A 300.0 mL volume of a 0.10 M stock solution of Cu+2 is to be prepared using CuS

Question

A 300.0 mL volume of a 0.10 M stock solution of Cu+2 is to be prepared using CuSO4. 5H2O (molar mass = 249.68 g/mol).
(a) How many grams of CuSO4. 5H2O must be measured for the preparation?
(b) Describe the PROCEDURE for the preparation of the solution using 0.1 M HNO3 as a diluent.
(c) A 5.00 mL pipet transfers the Cu+2 stock solution to a 100.0 mL volumetric flask that is then diluted “to the mark” of the volumetric flask with 0.1 M HNO3 . What is the molar concentration of the diluted Cu+2 solution?

Explanation / Answer

a) the volume of solution = 300mL

concentration of stock solution = 0.1 M

molarity = Mass of solute / Molecular weight of solute X volume of solution in litres

0.1 = Mass / 249.68 X 0.3

Mass of copper sulphate used for preparation = 0.1 X 249.68 x 0.3 = 7.49 grams

b) We will weight 7.49 grams of copper sulphate using electronic balance.

Will take the salt in a volumetric flask of 300mL

We will add 300mL of HNO3 to it to get the desired solution

c) Iniital concentration = 0.1 Molar

Initial volume taken = 5mL

Final concentration = ?

Final volume = 100mL

Equating the moles

Initial volume X initial concentration = final volume X final concentration

Final concentration = 5 X 0.1 / 100= 0.005 Molar

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