12.1. Mole Ratios http://www.ck12.org
Therefore, we would also need 0.5 mol of sodium chloride in order to produce 0.5 mol of silver chloride. Notice
that in each case, we use the mole ratio to relate moles of reactants to moles of products.
Not all reactions have 1:1 ratios between reactants and products. For instance, the reaction between lead(II) nitrate
and sodium chloride produces the precipitate lead(II) chloride and aqueous sodium nitrate:
Pb(NO 3 ) 2 (aq)+ 2NaCl(aq)→PbCl 2 (s)+ 2 NaNO 3 (aq)
FIGURE 12.1
Lead(II) chloride is commonly used in
the production of decorative glass, called
aurene. It also has many other uses.
For example, it is used in the production
of paints and in industrial processes that
remove unwanted metals.Example 12.2
If we wanted to make 0.5 mol of lead(II) chloride, how many moles of each reactant would be needed?
Answer:
First, we will relate moles of the reactant sodium chloride to the desired product. The mole ratio between these two
substances can be used as a conversion factor as follows:
0.5 mol PbCl 2 ×( 12 mol PbClmol NaCl
2
) = 1 mol NaCl
In order to produce 0.5 mol of lead(II) chloride, we would need 1 mol of sodium chloride. The necessary amount of
the other reactant can be calculated in the same way:
0.5 mol PbCl 2 ×(^1 mol Pb 1 mol PbCl(NO 23 )^2 ) = 0.5 mol Pb(NO 3 ) 2
We can use mole ratios to determine the amounts of reactants needed to produce a given amount of product. As we
will see in the next lesson, we can also convert these amounts into masses using our understanding of molar mass.