# 5.1.3 - Acids, Bases And Buffers Flashcards

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1
Q

What are acids?

A

Proton donors

2
Q

What are bases?

A

Proton acceptors

3
Q

What do H+ ions form in water?

A

Hydronium ions H3O+

4
Q

What is the conjugate base?

A

The species that has lost a proton.

5
Q

What is a conjugate acid?

A

Species that has gained a proton.

6
Q

What are monoprotic acids?

A

Have only 1 proton they can release into solution.

7
Q

Acid + alkali

A

Metal salt + Water

8
Q

Acid + base

A

Metal salt + Water

9
Q

Acid + carbonate

A

Metal salt + Water + Carbon dioxide

10
Q

Acid + Metal

A

Metal salt + hydrogen

11
Q

What is Ka used to calculate?

A

The concentration of a weak acid.

12
Q

The higher the Ka?

A

The stronger the acid.

13
Q

The lower the Ka?

A

The weaker the acid.

14
Q

Ka =

A

[H+]^2 / [HA]

15
Q

pKa =

A

-log Ka

16
Q

ph =

A

-log[H+]

17
Q

[H+] =

A

10^-pH

18
Q

Kw =

A

[H+] x [OH-]

19
Q

When a metal has a valency of 1 what does [OH-] =

A

[MOH]

20
Q

If you are using a metal with a valency of 2, e.g. calcium what do you need to do to the value of [MOH] to find [OH-]?

A

Times by 2

21
Q

What is a buffer?

A

A solution that as a system minimises pH changes on addition of small amounts of acid or base.

22
Q

What 2 ways are buffers made?

A
• weak acid with the salt of its conjugate base.

- mix of an excess weak acid with a strong alkali.

23
Q

In the buffer CH3COOH H+ + CH3COO- what happens when you increase H+ ?

A

The extra H+ ions combine with the CH3COO ions, causing the equilibrium to shift to the left reducing the concentration of H+.

24
Q

In the buffer CH3COOH H+ + CH3COO- what happens when you increase OH- ?

A

OH- ions react with the H+ ions forming water, removing H+ ions. This causes CH3COOH to dissociate to form H+ ions # shifting the equilibrium to the right.

25
Q

What does the pH in the blood need to be?

A

7.35 and 7.45

26
Q

What is the pH in the blood controlled by?

A

Carbonic acid-hydrogen carbonate buffer system.
H2CO3 H+ + HCO3-
H2CO3 H2O + CO

27
Q

How are levels of H2CO3 controlled in the body?

A

By respiration - by breathing out CO2 the level of H2CO3 is reduced as it moves this equilibrium to the right.

28
Q

How are the levels HCO3- controlled?

A

The kidneys - they excrete extra in the urine.

29
Q

How do you select an indicator for a titration?

A

The indicator just change colour over the narrow range that lies entirely on the vertical part of the pH curve.

30
Q

What is the colour change from acid to alkali for methyl orange?

A

Red to yellow

31
Q

What is the colour change from acid to alkali for phenolphthalein?

A

Colourless to pink.

32
Q

What can indicators be though of as?

A

Weak acids as they have conjugate pairs.