Transcript S o l u t i o n s - Crescent Public Schools

Solution
A homogeneous
mixture of two or
more substances.
For Any Solution
Solvent - the substance
present in the most amount.
Solute - the substance
present in the least amount.
For Any Solution
Solvent - there can be
only ONE
Solute - there can be
MORE than one
Solvent - the substance
present in the most amount.
What is the solvent
in air?
Solute - the substance
present in the least amount.
Solvent - the substance
present in the most amount.
What are the solutes
in air?
Solute - the substance
present in the least amount.
Solvent - the substance
present in the most amount.
What is the solvent
in stainless steel?
Solute - the substance
present in the least amount.
Solvent - the substance
present in the most amount.
What are the solutes
in stainless steel?
Solute - the substance
present in the least amount.
Aqueous Solution
Solvent - Water
Solute - The substance
dissolved in water
Solubility
The amount of solute that
can be dissolved in a given
amount of solvent, at a
given temperature.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Is NaCl
soluble
in H2O?
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Saturated Solution
A solution containing the
maximum amount of a solute
that is possible to dissolve in a
given volume of solvent at a
given temperature.
Saturated Solution
NaCl has a
solubility of
357 grams
per liter of
"cold" H2O.
+
Saturated Solution
How many
moles of
NaCl are
in the
solution?
NaCl
solution
Saturated Solution
357 g NaCl 1 mole NaCl
=
58 g NaCl
6.2 mole NaCl
NaCl
solution
Saturated Solution
How many
"particles"
of NaCl are
in the
solution?
NaCl
solution
Saturated Solution
23
10
357 g NaCl
6.02 X
particles NaCl
58 g NaCl
24
10
3.7 X
particles NaCl
NaCl
solution
=
Concentration
A comparison of
the amounts of
solute and solvent
in a solution.
Concentration
"Strong" and "Weak"
give SOME comparison,
but only a general idea.
Concentration
"Dilute" and "Concentrated"
still don't provide enough
for quantitative calculations.
Concentration
To do calculations, we must
know "how much" solute
and "how much" solvent
are present.
Molarity
M =
moles solute
3
dm
solution
1 mole = formula mass (g)
1 liter = 1 cubic decimeter
dm3
1 liter = 1000 milliliters
1 ml = 1 cm3
Molarity =
moles
dm3
1. What is the molarity
of a liter of
solution containing
100 grams of
copper (II) chloride?
Molarity =
100g CuCl2
1 liter
moles
dm3
Molarity =
moles
dm3
100g CuCl2
1 liter
grams
Molarity =
100g CuCl2
1 liter
moles
dm3
mole
grams
Molarity =
100g CuCl2
1 liter
moles
dm3
1 mole
grams
Molarity =
100g CuCl2
1 liter
moles
dm3
1 mole
134g
Cu = 1 X 64 = 64
Cl = 2 X 35 = 70
134
Molarity =
100g CuCl2
1 liter
moles
dm3
1 mole
1 liter
134g
1 dm3
Molarity =
100g CuCl2
1 liter
moles
dm3
1 mole
1 liter
134g
1 dm3
Have we worked
the problem?
Molarity =
100g CuCl2
1 liter
moles
dm3
1 mole
1 liter
134g
1 dm3
.75M CuCl2
How is this problem
different from the first?
2. How much NaCl is
needed to prepare
250ml of
0.5M salt water
The first ASKS for M
1. What is the molarity of a liter of
solution containing 100 grams of
copper (II) chloride?
The second GIVES M
2. How much NaCl is needed to prepare
250ml of 0.5M salt water?
2.How much NaCl is
needed to prepare
250 ml of
0.5 M salt water
Preparation
250 ml 0.5 mole NaCl
dm3
Preparation
250 ml 0.5 mole NaCl
dm3
What units will we have
when the problem is worked?
Preparation
250 ml 0.5 mole NaCl
dm3
need grams
Preparation
250 ml 0.5 mole NaCl
dm3
need grams
Preparation
250 ml 0.5 mole NaCl
dm3
1 mole NaCl
need grams
Preparation
250 ml 0.5 mole NaCl 58 g NaCl
dm3
1 mole NaCl
need grams
Preparation
250 ml 0.5 mole NaCl 58 g NaCl
dm3
1 mole NaCl
Now What?
need grams
Preparation
250 ml 0.5 mole NaCl 58 g NaCl
dm3
1 dm3
1 mole NaCl 1000 ml
need grams
Preparation
250 ml 0.5 mole NaCl 58 g NaCl
dm3
1 dm3
1 mole NaCl 1000 ml
7.3 grams NaCl
Practice
Problems
Practice Problem 1
0.37 g CaCl2
340 ml
1 mole
1000 ml
110 g
0.01 M CaCl2
1 dm3
Practice Problem 2
50 cm3
0.2 mole Al(OH)3 78 g Al(OH)3
dm 3
mole
0.78 g Al(OH)3
1 dm 3
1000 cm3
Homework
Problems
Homework Problem 1
50 g NaOH
200 cm3
1 mole
40 g
1000 cm3
1 dm3
6.25 M NaOH
Homework Problem 2
100 cm3
0.25 mole CaSO4
dm3
3.4 g CaSO4
136 g
mole
1 dm3
1000 ml
Homework Problem 3
100 ml
0.5 mole HCl
dm3
1.8 g HCl
36 g
mole
1 dm3
1000 ml
Making Dilutions
Making Dilutions
A solution can be made
less concentrated by
dilution with solvent
Making Dilutions
M 1 V1 = M 2 V2
original solution 1 = diluted solution 2
Volume units must be the same for
both volumes in this equation.
Dilution Problem
How do you prepare
100ml of 0.40M MgSO4
from a stock solution
of 2.0M MgSO4?
Dilution Problem
M1 V1 = M2 V2
M1 =
M2 =
V1 =
V2 =
Dilution Problem
M1 V1 = M2 V2
M1 = 2.0M MgSO4
M2 = 0.40M MgSO4
V1 = unknown
V2 = 100ml
Dilution Problem
Step 1 - write the equation:
M1 V1 = M2 V2
Step 2 - manipulate the equation:
V1 = M2 V2 /M1
Step 3 - add the numbers:
V1 = (0.40M) (100ml) /2.0M
Dilution Problem
Step 4 - do the calculation:
V1 = 20ml
Step 5 - describe the preparation:
Add 80ml of distilled water to 20ml
of the 2.0 M MgSO4 solution
Homework
Problems
Molarity Calculations:
1. 0.975M (NH4)2C4H4O6
2. 0.257M CoSO4
3. 0.291M Fe(NO3)2
Preparations:
1. 390g NiCl2
2. 95.3g AgF
3. Use 50cm3 of the 1.0M
NaCl solution. Add
200cm3 of distilled water
to make the total volume
250cm3.
Dilutions:
1. Add 19.2cm3 of 0.52M CoCl2 solution
to a graduate. Add distilled water to
make the total volume 100cm3.
2.
Add 72.5cm3 of 0.69M Ba(NO3)2
solution to a graduate. Add distilled
water to make the total volume
200cm3.
3.
Add 37.5ml of 2M NH4Br solution to a
graduate. Add distilled water to make
the total volume 500ml.
Solution Preparation
Other Solution
Concentrations
Molality
m =
moles solute
Kg solvent
Normality
N =
equivalents solute
3
dm
solution