The Foundations of Chemistry

We convert (1) grams of Na 2 CO 3 to moles of Na 2 CO 3 , (2) moles of Na 2 CO 3 to moles of
H 2 SO 4 , and (3) moles of H 2 SO 4 to liters of H 2 SO 4 solution.

g Na 2 CO 3 88n mol Na 2 CO 3 88n mol H 2 SO 4 88n L H 2 SO 4 soln

Solution

__?L H 2 SO 4 2.792 g Na 2 CO 3 

 0.0813 L H 2 SO 4 soln or 81.3 mL H 2 SO 4 soln

You should now work Exercise 76.

Often we must calculate the volume of solution of known molarity that is required to
react with a specified volume of another solution. We always examine the balanced chem-
ical equation for the reaction to determine the reaction ratio,that is, the relative numbers
of moles of reactants.

EXAMPLE 3-23 Volume of Solution Required

Find the volume in liters and in milliliters of a 0.505 MNaOH solution required to react with
40.0 mL of 0.505 MH 2 SO 4 solution according to the reaction

H 2 SO 4 
2NaOH88nNa 2 SO 4 
2H 2 O

Plan

We shall work this example in several steps, stating the “plan,” or reasoning, just before each
step in the calculation. Then we shall use a single setup to solve the problem.

1 L H 2 SO 4 soln



0.324 mol H 2 SO 4

1 mol H 2 SO 4



1 mol Na 2 CO 3

1 mol Na 2 CO 3



106.0 g Na 2 CO 3

The indicator methyl orange

changes from yellow, its color in ba-

sic solutions, to orange, its color in

acidic solutions, when the reaction

in Example 3-22 reaches completion.

3-8 Using Solutions in Chemical Reactions 111