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 Right arrow. 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

Answer:

107.9g

Explanation:

Given parameters:

Molar mass of Cu  = 63.5g/mol

Molar mass of Ag  = 107.9g/mol

Mass of reacting Cu  = 31.75g

Unknown:

Mass of Ag produced  = ?

Solution:

The reaction equation is given as;

    Cu + 2AgNO₃ →  Cu(NO₃)₂ + 2Ag

The equation is balanced.

We start by find the number of moles of the known;

  Number of moles  = $\frac{mass}{molar mass}$  

  Number of moles of Cu  = $\frac{31.75}{63.5}$   = 0.5moles

From the balanced equation;

       1 mole of Cu produced 2 moles of Ag;

      0.5 mole of cu will produce 0.5 x 2 mole of Ag  = 1 mole of Ag

Now;

 Mass of Ag  = number of moles x molar mass

 Mass of Ag  = 1 mole of Ag x 107.9g/mol  = 107.9g