Question

Zinc, Zn, adn iodine, I2, react to form zinc(II) iodide, ZnI2 ( the reactants and the product are all solids at room temperature).

a. write a balanced chemical reaction for this process.

b. suppose that 50.0 g of zinc and 50.0 g of iodine are used to form zinc(II) iodide.

1. assuming that the reaction goes to completion, which element will be totally consumed in the formation of the zinc(II) iodide?

2. what is the limiting reagent?

3. how many grams of zing(II) iodide can be produced?

4. how many grams of the excess element remain unreacted?

Answer 1

a. Zn + I2 --------> ZnI2

b. no of moles of Zn = W/G.A.Wt

                                   = 50/65.4 = 0.765 moles

no of moles of I2 = W/G.M.Wt

                                = 50/254 = 0.197 moles

c. 1 mole of Zn react with 1 mole of I2

    0.765 moles of Zn react with 0.76 moles of I2

I2 is limiting reagent. It is completely consumed in the reaction.

d. 1 mole of I2 react with Zn to gives 1 mole of ZnI2

      0.197 moles of I2 react with Zn to gives = 1*0.197/1 = 0.197 moles of ZnI2

   mass of ZnI2 = no of moles * gram molar mass

                           = 0.197*319.4 = 62.92g of ZnI2

4. Remaining excess reagent = 0.76-0.197   = 0.563 moles of excess reagent

unreactant mass of excess reagent         = 0.563*65.4 = 36.82 g