WORSHEET 1: CONCENTRATION PROBLEMS WITH SOLUTION
1. What is the percentage concentration of 75 g of ethanol dissolved in 500 g of water? answer: 13.0 % ethanol
2. A chemist dissolves 3.50 g of potassium iodate and 6.23 g of potassium hydroxide in 805.05 g of water. What is the percentage concentration of each solute in the solution? answer: 0.430 % KIO3 and 0.765 % KOH
3. A student wants to make a 5 % solution of rubidium chloride using 0.377 g of the substance. What mass of water will be needed to make the solution? answer: 7.16 g H2O
4. What mass of lithium nitrate would have to be dissolved in 30 g of water in order to make an 18 % solution? answer: 6.59 g LiNO3
5. A solution of sodium hydroxide, NaOH, contains 12 grams of solute in 4 litres of solution. What is the concentration of the solution in g/L? answer: 3 g/L
6. A solution of sugar contains 35 grams of sucrose, C12H22O11 in 100 mL of solution. What is the concentration of the solution in g/L? answer: 350 g/L
7. If the percent by volume is 2 % and the volume of solution is 250mL what is the volume of solute in this solution? answer: 5 mL
8. If I make a solution by adding water to 35 mL of methanol (CH3OH) until the final volume of the solution will be 275 mL. What is the percent by volume of methanol in this solution? answer: 12.7 %
9. What weight of solute is needed to produce each of the indicated solutions? How many grams of water should be used in each of the cases?
a) 500 g of a 6.40 % NaCl solution. answer: 32 g NaCl and 468 g H2O
b) 136 g of a 14.2 % LiNO3 solution. answer: 19.3 g LiNO3 and 116.7 g H2O
c) 42.2 g of a 7.60 % AgNO3 solution. answer: 3.2 g AgNO3 and 39 g H2O
10. What would be the percentage concentration by mass of each of the following solutions? Remember that the density of water is 1 g/mL.
a) 54 g of AgNO3 g is dissolved in 128 g of water. answer: 29.67 %
b) 4.22 g of K2CO3 is dissolved in 426 mL of water. answer: 0.98 %
c) 0.762 g of ZnF2 is dissolved in 1.30 litres of water.
WORSHEET 2: CONCENTRATION PROBLEMS WITH SOLUTION
1) A solution with 3 g of potassium chloride (KCl) in 100 g of water is prepared. Calculate the percent of mass of solute in the solution. (result: 2,91%)
2) A glucose solution is 30% mass. How much glucose and water has 100 g of solution? (result: 30 g glucose and 70 g water)
3) We need to prepare 250 g of an aqueous solution of sodium bromide with a 5% mass concentration. How much solute and solvent do we need? (result: 12,5 g of NaBr and 237,5 g of water)
4) A liter of milk has a mass of 1060 g and a 1,6 percent of mass in fat. Calculate the mass concentration of fat in g/L. (result: 17 g/L of fat)
5) Vinegar is a solution with a 3% mass of acetic acid. How much acid is in 150 g of vinegar? (result: 4,5 g of acetic acid)
6) A solution has been prepared with 30 g of sugar solved in water till we get 200 ml of solution. Which is its mass concentration of sugar in g/L? (result: 150 g/L of sugar)
7) We weight 5 g of sodium chloride and water is added till we have 250 ml of solution. What mass concentration of sodium chloride we get? (result: 20 g/L of NaCl)
8) We need to prepare 150 ml of a 20 g/L solution of iodine. How much iodine and water do we need? (result: 3 g of I2 and 150 ml of water)
9) We need to prepare 300 ml of a ferric sulfate solution for fertilizing plants with a 12 g/L mass concentration. How much ferric sulfate mass do we need? (result: 3,6 g of ferric sulfate)
10) When 33g of sugar are dissolved in 198 g of water we get 0,22 liters of solution. Calculate the mass concentration and the percent of mass of the solution. (result: 150 g/L of sugar and 13 % of sugar)
11) The solubility of potassium nitrate at 20°C is 250 g/L. Calculate the mass of potassium nitrate we must dissolve in 400 ml of water for having a saturated solution at 20°C
SOLUTIONS
SOLUTIONS
WORKSHEET 1: CONCENTRATION PROBLEMS WITH ANSWER
1. What is the percentage concentration of 75 g of ethanol dissolved in 500 g of water? answer: 13.0 % ethanol
2. A chemist dissolves 3.50 g of potassium iodate and 6.23 g of potassium hydroxide in 805.05 g of water. What is the percentage concentration of each solute in the solution? answer: 0.430 % KIO3 and 0.765 % KOH
3. A student wants to make a 5 % solution of rubidium chloride using 0.377 g of the substance. What mass of water will be needed to make the solution? answer: 7.16 g H2O
4. What mass of lithium nitrate would have to be dissolved in 30 g of water in order to make an 18 % solution? answer: 6.59 g LiNO3
5. A solution of sodium hydroxide, NaOH, contains 12 grams of solute in 4 litres of solution. What is the concentration of the solution in g/L? answer: 3 g/L
6. A solution of sugar contains 35 grams of sucrose, C12H22O11 in 100 mL of solution. What is the concentration of the solution in g/L? answer: 350 g/L
7. If the percent by volume is 2 % and the volume of solution is 250mL what is the volume of solute in this solution? answer: 5 mL
8. If I make a solution by adding water to 35 mL of methanol (CH3OH) until the final volume of the solution will be 275 mL. What is the percent by volume of methanol in this solution? answer: 12.7 %
9. What weight of solute is needed to produce each of the indicated solutions? How many grams of water should be used in each of the cases?
a) 500 g of a 6.40 % NaCl solution. answer: 32 g NaCl and 468 g H2O
b) 136 g of a 14.2 % LiNO3 solution. answer: 19.3 g LiNO3 and 116.7 g H2O
c) 42.2 g of a 7.60 % AgNO3 solution. answer: 3.2 g AgNO3 and 39 g H2O
10. What would be the percentage concentration by mass of each of the following solutions? Remember that the density of water is 1 g/mL.
a) 54 g of AgNO3 g is dissolved in 128 g of water. answer: 29.67 %
b) 4.22 g of K2CO3 is dissolved in 426 mL of water. answer: 0.98 %
c) 0.762 g of ZnF2 is dissolved in 1.30 litres of water.
TAKE A REVIEW
WORSHEET 2: CONCENTRATION PROBLEMS WITH SOLUTION
1) A solution with 3 g of potassium chloride (KCl) in 100 g of water is prepared. Calculate the percent of mass of solute in the solution. (result: 2,91%)
2) A glucose solution is 30% mass. How much glucose and water has 100 g of solution? (result: 30 g glucose and 70 g water)
3) We need to prepare 250 g of an aqueous solution of sodium bromide with a 5% mass concentration. How much solute and solvent do we need? (result: 12,5 g of NaBr and 237,5 g of water)
4) A liter of milk has a mass of 1060 g and a 1,6 percent of mass in fat. Calculate the mass concentration of fat in g/L. (result: 17 g/L of fat)
5) Vinegar is a solution with a 3% mass of acetic acid. How much acid is in 150 g of vinegar? (result: 4,5 g of acetic acid)
6) A solution has been prepared with 30 g of sugar solved in water till we get 200 ml of solution. Which is its mass concentration of sugar in g/L? (result: 150 g/L of sugar)
7) We weight 5 g of sodium chloride and water is added till we have 250 ml of solution. What mass concentration of sodium chloride we get? (result: 20 g/L of NaCl)
8) We need to prepare 150 ml of a 20 g/L solution of iodine. How much iodine and water do we need? (result: 3 g of I2 and 150 ml of water)
9) We need to prepare 300 ml of a ferric sulfate solution for fertilizing plants with a 12 g/L mass concentration. How much ferric sulfate mass do we need? (result: 3,6 g of ferric sulfate)
10) When 33g of sugar are dissolved in 198 g of water we get 0,22 liters of solution. Calculate the mass concentration and the percent of mass of the solution. (result: 150 g/L of sugar and 13 % of sugar)
11) The solubility of potassium nitrate at 20°C is 250 g/L. Calculate the mass of potassium nitrate we must dissolve in 400 ml of water for having a saturated solution at 20°C