Question

For each of the following determine whether the calculated molarity would be too low, too high, or unaffected and explain why? a. You added 1.0 zinc (instead of 0.3-0.4g) to your unknown. b. You added 50 ml DI (instead of 25mL) to your 10.00 mL unknown sample and then added the Zn c. the cooper was not completely dry before weighing

Answer 1

Ans .

As Molarity =( mass of solute in g/molar Mass of solute in g/mol)*(1000/volume of solution in ml )

a) when we added 1.0g of Zinc instead of 0.3-0.4g to the unknown , then the mass of solute is increased . As Mass of solute is directly proportional to Molarity , so , calculated Molarity would be too high .

b) When we add 50 ml of DI instead of 25 ml to our 10 ml unknown sample and then added Zinc , so , the volume of solution is increased .As volume of solution is inversely proportional to Molarity . So , calculated Molarity would be too low .

c) If the copper was not completely dry before weighing , then , water molecules also get attached with copper due to which the mass of solute can be higher than actual value . As Mass of solute is directly proportional to the Molarity . So, calculated Molarity would be too high .