Acid- Base Titrations

Question 1

What steps should be taken to ensure accuracy?

Answer 1

• rinse the apparatus with the appropriate solution
• add the solution from the burette dropwise just before the endpoint
• swirl the flask
• read the burette at the bottom of the meniscus

Question 2

What are the steps in carrying out a titration?

Answer 2

• rinse the pipette with the solution to be transferred to the conical flask
• using a pipette and pipette filler place (25.0 cm3) of the solution in the conical flask
• rinse the burette with the solution to be placed in it
• fill the burette with this solution and record the reading on the burette to one or two decimal
  places; the second decimal place should be a zero or a five
• Add 3-5 drops of a suitable indicator to the conical flask
• Add the solution from the burette, with swirling, until the indicator just changes colour
• Record the reading to one or two decimal places reading to the bottom of the meniscus (the
  second decimal place should be 0 or 5)
• Repeat the titration to achieve 2 concordant results. (within 0.2(0) cm3 of each other)

Question 3

How to prepare solution of a known concentration?

Answer 3

• calculate the required mass of the solid/liquid required to make the solution (or the required
  volume of liquid)
• weigh the solid/liquid in a beaker on a top pan balance (or measure the volume of the liquid using
  a graduated pipette/burette/measuring cylinder, as appropriate)
• dissolve the solid in a small volume (50–100 cm3) of deionised water
• transfer the solution to the appropriately sized volumetric flask
• rinse the beaker and glass rod with deionised water and add washings to the volumetric flask
• make up to the mark by adding deionised water until the bottom of the meniscus is on the mark
• stopper the flask and invert to mix

Question 4

What is a strong acid?

Answer 4

Fully ionised in water

Question 5

What is a weak acid?

Answer 5

Partially ionised in water

Question 6

What colour is ph in acid?

Answer 6

Colourless

Question 7

What colour is ph in neutral?

Answer 7

Colourless

Question 8

What colour is ph in alkali?

Answer 8

Pink

Question 9

What is titr of ph suitable for?

Answer 9

Strong acid/ base
Weak acid, strong base

Question 10

What colour is methyl orange in acid?

Answer 10

Red

Question 11

What colour is methyl orange in neutral?

Answer 11

Orange

Question 12

What colour is methyl orange in alkali?

Answer 12

Yellow

Question 13

What is titr is methyl orange suitable for?

Answer 13

Strong acid/base
Strong acid-weak base

Question 14

For ph. what is colour change when there is an acid in the conical flask and an alkali in burette?

Answer 14

Colourless to Pink

Question 15

For M.O what is the colour change when there is an acid in the conical flask and an alkali in the burette?

Answer 15

Red to Yellow

Question 16

For ph. what is the colour change when there is an alkali in the conical flask and an acid in the burette?

Answer 16

Pink to Colourless

Question 17

For Methyl Orange what is the colour change when there is an alkali in the conical flask and an acid in the burette?

Answer 17

Yellow to Red