Concentration units and comparison of concentration units

Concentration Units

1. CONCENTRATION UNITS AND COMPARISON OF CONCENTRATION UNITS

2. SOLUTION A solution is a homogenous mixture made of particles that exist as individual molecules or ions. Composed of a solute and a solvent.

3. Solution SATURATED SOLUTION UNSATURATED SOLUTION SUPERSATURATED SOLUTION Maximum amount of dissolved solute Less solute than saturated solution More dissolved solute than saturated solution

4. Solution DILUTE CONCENTRATED contains a relatively small amount of dissolved solute contains a relatively large amount of dissolved solute

5. CONCENTRATION UNITS Percent by mass Percent by volume Mole fraction Molarity Molality Parts per million

6. Percent by mass expresses the concentration as percentage of solute in a given mass of solution. It is computed by dividing the mass of the solute by the mass of the solution.

7. Percent by mass Sample Problem: What is the percent by mass of sodium chloride in a solution that is made by dissolving 2.35 g of NaCl in 7.45 g of H2O?

8. Percent by mass

9. Percent by volume Solutions that are formulated from two liquids are often expressed as volume percent with respect to the solute. The volume percent is the volume of a liquid in 100mL of solution. This method gives the volume of liquid solute dissolved in a definite volume of solution.

10. Percent by volume

11. Percent by volume Sample Problem: An antifreeze is a substance added to a liquid to lower its freezing point. If 4.00 L of antifreeze is added to enough water to make 12.0 L of solution, what is the percentage by volume of the solution?

12. Percent by volume

13. Mole Fraction (X) the ratio of the number of moles of one component of a solution to the total number of moles of all the components. The mole fraction of the solute is the number of moles of solute divided by the total number of moles of solute and solvent. The sum of the mole fractions of solute and solvent is equal to 1 in a solution that contains a single solute dissolved in a solvent.

14. Mole Fraction (X)

15. Mole Fraction (X) Sample Problem: Calculate the mole fraction of both H2SO4 and H2O in a 100g sample of a 10% H2SO4 solution.

16. Molarity Molarity (M) is defined as the number of moles of solute in one liter of solution.

17. Molarity Sample Problem: You have 3.50 L of solution that contains 90.0 g of sodium chloride, NaCl. What is the molarity of that solution?

18. Molality Molality (m) is the concentration of a solution expressed in number of moles of solute per kilogram of solvent.

19. Molality Sample Problem: What is the molality of a solution containing 75.5 g sucrose in 400.0 g water?

20. Parts per Million and Parts per Billion ways to express concentration of very dilute solutions. parts per million (or mg/L) is obtained by multiplying the ratio of the mass of solute to the mass of solution by 10 6 . parts per billion (or μg /L) is obtained by multiplying the same ration by 10 9 . They are particularly useful in expressing concentrations of trace amounts of a substance relative to the total amount.

21. Parts per Million and Parts per Billion Sample Problem: What is the concentration in ppm and ppb of a 2 kg solution containing 6.0 mg of a solute?