Answer:
88 %
Explanation:
This is question we can solve by using the stoichiometry for the balanced chemical equation:
Cu + 2 AgNO₃ ⇒ Cu(NO₃)₂ + 2 Ag
Given the mass of copper we can calculate how many moles it represents, and from the stoichiometry of the reaction we know 1 mol Cu produces 2 moles Ag, so we can calculate the moles Ag that theoretically should have been produced.
Finally we can determine the number of moles of Ag actually produced and calculate the percent yield.
We will need the atomic weights of Cu and Ag (63.54 g/mol, 107.87 g/mol respectively).
# mol Cu = 12.7 g x 1mol/63.54 g/mol = 0.20 mol
# mol theoretical Ag produced = (2 mol Ag/ 1 mol Cu) x 0.20 mol Cu
= 0.40 mol Ag theoretical
# mol Ag actually produced = 38.1 g Ag / 107.87 g/mol = 0.35 mol
The percent yield is then:
= (0.35 / 0.40) x 100 = 88 %
