Solution Stoichiometry

1
Solution Stoichiometry

• Edward A. Mottel
• Department of Chemistry
• Rose-Hulman Institute of Technology

2
Concentration Units

• Reading Assignment
• Zumdahl Chapter 4.1-4.3, 5
• Solutions can be described by several different
  concentration units.
• Density ( r )
• Mole Fraction (c)
• Molality (m)
• Molarity (M)
• Parts per Million (ppm)

3
Applications

• Density (mass per volume)
• rough measure of concentration
• battery acid
• anti-freeze
• Mole Fraction (moles / total moles)
• colligative property measurements
• gas mixtures, vapor pressure, distillation

4
Applications

• Molality (moles of solute / kilogram of solvent)
• colligative property measurements
• change in freezing point, boiling point
• vapor pressure, osmotic pressure
• Molarity (moles of solute / liter of solution)
• bench top laboratory applications
• titration

5
Applications

• Analytical applications
• Parts per Million (ppm)
• trace analysis, impurities
• Parts per Billion (ppb)
• environmental
• Parts per Trillion (ppt)

6
Preparation of Solutions

• From pure compounds
• By the mixture of a solid and a solution
• By the mixture of two solutions
• Note
• masses are always additive
• volumes involving concentrated solutions may not
  be additive

7
Solution Preparation

• Prepare 500. mL of 3.0 M sulfuric acid from
  sulfur trioxide gas and water.
• Outline the process
• Solve the problem

8
Prepare 500. mL of 3.0 M sulfuric acid from
sulfur trioxide gas and water.
9
Prepare 500. mL of 3.0 M sulfuric acid from
sulfur trioxide gas and water.

• Dissolve 120. grams of sulfur trioxide in enough
  water to give 500. mL of solution.

10
Solution Preparation

• Prepare 275 mL of 0.450 M aqueous sulfuric acid
  solution from 18.0 M sulfuric acid and water.
• Outline the process
• Solve the problem

11
Prepare 275 mL of 0.450 M aqueous sulfuric acid
solution from 18.0 M sulfuric acid and water.
Write a balanced equation
Define terms
12
Prepare 275 mL of 0.450 M aqueous sulfuric acid
solution from 18.0 M sulfuric acid and water.
Dissolve 6.87 mL of 18.0 M sulfuric acid in some
water and then dilute to 275 mL of total
solution volume.
13
Solution Preparation

• Prepare 400. mL of 2.50 M sulfuric acid from 1.00
  M sulfuric acid and 6.00 M sulfuric acid. Assume
  volumes are additive.
• Outline the process
• Solve the problem

14
Prepare 400. mL of 2.50 M sulfuric acid from
1.00 M sulfuric acid and 6.00 M sulfuric acid.
Write a balanced equation
Define terms
15
Prepare 400. mL of 2.50 M sulfuric acid from
1.00 M sulfuric acid and 6.00 M sulfuric acid.
Volumes of reactants needed
Write a balanced equation
What information would be needed if this
isnt assumed?
Define terms
16
Prepare 400. mL of 2.50 M sulfuric acid from
1.00 M sulfuric acid and 6.00 M sulfuric acid.
x mL of 1.00 M H2SO4
y mL of 6.00 M H2SO4
x y 400 mL
(x 1.00 M) (y 6.00 M) 400 mL 2.50 M
y 120. mL
17
Neutralization

• Balanced Equation
• Moles react with moles

moles of acid moles of base
18
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