Question

When copper is mixed with silver nitrate, the products of the reaction are copper(II) nitrate and solid silver.

If you start with a copper penny with a mass of 3.05 g and 208 mL of 0.100 M silver nitrate, determine the limiting reagent

Answer 1

The balanced equation is:

Cu + 2AgNO₃ --> Cu(NO₃)₂ + 2Ag

To determine the limiting reactant, there should be an amount of each reactant calculated (in moles):

$n(Cu)=\frac{3.05g}{63.55g/mol}=0.0480mol$

$n(AgNO_3)=0.208L\times0.100M=0.0208 mol$

According to the equation, the Cu : AgNO₃ molar ratio is 1 : 2.

The actual ratio is 0.0480 : 0.0208, which is 2.3 : 1, hence Cu is in excess, and AgNO₃ is limiting.

Answer: AgNO₃