21 Flashcards Preview

A Level Chemistry > 21 > Flashcards

Flashcards in 21 Deck (6):
1

What is a buffer solution?

A system that minimises pH changes on addition of small amounts of an acid or base

2

Types of buffers

Acidic buffer: weak acid + salt
Basic buffer: weak base + salt
OR Weak acid + strong alkali

3

Acid-base pairs, controlling pH

Conjugate base removes added acid (left)
Weak acid removes added alkali (right)

4

pH of a buffer solution

[H+] = Ka x [HA]/[A-]

5

Controlling blood pH (H2CO3 + HCO3-)

H2CO3 → H+ + HCO3-
Blood plasma = 7.35-7.45

6

pH titration curves - indicators

Equivalence point = centre of vertical line
Phenolphthalein = strong base ( colourless → pink)
Methyl orange = strong acid (red → yellow)