Name: Section:- Stoichiometry:A Mole Rano smdy Date: Post-Lab Questions How woul

Question

Name: Section:- Stoichiometry:A Mole Rano smdy Date: Post-Lab Questions How would each of the following modifications to the experimental procedure used in this investigation affect the mass of product obtained? Indicate if the mass of product would be greater, less, or unchanged. Explain your reasoning 1. (a) The KI solution is added to the Pb(NO;): solution instead of adding the Pb(NO;h solution to the KI solution. (Note: Pblz is slightly soluble in water) (b) The temperature of the reactant solutions is 40 °C instead of room temperature. (c) The residue is washed with hot distilled water instead of cold distilled water (d) The residue is not washed with distilled water at all. (e) The reactions were performed using 6.00 ml. of 2.00 M KI instead of 6.00 mL of 1.00 M KI. 78

Explanation / Answer

a)

No effect if you ensure it is well mixed

there will be effect if some solid forms or oyu do not allow solids to form totally

b)

This increases solubility of PbI

which allow LESS solid to form,

meaning that your solubility will be higher

therefore

Ksp increases since it is directly proportional to solubility

c)

similar as in b

d)

if you do not wash it; then you will not have all the TOTAL mass of PbI2

therefore, the mass of PbI2 measured decreases

meaning that solubility increases

and Ksp increases as wel

e)

this depends on the limiting reactant

if Pb+2 is limiting reaction, then there is no effect

if I- i slimiting reaction, then your total clacualtion will be incorrect, since it is based on moles of I- used

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