Volumetric Analysis

Question 1

What is a standard solution?

Answer 1

Solution of accurately known concentration

Question 2

What can a standard solution be prepared from?

Answer 2

a primary standard

Question 3

What characteristics must a primary standard have?

Answer 3

A primary standard must have, at least, the following characteristics: 
 high state of purity  
stability in air and in solution   
solubility  
reasonably high formula mass

Question 4

Give 3 examples of primary standards.

Answer 4

sodium carbonate, Na2CO3 
oxalic acid, H2C2O4.2H2O  
potassium dichromate, K2Cr2O7

Question 5

Describe the purpose of a control.

Answer 5

A control validates a technique and may consist of carrying out a determination on a solution of known concentration.

Question 6

What are complexometric titrations based on?

Answer 6

Complexometric titrations are based on reactions in which complexes are formed.

Question 7

Describe what a back titration is?

Answer 7

Back titration is used to find the number of moles of a substance by reacting it with an excess volume of reactant of known concentration. The resulting mixture is then titrated to work out the number of moles of the reactant in excess. From the initial number of moles of that reactant the number of moles used in the reaction can be determined, making it possible to work back to calculate the initial number of moles of the substance under test

Question 8

What is a back titration useful for?

Answer 8

. A back titration is useful when trying to work out the quantity of substance in a solid with a low solubility.