Standard solutions and dilutions

Question 1

A solution of accurately known concentration is called a?

Answer 1

Standard solution

Question 2

How can standard solutions be prepared?

Answer 2

By accurate dilution by pipetting an appropriate volume of a standard solution into a volumetric flask, making up to the graduation mark with solvent, stoppering and inverting

Question 3

A primary standard must?

Answer 3

Be available in a high state of purity, be stable when solid and in solution and have a reasonable high GFM

Question 4

Give an example of a primary standard

Answer 4

Sodium carbonate, hydrated oxalic acid, potassium hydrogen phthalate, silver nitrate, potassium iodate and potassium dichromate

Question 5

If sodium hydroxide is being used in volumetric analysis what needs to be done to it first? Why is this?

Answer 5

It must be standardised. It is not a primary standard as it has a low GFM, is unstable as a solid (absorbs moisture) and unstable as a solution.