Question

1. A copper bar with a mass of 10.650 g is dipped into 216 mL of 0.106 M AgNO₃ solution. When the reaction that occurs has finally ceased, what will be the mass of the unreacted copper in the bar?

2. If all the silver that forms adheres to the copper bar, what will be the total mass of the bar after the reaction?

Answer 1

1. A copper bar with a mass of 10.650 g is dipped into 216 mL of 0.106 M AgNO3 solution. When the reaction that occurs has finally ceased, what will be the mass of the unreacted copper in the bar?

Solution:

Cu + 2AgNO₃ -----> Cu(NO₃)₂ + 2Ag

mole Cu = (10.650g)/(63.546g/mol) = 0.1676 mol

mole AgNO₃ = (0.106mol/L AgNO₃)(0.216L AgNO₃) = 0.0229 mol

Cu needed to react all AgNO₃ = (0.0229)(2) = 0.0458 mol

unreacted Cu = 0.1676 - 0.0458 = 0.1218 mol

mass of Cu = 0.1218mol*63.546g/mol = 7.74g

2. If all the silver that forms adheres to the copper bar, what will be the total mass of the bar after the reaction?

AgNO₃ reacted to Ag = 0.0229mol

MW of Ag = 107.8682g/mol

mass Ag = (0.0229 mol)(107.8682g/mol) =2.47g

total mass = 2.47g + 7.74g = 10.21g