Stoichiometry

Question 0

To convert moles to mass what relationship should be used?

Answer 0

1 mole = 1 gfm

Question 1

What is a quantitative reaction?

Answer 1

Any reaction in which the substances react completely according to the mole ratios given by a balanced (stoichiometric) eqn.

Question 2

What relationship should be used when working with volumes of gases?

Answer 2

1 mole of gas occupies 1 molar volume

Question 3

What happens to the number of moles of solute when diluting a concentrated sol? And what eqn can we use for calculations?

Answer 3

Nothing, remains unchanged, only the amount of solvent changes.
M1V1 = M2V2

Question 4

What is a standard solution?

Answer 4

A solution of accurately known concentration

Question 5

What characteristics does a primary standard have? And why does it have these characteristics?

Answer 5

1) must be readily available in a high state of purity (>99%)
2) should be stable in air at normal temps, so that it can be stored indefinitely without change in composition
3) should be readily soluble (usually in water), and the sol should be stable
4)should have a reasonably high FM so that the errors in weighing molar quantities are reduced.
These are required to ensure what is weighed out is an uncontaminated, accurate amount of the material. The most important property = the stability

Question 6

E.g’s of primary standards?

Answer 6

Oxalic acid/ anhydrous sodium carbonate for acid/base titrations
EDTA for complexometric titrations
Potassium iodate/ oxalic acid for redox titrations

Question 7

What is the equivalence point?

Answer 7

When the reaction is just complete

Question 8

What is complexometric volumetric analysis used for?

Answer 8

Estimating metal ions in solution by using their ability to form complex ions with certain organic ligands