Question

Zinc reacts with iodine in a synthesis reaction. Using a balanced chemical equation for the reaction, determine the percent yield of a 129.0gram sample of zinc was used and 510.6 grams of product is recovered

Answer 1

81.9 % is the percent yield of reaction of zinc with iodine producing ZnI2.

Explanation:

Balanced chemical equation for the reaction:

Zn + I2 ⇒ ZnI2

Data given:

mass of sample zinc = 129 grams  

mass of ZnI2 formed = 510.6 grams (actual yield)

number of moles = $\frac{mass}{atomic mass of one mole}$

 number of moles of zinc = $\frac{129}{65.38}$

                                            = 1.97 moles

from stoichiometry

1 mole of Zn reacts to form 1 mole of ZnI2

1.97 moles of Zn will form 1.97 moles of ZnI2

atomic mass of ZnI2 = 319.22 grams/mole

mass of ZnI2 formed = 628.86 grams (theoretical yield)

% yield = $\frac{actual yield}{theoretical yield}$ x100     equation 1

from the reaction,

Putting the values in equation 1

% yield = $\frac{510.6}{628.86}$  x 100

             =  81.19 % is the % yield.