# Question #1dc6a

Jun 25, 2016

You will have to add 187.1 mg of copper.

#### Explanation:

$\text{Cu" + "2AgNO"_3 → "Cu"("NO"_3)_2 + 2"Ag}$

Mass of Cu

${\text{Moles of AgNO"_3 = 1.000 color(red)(cancel(color(black)("g AgNO"_3))) × ("1 mol AgNO"_3)/(169.87 color(red)(cancel(color(black)("g AgNO"_3)))) = "0.005 887 mol AgNO}}_{3}$

$\text{Moles of Cu" = "0.005 887" color(red)(cancel(color(black)("mol AgNO"_3))) × (1 "mol Cu")/(2 color(red)(cancel(color(black)("mol AgNO"_3)))) = "0.002 943 mol Cu}$

$\text{Mass of Cu" = "0.002 943" color(red)(cancel(color(black)("mol Cu"))) × ("63.55 g Cu")/(1 color(red)(cancel(color(black)("mol Cu")))) = "0.1871 g Cu" = "187.1 mg Cu}$

Mass of 999 Ag

$\text{Moles of Ag" = "0.005 887" color(red)(cancel(color(black)("mol AgNO"_3))) × "2 mol Ag"/(2 color(red)(cancel(color(black)("mol AgNO"_3)))) = "0.005 887 mol Ag}$

$\text{Mass of Ag" = "0.005 887" color(red)(cancel(color(black)("mol Ag"))) × "107.9 g Ag "/(1 color(red)(cancel(color(black)("mol Ag")))) = "0.6352 g Ag" = "635.2 mg Ag}$

$\text{Mass of 999 Ag" = 635.2 color(red)(cancel(color(black)("mg Ag"))) × "1000 mg 999 Ag"/(999 color(red)(cancel(color(black)("mg Ag")))) = "635.8 mg 999 Ag}$

You will need to add 187.1 mg of $\text{Cu}$, and you will get 635.8 mg of 999 $\text{Ag}$.