General Chemistry Name

General Chemistry Name :

Worksheet : Ch. 15-16 ; Molarity Date :

A. Percent composition of solutions:

1. What is the percent composition (m/v) of a 500.0 mL solution which contains 5.0 g of glucose?

2. How many grams of glucose is there in 500.0 mL of a 3.0% (g/mL) solution of glucose?

3. What is the percent composition of a solution made by dissolving 100.0 mL of ethanol in 400.0 mL of water?

A. Molarity:

1. ______( ___ ) is the ratio of the number of moles of solute to the number of liters of solution.

2. _____ (T/F) A 0.50 M ( read "point five molar") solution is made by putting 0.50 moles of solute into one liter of solvent.

3. _____ (T/F) A 0.50 M solution is formed by dissolving 0.50 moles of solute in a volume of solvent which is less than one liter, and then diluting so that the total volume of the solution (solute and solvent) equals one liter.

4. Write the mathematical equation for calculating molarity and rearrange this equation to solve for moles and liters.

5. Change the equation for the calculation of moles of solute to calculate grams of solute.

5a. Write the equation used in dilution problems :

B. Sample problems : Solve the following problems dealing with molarity.

6a. A solution contains 0.20 mol of glucose in 500.0 mL of the solution. What is the molarity of this solution?

6b. A solution contains 3.36 g of NaF in 155 mL of solution. What is the molarity of this solution?

6c. How many grams of NaF are there in 568 mL of a 1.5 M solution of NaF?

6d. How many grams of NaOH are there in 200.0 mL of a 25 % (g/mL) solution?

6e.What is the molarity of a solution formed by diluting 250.0 mL of a 0.50 M solution to a

volume of 500.0 mL?

C. Problems :

7. What is the molarity of a solution which contains 2.2 mol of sodium fluoride in 4.0 L of the solution?

8. What is the molar concentration of a solution which contains 3.50 g of calcium chloride in 250.0 mL of solution?

9. What is the molar concentration of a solution which contains .55 g of magnesium oxide in 2.50 L of solution?

10. What is the molarity of a solution which contains 0.88 g of barium chloride in 120.0 mL of solution?

11. How many grams of silver fluoride are there in 250 mL of a .0010 M solution of silver fluoride?

12. How many grams of sodium sulfide are there in 850.0 mL of a 0.20 molar solution of sodium sulfide?

13. How many grams of lithium are there in 250.0 mL of a 0.50 M solution of lithium iodide?

D. Dilution and percent problems.

14. A student has a stock solution which has a concentration of 1.5 M. How many mL must she dilute to get 500.0 mL of a 0.50 M solution?

15. A student leaves 20.0 mL of a 0.010 M solution of sodium hydroxide in an open beaker over a three day weekend. This causes the volume to reduce to 8.5 mL. Assuming no loss of the solute, what is the new molarity of the solution?

16. What is the percent by volume concentration of a solution made by dissolving 15.0 mL of methanol in 90.0 mL of water?

17. How much ethanol is in 1.0 liters of gas if the gas solution is 12.0% ethanol?

18. What is the percent (m/v) concentration of caffeine and of sucrose of a solution made by dissolving 0.015 g of caffeine and 15.0 g of sucrose in enough water to form 473 mL of solution?

19. How many grams of glucose are there in 3.5 liters of blood if blood has a concentration of 0.010% (g/L)?

Answers : 7. 0.55 M 8. 0.126 M 9. 5.5 x 10-3 M 10. 0.035 M 11. 0.032 g 12. 13 g 13. 0.87 g 14. 170 mL 15. 0.024 M 16. 0.50 M Na+, 0.20 M Al3+, 0.55 M SO42- 17.14.3% 18. 0.12 L 19. 3.2 x 10-3 % caffeine, 3.2% sucrose 209. 3.5 x 10-4 g glucose