U4-4-1 - Standard Solutions and Primary Standards

Question 1

Standard solution

Answer 1

A solution of accurately known concentration.

Question 2

Name this piece of equipment

Answer 2

Pipette

Question 3

Name this piece of equipment

Answer 3

Burette

Question 4

Name this piece of equipment

Answer 4

Volumetric/standard flask

Question 5

Which 4 phrases must be included in the procedure for preparing a standard solution from a solid?

Answer 5

Deionised/distilled water

Transfer with rinsings

Volumetric/standard flask

Fill up to the mark

Question 6

Describe the procedure to prepare a standard solution from a stock solution.

Answer 6

Pipette required volume of stock solution into a volumetric flask.

Make up to the mark with deionised water.

Question 7

Accurately approximately

Answer 7

Exact value should be known (e.g. accurate balance reading), and needs to be close to target value.

Question 8

Primary standard

Answer 8

A substance that can be used to standardise a solution.

OR

Substance which can be used to prepare a standard solution (without needing to be standardised).

Question 9

Characteristics of primary standards (state 2)

Answer 9

Any 2 of:

available in high state of purity

stable in air and in solution

soluble

reasonably high GFM.

Question 10

Why is NaOH not a primary standard?

Answer 10

Low GFM, hygroscopic (absorbs water), unstable in solution

Question 11

What must be done to a non-primary standard solution before it can be used in titration?

Answer 11

Must be standardised by titrating against a known accurate mass/concentration of a primary standard.

Question 12

Give an example of a primary standard.

Answer 12

Any one of:

sodium carbonate

oxalic acid

potassium hydrogen phthalate

silver nitrate

potassium iodate

potassium dichromate.