Solution Stoichiometry

Solution Stoichiometry calculations
involve chemical reactions that take place
in solution.

Balanced Chemical reactions are written in
terms of moles of reactants and products.

Molarity relates moles of solute to volume of
solutions. Thus, a measured volume of a
solution provides a simple method of measuring
the moles of reactants.

*We use molarity and volume to convert to moles
instead of mass and molar mass.
Example: How many moles are in 15mls of
0.76M KCl?
 15mls
1L
0.76 moles
1000mls
1 liter

= 0.011 moles KCl

Solution stoichiometry will give you volumes of solutions
of reactants and ask how many grams of a precipitate
will form.
Example: Silver nitrate is added to 25.0 mls of a 0.50M
KCl solution until no more precipitate forms. What mass
of AgCl will be formed?
Step 1 – Write the balanced chemical reaction.
AgNO3(aq) + KCl(aq)  AgCl(s) + KNO3(aq)

Step 2 – Set up dimensional analysis solution.



25.0mls
1L
1000ml
0.50mols
KCl
1 mol AgCl
143.35g
1L
1mol KCl
1 mol AgCl
= 1.79 grams AgCl should form.

It can also allow you to determine what volume of
a reactant is needed to react away a given volume
of another reactant.

Example - What volume of 0.50M KCl is required to react
away all the silver ions in 45mls of 0.35M AgNO3?

AgNO3(aq) + KCl(aq)  AgCl(s) + KNO3(aq)
45mls
AgNO3
1L
1000mls
0.0315 Liters
0.35mol
AgNO3
1L
1mol
KCl
1 L KCl
1mol
AgNO3
0.5mols
KCl
= 31.5 mls of 0.50M KCl is required