Question

A completed reaction yields 38 moles of Ag from the equation below. How much Cu did the equation start with?

Cu + AgNO3 → Ag + Cu(NO3)2

Answer 1

`19 "mol Cu"`

Explanation:

Step 1: Write a balanced equation
`Cu + 2AgNO_3 → 2Ag + Cu(NO_3)_2`

Step 2: Stoichiometry
#38 cancel("mol Ag") * (1"mol Cu")/(2 cancel("mol Ag") #=

`19 "mol Cu"`

Here's the deal, since they said "how much" of Cu was used, and no specific unit was given, we report the answer in the unit of Ag