Question

Copper metal (Cu) reacts with silver nitrate (AgNO3) in aqueous solution to form Ag and Cu(NO3)2. An excess of AgNO3 is present. The balanced chemical equation is shown below.
Cu + 2AgNO3 ---> Cu(NO3)2 + 2Ag

The molar mass of Cu is 63.5 g/mol. The molar mass of Ag is 107.9 g/mol. What mass, in grams, of Ag is produced from reaction of 31.75 g of Cu?

26.95
107.9
215.91
431.82

Answer 1

we are given the reaction Cu + 2AgNO3 ---> Cu(NO3)2 + 2Ag. This means for every mole Cu used, there are 2 moles of Ag produced. In this case, given 31.75 g Cu, converting to moles through molar mass and using stoichiometric ratio and the molar mass of Ag, the mass Ag produced is 107.9 grams. 

Answer 2

The mass in grams of Ag produced from reaction of 31.75g of Cu is 107.9 grams

calculation

Cu+2AgNO3 ---> Cu(NO3)2 + 2Ag

find the moles of Cu that reacted

moles= mass/molar mass

=31.75 g/63.5 g/mol= 0.5 moles

from the equation above the mole ratio of CU:Ag is 1:2 therefore the moles of Ag=0.5 moles x2 = 1 mole

mass of Ag= moles of Ag x molar mass

= 1 mole x107.9g/mol = 107.9 grams