pH curves and indicators

Question 1

What is the equivalence point?

Answer 1

The point at which if you add a tiny amount of base, there is a sudden big change in pH

• This is the vertical line on the graph.

Question 2

For weak acid/ weak base titration what do you use?

Answer 2

A pH meter
- This is because colour change is gradual AND THERE is no sharp change in pH

so it is hard to see an exact end point.

Question 3

what is the colour change for methyl orange?

Answer 3

From low to high pH

colour change is RED TO YELLOW

approximate range is 3.1 - 4.4

Question 4

What is the colour change for phenolphthalein?

Answer 4

From low to high pH

colour change is colourless to pink

Approximate range is 8.3 - 10

Question 5

What indicator is used for strong acid and strong base?

Answer 5

Both indicators ( phenolphthalein or methyl orange)

Question 6

What indicator is used for strong acid/weak base?

Answer 6

methyl orange

Question 7

What indicator is used for a weak acid/ strong base?

Answer 7

Phenolphthalein

Question 8

What indicator is used for weak acid/ weak base

Answer 8

No indicator