The lecture discusses the principles of solution concentration, defining terms such as dilute and concentrated solutions, and various methods of expressing concentration, including percentage, molarity, normality, and molality. It provides explanations and examples for each concentration expression type along with techniques for diluting solutions. The lecture concludes with a reminder to subscribe for further content and specifies its completion.

1. Physical Pharmacy Lecture Series
Lecture# 07
By: Pharmacist Tayyeb Official
Physico-chemical Principles (Solution)

2. Concentration Expression of Solution
• Dilute Vs Concentrated Solution
• Percentage Expression
• Molarity
• Normality
• Molality
• Mole Fraction
• Part per million
• Dilution of Solution

3. Concentration Expression:
“The amount of solute present in a
given amount of solution is called
concentration of the solution”.
Types of solution on basis of concentration:
Dilute Solution:
“A solution containing a relatively low concentration of
solute is called dilute solution”.
Concentrated solution:
“A solution containing relatively a higher concentration of
the solute is said ton be concentrated solution”.
Concentration Expression of Solution

4. Concentration Expression:
There are several ways of expressing concentration of
solution, some are as follows:
• Percentage Expression
• Molarity
• Normality
• Molality
• Mole Fraction
• Part per million
• Part per billion
Concentration Expression of Solution

5. Percentage Expression:
“The specific amount of solute
present in 100 gm of solution”.
OR
“It is the part of the solute present in
100 parts of the solution”.
Types:
Following are 03 different types of %age expressions:
• % age w/w
• % age v/v
• % age w/v
Concentration Expression of Solution

6. 1) %age w/w (m/m):
“Grams of solute in 100
grams of solution”.
• To calculate m/m% we use the following equation:
• Weight or mass of solute and mass of solution are in grams.
1) %age w/w (m/m):
“Grams of solute in 100
grams of solution”.
• To calculate m/m% we use the following equation:
• Weight or mass of solute and mass of solution are in grams.
Concentration Expression of Solution

7. 1) %age w/w (m/m):
Example:
Brass has a (w/w) % composition of
85% Cu and 15% Zn. If a sample of
brass contains 5.21g Cu, then what
mass of Zn is present in the sample?
See calculation video for the solution of this numerical.
Concentration Expression of Solution

8. 2) %age v/v:
“Milliliters of solute in
100 ml of solution”.
• To calculate % age v/v we use the following equation:
• Volume of solute and volume of solution are both in mL.
Concentration Expression of Solution

9. 2) %age v/v:
Example:
Beer usually contains 5.0%
(v/v) ethanol. How much
pure ethanol is present in one
341mL bottle of beer?
See calculation video for the solution of this numerical.
Concentration Expression of Solution

10. 3) %age w/v (m/v):
“Grams of solute in
100 ml of solution”.
To calculate % age w/v or m/v we use the following equation:
•Weight or mass of solute is in grams.
•Volume of solution is in mL
Concentration Expression of Solution

11. 3) %age w/v (m/v):
Example:
What mass of CuCl2(s) is
required to make 1.0L of 5.2%
(w/v) CuCl2 (aq)?
See calculation video for the solution of this numerical.
Concentration Expression of Solution

12. Molarity:
“The number of moles of solutes per liter of
solution is called molarity”.
The molarity of solution is represented by “M” and its units are
mole/liter (mol/L).
Written as 1 M NaOH.
One molar solution of sodium hydroxide.
One mole NaOH in 1 liter of solution.
Concentration Expression of Solution

13. Molarity:
Molar Concentration:
“The molar concentration of a solution is the
number of moles of solute that are dissolved in
1L of solution”.
• Amount of solute is in mol.
• Volume of solution is in L.
• Molar Concentration is in mol/L
Concentration Expression of Solution

14. Example of Molarity :
Making a 0.500 M Solution of NaOH?
Step 1: Determine mass needed
Step 2: Measure out 20.0 g NaOH using a balance
Step 3: Add less than one Liter of water to a volumetric flask.
Step 4: Dissolve 20.0 g (0.500 mol) of NaOH in the water.
Step 5: Fill volumetric flask to the line.
Concentration Expression of Solution

15. Example of Molarity :
Determine the molarity of solution prepared by
dissolving 75.5g of KOH in 540 ml of solution?
Solution:
No of moles of KOH = 75.5/56.1 = 1.35 moles
Volume of solution = 540/1000 = 0.54 liter
Molarity = 1.35/0.54 = 2.49 mol/liter
Concentration Expression of Solution

16. Normality:
“The no. of gram equivalent
of solute present per liter of the
solution”. It represented by “N”.
Concentration Expression of Solution

17. Normality:
Example:
Calculate the normality of H2SO4 solution, when
98g of H2SO4 is present in 500 ml?
Answer:
Equivalent weight of H2SO4 =98/2= 49
No. of gram equivalent of H2SO4 = 98/49 = 2
Volume of solution = 500 ml = 0.5 liter
Normality = 2/0.5 = 4 N
Concentration Expression of Solution

18. Molality:
“The number of moles of solutes per
kilograms of solvent is called molality”.
It is donated by “m”.
A solution of concentration 1mol/kg is also sometimes
denoted by 1 molal.
Example:
Calculate the molality of solution prepared by dissolving 5gm of toluene in 225 g
of solvent benzene (C6H6)? Mol. Wt. 92
Answer:
No. of moles of toluene = 5/92 = 0.054 mol
Weight of Benzene = 225/1000 = 0.225 kg
Molality = 0.054/0.225 = 0.24 mol/kg
Concentration Expression of Solution

19. Mole Fraction:
“ The ratio of no of moles of one
constituent and the total no of moles of all the
constituents of the solution”.
It is donated by “X”.
A solution consists of two components I & II. Their no of moles are
expressed as n1 & n2, so,
mole fraction of component I: x1 = n1/ n1+ n2,
mole fraction of components II: x2 = n2/n1+n2.
Total= Components I and II, x=x1+x2 = n1+ n2 / n1 + n2 = 1.
It is unit less quantity and total mole fraction of a solution will always be
unity.
X solute + X solvent = 1
Concentration Expression of Solution

20. Parts per million:
“Number of parts (by wt. or volume) of solute
per million parts (by wt or volume) of solution is called
parts per million.”
It is denoted by ppm.
Note:
Note that ppm does NOT refer to the number of particles, but the masses
of the solute and solution.
Significance:
1) It is used for very low concentration of solution.
2) It is used to express the amount of impurities in H2O.
Concentration Expression of Solution

21. Parts per billion (ppb):
“Number of parts (by wt. or volume) of solute
per billion parts (by wt or volume) of solution is called
parts per billion.”
It is denoted by ppb.
Note:
Note that ppb does NOT refer to the number of particles, but the masses of
the solute and solution.
Significance:
1) It is used for very low concentration of solution.
2) It is used to express the amount of impurities in H2O.
Concentration Expression of Solution

22. Parts per billion (ppb):
Example:
A 155.3g sample of pond water is found to
contain 1.7x10-4g of phosphates. What is
the concentration of phosphates in ppm?
In ppb?
See in calculation video series.
Concentration Expression of Solution

23. Diluting Solutions:
Diluting means to take a stock solution (a highly concentrated original
solution) and add more solvent to it.
Dilution of Solution

24. Diluting Solutions:
We using the following formula to calculate how to dilute a stock solution.
Ci or C1= initial concentration
Vi or V1 = initial volume
Cf or C2 = final concentration
Vf or V2 = final volume
Dilution of Solution

25. Diluting Solutions:
Example:
Calculate the volume of water
necessary to dilute 50 mL of a 0.50
mol/L sodium chloride solution to
0.30 mol/L.
See calculation video for solution of this.
Dilution of Solution

26. Solution
Other topic of solution:
Lecture# 07 (Done)
Lecture# 06 (prev.)

27. End
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