concentration of Acid

Question 9

What is Ka?

Answer 9

Dissociation constant

Can vary by several orders of magnitude

Question 10

What is PKa?

Answer 10

Simplified version of Ka so that it doesn’t vary by several orders of magnitude

Question 11

What links PKa and Ka?

Answer 11

PKa = -Log(Ka)
Ka = 10^(-Pka)

Question 12

What is the equation for the Ionic Product of Water?

Answer 12

Kw = [H+] x [OH-]

Question 13

What is numericly is Kw

Answer 13

1.0 x 10^-14 mol^2 dm^-6

At RTP

Question 14

What is the Ionic Product of Water used for?

Answer 14

Calculating the pH of a strong base

Question 15

Name 3 indicators?

Answer 15

Methyl-Orange
Litmus
Phenolphthalein

Question 16

What is the Point of Equivalance?

Answer 16

The vertical section of a pH curve

Question 17

What does Sharp and Shallow changes of gradient mean on a pH curve

Answer 17

Sharp:
Strong Acid or Base
Shallow:
Weak Acid or Base`

Question 18

Define Buffer Solutions?

Answer 18

Solutions which resist the change of pH when small quantites of acid or alkali are added

Question 19

What are uses of Buffer Solutions?

Answer 19

Standarising pH meters
Maintaing the pH of substances such as Shampoo, washing powder and lemonade
Biological Buffers maintain pH of things such as blood

Question 20

What happens in H+ is added to a Buffer Solution?

Answer 20

The conjugate base in the buffer will react with the H+.

And the weak acid will dissociate to maintain the pH

Question 21

What happens if OH- is added to a Buffer Solution?

Answer 21

The H+ in the buffer will react with the OH-

And weak acid will dissociate to maintain pH

Question 22

Whjat is an example of a Biological Buffer?

Answer 22

Carbonic Acid ⇌ Proton + Hydrogen Carbonate

H2CO3 ⇌ H + HCO3

Question 23

How does Carbonic Acid maintain the pH of Blood?

Answer 23

H+ excess:
H+ reacts with HCO3- to form H2CO3. Which the decomposes to H2O and CO2.
Which are removed in breath and urine
OH- excess:
OH- reacts with H+ to form H2O.
Which is removed in urine.

Question 24

What is the Enthalpy of Neutralisation?

Answer 24

The energy change when a sufficient amount of acid or alkali is neutralised to produce one mole of water.
Is always close to -57kJ/mole