1. 12.1 Expressing Concentration The Amount of Solute in the solvent
Dr. Fred Omega Garces
Chemistry 201
Miramar College

2. Components of Solution
Mixtures: Variable components, retains properties of its component.
Homogeneous systems: Solutions
Solution - Homogeneous mixture of two or more substances Components of solution
Solute - Substance being dissolve
Solvent - Substance in which solute is dissolved in.
If solvent is water, then solution is considered aqueous.

3. 9 Types of Solution (derived from 3 phases)
Solute
Solvent
Solution
gas O2 in
gas N2
Air
gas CO2 in
Liquid H2O
Carbonated Water
liquid H2O in
Gas Air
Fog
liquid EtOH in
Wine
Liquid Hg in
Solid Ag
Dental-filling
Solid NaCl in
Brine
Solid Ag in
Solid Au
14 Karat gold

4. Solution & Concentration
Concentration - Proportion of substance in mixture
or amount of solute in given amount of solvent.
Most common type: Molarity (M)
Molarity - moles solute / Liter solution
Example: What mass (g) of copper(II)sulfate pentahydrate
(250. g/mol) is needed to make 1.00-L of 0.10M solution?

5. Expressing Concentration
5 ways of expressing concentration-
Molarity (M) - moles solute / Liter solution
Molality* (m) - moles solute / Kg solvent
Conc. by parts (% m)- (solute [mass] / solution [mass]) * 100
w/v [mass solute (g) / volume solution (ml)] * 100
v/v [vol solute (mL) / vol solution (mL)] * 100
mole fraction (A) - moles solute / Total moles solution
Normality (N) - Number of equivalent / Liter solution
Note that molality is the only concentration unit in which denominator contains only solvent information rather than solution.
It is also a concentration unit together with mole fraction that are temperature independent.

6. Concentration Relationship
moles
mass  m %m M*
} Solute
} Solvent
Molecular Weight
Molc’ Wt
MassSolution
Density Solution
VolSolution N
Equivalence/mol
* Volume of solution must be used and not just volume of solvent

7. Concentration Relationship
* Volume of solution must be used and not just volume of solvent

8. Calculating molality (m): Example
3.5 g of CoCl2 ( g/mol) is dissolved in water to produce 100-ml solution. Assume the density of the solution is 0.95g/mL, what is molal concentration of the solution?

9. Calculating molality (m): Example
3.5 g of CoCl2 ( g/mol) is dissolved in water to produce 100-ml solution. Assume the density of the solution is 0.95 g/mL, what is molality concentration of the solution?
mol CoCl2 = 3.5 g CoCl2 • mol CoCl2 g
= mol = mol
mass H2O = (100ml • g) g
1 mL
= g
m = 3.5 g CoCl2 • mol CoCl2 •
g kg
= m = molal

10. Concentration by Parts
Solute (mass or volume)
Solution (mass or volume)
x multiplier
% Concentration
w/w = Wt Solute• g •100  % (pph)
Wt Soln g
w/v = Wt Solute• g • 100  % (pph)
Vol Soln ml
v/v = Vol Solute• ml • 100  % (pph)
ppm & ppb (For dilute solution)
m/m = mass Solute • g •106  ppm
(ppm) mass Soln g
v/v = Vol Solute• ml • 109  ppb
(ppb) Vol Soln ml

11. Calculating % Concentration: Example
3.5 g of CoCl2 is dissolved in a solvent to form a 100-ml solution. Assume the density of the solution is 0.95 g/mL, what is concentration of the solution in % mass? …
%m = 3.5 g CoCl2
95 g Solution
= 3.7% (m/m)
x 100
Example #3
What is the v/v concentration if one drop of alcohol (1/20 ml = ml) is added to 1.00L? % or ppm
Ans:
%(v/v) = (0.05mL/1000mL)•100
= % (pph)
ppm (v/v)= (0.05 mL/1000 mL)•106
= 50 ppm
Answer
3.7% m/v CoCl2

12. % Concentration: % Mass Example
Example#2: What is the v/v (%) & (ppm) concentration if one drop of alcohol (1/20 ml = 0.05 ml) is added to 1.00L?
Anws:
%(v/v) = (0.05mL/1000mL)•100
= % (pph)
ppm(v/v)= (0.05mL/1000mL)•106
= 50 ppm
Example#3: The legal BAC in California cannot exceed .080% of a person’s blood by volume. How much alcohol (oz & mL) if a 160lb person has 4.7 L blood and has 0.12% BAC.
1 L = 1000ml, mL = 1.0 oz
5.64 mL or oz
Example#1
3.5 g of CuSO4 is dissolved in 100mL solution. Assume the density of the solution is 1.0 g/mL, what is concentration of the solution in % mass?
%m = 3.5 g CuSO4
100g Solution
= 3.5% (m/m)

13. Shark Sense pp(?): Making Chem Relevant
Example#4
A shark can smell blood in water from several miles away. What is the concentration of 1 drop blood in 1mi3 volume ?
Ans:
ppt= (0.05mL/4.17•1015ml)•109
= ppb
= ppt
*Quintillion (1 •1018)
= 12 ppquintlllion

14. Expressing Normality Normality: Equivalent:
The number of equivalents of acid or base solute in one litter of solution.
Equivalent:
The number of specie (acid or base) that gives one mole of charge.
Note: HCl : 1mol HCl = 1eq H+
H2SO4: 1 mol H2SO4 = 2 eq H+
H3PO4: 1 mol H3PO4 = 3 eq H+
Mg+2 : 1 mol Mg+2 = 2 eq charge
NaOH: 1 mol NaOH = 1 eq OH-
Therefore: 5.0 M HCl = 5mol HCl • 1eq = N HCl
1 L mol
and
5.0 M H2SO4 = 5mol H2SO4 • 2eq = N H2SO
1 L mol

15. Interconverting Concentration: A Calculation Example
A perchloric acid (HClO4 MWt = g/mol) solution is 10.0 % m/m. The density of the solution is g/cc. What is the Molarity, molality, mole fraction and Normality of the solution?
Answer
10.00 g ® 9.95•10-2 mole
100 g solution ® cc
Molarity = M
® 9.95•10-2 mole ® Kg H2O
molality = 1.11 m
® 9.95•10-2 mole
® 5.00 mol H2O
cA = .0195

16. Interconverting Concentration: More Examples
If sodium thiosulfate (Na2S2O3, MW = g/mol) solution ( molal) contains 800. ml water, what is the mole fraction and the mass of the solute for this solution?
Example#7:
What is the % mass and the molality of a cK2CO3 = solution which contains exactly g of water?
MWK2CO g/mol

17. ...and ever more Examples Example#8:
50.00ml of ethylene glycol ( = g/mL; MW = g/mol) is added to L water ( = 1.00 g/mL) at 20°C. Answer the following questions and assume additive volumes.
i) What is the density of the mixture
ii) Calculate the % mass of the ethylene glycol in the solution.
iii) Calculate the molarity and molality of ethylene glycol in the solution.

18. Misc Problems Answers Harris 7th ed p18
1. The density of 70.5 wt% aqueous perchloric acid, HClO4, is 1.67 g/mL
(a) How many grams of solution are in L g
(b) How many grams of HClO4 are in 1.000L? g
(c) How many moles of HClO4 in 1.000L? mol
2. An aqueous solution containing 20.0% wt% KI has a density of g/mL. Find the molality, mole fraction, and molarity of the KI solution m
3. The concentration of sugar (glucose, C6H12O6) in human blood ranges from about 80mg/100mL before meal to 120mg/100mL after eating. Find the molarity before and after eating e-3M, 6.7e-3M
4. It is recommended that drinking water contain 1.6 ppm fluoride (F-) for preventing of tooth decay. Consider a reservoir with a diameter of 4.50•102 m and and average depth of 10.0 m. (V = p r2 h) How many grams of fluoride should be added to give 1.6 ppm? How many grams of sodium fluoride, NaF contains this much fluoride? 1.25, 2.5e6 g F-, 5.6e6 g NaF
5. How many mL of 3.00 M H2SO4 are required to react with 4.35 g of solid containing 23.2 m:m% Ba(NO3)2 if the reaction produces BaSO4 precipitate. 133, mL

19. Solution at a Glance Solutions can be describe by the following:
Solvent
The component of a solution present in the greatest quantity
Solute
The component of solution present in the lesser quantity
Solution
A homogeneous mixture of two or more substances in which each substance retains its chemical identity
Concentration of a Solution
The amount of solute in a specific amount of solution.
Molarity
(M)
moles of solute
Liters of solution