1. Types of solution stoichiometry problems
Dilutions
Gravimetric analysis
Titrations
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2. Gravimetric Analysis
Determining % (by mass) of an element in an unknown ionic compound
Dissolve unknown substance in water
React unknown with known substance to form a precipitate
Filter and dry precipitate
Weigh precipitate
Use chemical formula and mass of precipitate to determine amount of unknown ion
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3. Example 4.7)
A g sample of an ionic compound containing chloride ions and an unknown metal is dissolved in water and treated with an excess of AgNO3. If g of AgCl precipitate forms, what is the percent by mass of Cl in the original compound?
47.51%
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4. 4.71)
If 30.0 mL of M CaCl2 is added to 15.0 mL of M AgNO3, what is the mass in grams of AgCl precipitate?
0.215 g AgCl
…now try 4.73!
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5. Equivalence point – the point at which the reaction is complete
Titrations
In a titration a solution of accurately known concentration is added gradually added to another solution of unknown concentration until the chemical reaction between the two solutions is complete.
Equivalence point – the point at which the reaction is complete
Indicator – substance that changes color at (or near) the
equivalence point
Slowly add base
to unknown acid
UNTIL
the indicator
changes color
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6. What volume of a 1.420 M NaOH solution is
required to titrate mL of a 4.50 M H2SO4
solution?
WRITE THE CHEMICAL EQUATION!
H2SO4 + 2NaOH H2O + Na2SO4 M
acid rx
coef. M
base
volume acid
moles acid
moles base
volume base
4.50 mol H2SO4
1000 mL soln x
2 mol NaOH
1 mol H2SO4 x
1000 ml soln
1.420 mol NaOH x
25.00 mL
= 158 mL
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7. Example 4.8)
In a titration experiment, a student finds that mL of a NaOH solution are needed to neutralize g of KHP. What is the concentration (in molarity, M) of the NaOH solution?
KHP = KHC8H4O4
Molar mass of KHP= g
KHP = potassium hydrogen phthalate (see p. 119). M
…now try 4.77!
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8. Gases
Chapter 5:

9. Elements that exist as gases at 250C and 1 atmosphere
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10. 11/21/2018

11. Physical Characteristics of Gases
Gases assume the volume and shape of their containers.
Gases are the most compressible state of matter.
Gases will mix evenly and completely when confined to the same container.
Gases have much lower densities than liquids and solids.
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