Solution Concentration
0011 0010 1010 1101 0001 0100 1011
Section 15.2
1
2
4
Solution Concentration
0011
0010 1010
1101 0001 is0100
1011
Solution
Concentration
the measure
of how much solute is dissolved in a
specific amount of solvent.
Solutions can be described qualitatively using words concentrated and dilute.
-A concentrated solution would have a lot of solute compared to the
amount of solvent.
1
2
-A dilute solution would have very little solute compared to the
amount of solvent.
4
Expressing Concentration
0011 0010 1010 1101 0001 0100 1011
Concentration can be expressed in many different ways. Three that we
will use are percent by mass, percent by volume and molarity. Percent
by mass and volume both use the familiar phrase “part over whole
times a hundred” to obtain the answer.
1
2
Concentration is expressed as a percent in a ratio of measured amount
of solute to a measured amount of solution.
- Percent by mass = solid dissolved in a liquid
- Ratio of solute’s mass to the solution’s mass
- Mass of solution = masses of solute + mass of solvent
4
Percent by mass = mass of solute x 100
mass of solution
Molarity takes into account the number of particles (atoms and
molecules) present in the solution.
Percent by Mass Examples
1. What is the % concentration by mass of 8.3 g of NaCl dissolved in 300 g of water?
0011 0010 1010 1101 0001 0100 1011
2.
What is the % concentration by mass of 65 g of C6H12O6 dissolved in 500 g of
water?
3.
You have a 1000 g bleach solution. The % concentration by mass of the solute
NaOCl is 6.02 % . How many grams of the NaOCl are in the
solution?
1
4. How many grams of water would you have to add to 50 g of NaCl to
produce a solution concentration of 5%?
2
4
5. What is the solution concentration by mass of 12 grams of NaCl dissolved in 300
grams of water?
6.
If you need to produce 500 grams of an 8.3% saline solution, how many grams of
salt and how many grams of water would you use to form the solution?
Percent by Volume
1.
What is the percent by volume of ethanol in a solution that contains
35 mL of ethanol dissolved in 115 mL of water?
2.
If you have 100 mL of a 30% aqueous solution of ethanol, what
volumes of ethanol and water are in the solution?
3.
What is the percent by volume of isopropyl alcohol in a solution
that contains 24 mL of isopropyl alcohol in 1.1 L of water?
4.
What is the percent by volume of 140 mL of isopropyl alcohol
dissolved in 60 mL of water?
0011 0010 1010 1101 0001 0100 1011
1
2
4
Diluting Solutions
0011 0010 1010 1101 0001 0100 1011
In the laboratory, I purchase concentrated stock solutions of chemicals
because they are much more economical to buy. To use these solutions I
have to dilute them to concentrations that are required by the labs we
perform in class. To properly dilute these solutions I use the following
equation:
M1V1 = M2V2
1
2
4
Percent by Volume
0011 0010 1010 1101 0001 0100 1011
5.
What volume of a 3M KI solution would you use to make .3 L of a 1.25M
KI solution?
6.
How many milliliters of a 5M H2SO4 solution would you need to prepare
100 mL of .25M H2SO4?
7.
If you dilute 20 mL of a 3.5M solution to make 100 mL of solution, what
is the molarity of the dilute solution?
1
2
4
Molarity
0011 When
0010 1010
1101
0001
0100 with
1011a reaction in an aqueous solution, they
chemists
are
working
must know the number of particles (atoms, molecules) that are present.
Since we count the number of particles present using moles, then the
number of moles of solute dissolved per liter of solution is referred to as
MOLARITY (M) or molar concentration, The unit M is read as molar and
a liter of solution containing one mole of solute as a 1M sollution.
1
2
To calculate the molarity of a solution, we utilize the following formula:
4
Molarity = moles of solute
liters of solution
Molarity Practice
0011 0010 1010 1101 0001 0100 1011
What are the following relationships:
58 g NaCl in 1L = 1 Molar Solution
116g NaCl in 1L = _____ Molar Solution
58 g NaCl in .5L = _____ Molar Solution
116 g NaCl in _____ L = 2 Molar Solution
_____ g NaCl in 1 L = 1 Molar Solution
_____ g NaCl in 1 L = .5 Molar Solution
29 g NaCl in _____ L = 1 Molar Solution
1
2
4
Molarity
This is a typical molarity problem:
0011 0010 1010 1101 0001 0100 1011
1.
What is the molarity of a solution containing 58 grams of salt in 1 Liter
of solution?
2.
What is the molarity of a glucose solution containing 12.8 g of glucose in
1.5 liters of an aqueous soluton?
3.
Calculate the molarity of 100 mL of a solution containing 50 g of H2SO4.
4.
What is the molarity of 500 mL of a solution containing 125 g of MgSO4?
1
2
4
5. What is the solution concentration of 45 g of NaCl in 350 mL of water?
Molarity
6.
How many grams of salt would be dissolved in 1.0 L of a 0.5M solution of
0011 0010
1010 1101 0001 0100 1011
NaCl?
7.
If the solubility of O2 is 8.3 g/L at 3 atm, how many g/L will dissolve at 10
atm?
8.
How many grams of CaCO3 are contained in one liter of a 4M CaCO3
solution?
9.
How many grams of Na3PO4 should be dissolved in 800 mL of water to
make a .3M solution of Na3PO4?
1
2
4
10. How many grams of LiCl are in 750 mL of a 4.0M LiCl solution?
Molarity
If the
solubility
of N0100
g/L at 3 psi, how much pressure is needed to
2 is 2.3
001111.
0010
1010
1101 0001
1011
dissolve 8.0 g/L?
12. How many grams of water must be added to 12 grams of salt to make a
15% solution concentration?
1
2
13. How many grams of C6H12O6 are needed to make a 600 mL of .3M
aqueous solution of C6H12O6?
4
14. How many grams of CCl4 are in 300 mL of a 5M CCl4 solution?
15. How many grams of NH3 can be produced with 500 g of N2 and an
unlimited amount of H2?