Titrations

Question 1

When do we use phenolphthalein?

Answer 1

Strong bases

Question 2

When do we use methyl orange

Answer 2

Strong acids

Question 3

When we use methyl orange, what is the colour change when adding acid to alkali?

Answer 3

Yellow to red

Question 4

When we use methyl orange, what is the colour change when adding alkali to acid?

Answer 4

Red to yellow

Question 5

When we use phenolphthalein, what’s the colour change when we add acid to alkali?

Answer 5

Pink to colourless

Question 6

When we use phenolphthalein, what’s the colour change when we add alkali to acid?

Answer 6

Colourless to pink

Question 7

What indicator is used for I2 with S2O3 2-?
Describe the colour changes of the thiosulfate solution?

Answer 7

Indicator = starch
Colour changes:
Yellow, then add starch
Blue-black to colourless at endpoint.

Question 8

What indicator is required for Fe2+ with MnO4 -?
Why is this?
What is the colour change?

Answer 8

NO INDICATOR REQUIRED
Acidified solution changes from colourless to pink.