Question

Consider the case in which the bottle of ferric nitrate contained moisture. Will the reported concentration of iron in the unknown sample be higher, lower, or the same as the actual concentration of iron in the sample.

Answer 1

Ferric nitrate contained moisture​. So, the actual ferric nitrate will be ferric nitrate and water.

Now, mass taken for ferric nitrate will be the mass of both ferric nitrate and water. Hence the actual mass of ferric nitrate will be less.

Moles = Mass / Molar mass

Since, the mass (numerator) is less, so the moles will be also less (since molar mass is a constant term).

Concentration = Moles / Volume

Now, Moles is less (numerator) so, the concentration will also be less for the fixed volume.

So, answer is the reported concentration of iron in the unknown sample will be lower as the actual concentration of iron in the sample.