Stoichiometry of Solutions

Most reactions occur in aqueous solutions because water is cheap, easily accessible and dissolves many substances

Chemicals mix more completely when they are dissolved resulting in faster reactions

Allows you to adjust concentrations and temperature for optimal results

Why solutions?

Solution stoichiometry – the procedure for calculating the molar concentration or volume of solution products or reactants

Stoichiometry and Reactions

Solution stoichiometry steps

Concentration and volume of given substance

Amount of given substance

Amount of required substance

Quantity of required substance withknown concentration or volume

Molar ratio comparison

𝒏=𝑪𝑽

𝑪=𝒏𝑽

Ammonia and phosphoric acid solutions are used to produce ammonium hydrogen phosphate fertilizer. What volume of 14.8mol/L NH3(aq) is needed to react with 1.00kL of 12.9mol/L of H3PO4(aq)?

2NH3(aq) + H3PO4(aq) (NH4)2HPO4(aq)

V = ? V = 1.00kL

14.8mol/L 12.9 mol/L

Example 1

In an experiment, a 10.00 mL sample of sulfuric acid solution reacts completely with 15.9 mL of 0.150 mol/L potassium hydroxide. Calculate the amount concentration of the sulfuric acid.

H2SO4(aq) + 2KOH(aq) 2H2O(l) + K2SO4(aq)

V = 10.00mL V = 15.9 mL

c = ? 0.150 mol/L

Example 2

A technician dissolves 17.1g of Aluminum Sulfate, Al2(SO4)3 to make 250.0mL of solution. What are the amount concentrations of aluminum and sulfate ions?

Example 3

1. Write a balanced chemical equation and list the quantities and conversion factors for the given substance and the one to be calculated.

2. Convert the given measurement to its chemical amount (in moles) using the appropriate conversion factor

3. Calculate the amount of the other substance using the mole ratio from the balanced chemical equation.

4. Convert the calculated chemical amount to the final quantity requested using the appropriate conversion factor.

Solution Stoichiometry Summary

Stoichiometry Calculations

(Measured quantity)

solids/liquids m n

solutions c, V

solutions c, Vsolids/liquids m

n

(Required quantity)

Pg 449 # 1-9

Homework