Solutions Unit:

Focus Learning Targets:

Define a solution and give examples.

Define solute and solvent and determine the solute and solvent for a given solution

Define molarity using a mathematical equation and give the appropriate units.

Perform calculations involving solution dilution.

Define dissociation and describe the interactions between water and ionic compounds that lead to dissociation.

Write dissociation equations for ionic compounds and represent dissociation equations

Calculate the concentration of ions in a solution from the concentration of an ionic compound.

Calculate the concentration of ions resulting from mixing two solutions by applying solution dilution and dissociation

equations.

Compare unsaturated and saturated solutions.

Determine if a compound is soluble or insoluble in water using a solubility table.

Describe the effect of temperature on solubility. Determine the solubility of a compound at a given temperature from a

solubility curve.

Write the formula equation, complete ionic equation, and net ionic equation for a precipitation reaction, giving the

appropriate state for each substance.

Perform stoichiometric calculations involving molarity of solution

Solutions WS-1

1. Define the following terms

a. Solute

b. Solvent

c. Solution

d. Saturated solution

e. Unsaturated solution

f. Homogeneous mixture

g. Heterogeneous mixture

h. Soluble

i. Polar molecule

j. Concentrated solution

k. Dilute solution

l. Immiscible

m. allloy

2. Identify the solute and solvent in the following solutions:

a. 30.0 g of sugar & 80.0 g of water solute: __________ solvent: _________

b. 80 g of water & 15.0 g of NaCl solute: __________ solvent:__________

c. 28.0 L of nitrogen & 17.0 L of oxygen solute: __________ solvent: _________

d. A steel composition containing 0.95 % carbon, 0.1 % silicon, 0.015 % phosphorus, 0.4 % molybdenum, with the

remainder percent by weight being iron. solute:__________ solvent:___________

3. Name three things that will affect the solubility of a substance.

4. How does increasing the temperature of a solid affect its solubility? What about for a gas?

5. What’s the difference between a solution, a suspension, and a colloid? Give examples of each.

Solution Concentration W.S-2

There are different ways to find the concentration of a solution

1. Molarity describes the concentration of a solution in moles of solute divided by liters of solution and not moles of solute per

liter of solvent. This is the most widely used unit for concentration when preparing solutions in chemistry and biology. The

units of molarity, mol/L, are usually represented by “M”.

Formula: Molarity= moles / L of solution

Example: 10 grams of NaOH is dissolved in enough water to make 2 L of solution

a. 13.5g of NaCl is dissolved in enough water to make .383 L of solution.

What is the molarity (M) of the solution?

How many moles of NaCl are contained in 0.0200 L of the above NaCl solution?

What volume (L) of this NaCl solution would contain 0.300 moles of NaCl?

b. 15.5g of glucose (C6H12O6) is dissolved in enough water to make 950.0 mL of solution.

c. If 0.675 moles of copper (II) nitrate are dissolved in enough water to make 50.0 mL of solution, what is the molarity of the

solution?

d. What is the molarity of a 500.0 mL solution in which 2.70 moles of sodium hydroxide are dissolved?

e. How many grams of magnesium nitrate are needed to make 4.30 L of a 0.20 M solution?

f. Tell how you would prepare a 1000.0mL of 0.750 M ammonium chloride solution. Include all necessary equipment and

amount of chemical (in grams).

2. Percent Solutions W.S-3

Percent composition is the ratio of one part of solute to one hundred parts of solution and is expressed as a percent.

Determine the mass of solute and solution and then divide the mass of the solute by the total mass of the solution. This

number is then multiplied by 100 and expressed as a percent. In dilute water solutions, we can assume that 1 mL of water-

based solution has a mass of 1 gram, so 1 liter of solution has a mass of 1000 grams. This is frequently used with commercial

products.

Example: What is the mass percent of a solution of 7.6 grams sucrose in 83.4 grams of water

% Mass= mass of the solute X 100

mass of the solution

% Mass = 7.6 g X100

(7.6 + 83.4)

a. If 40.0 grams of ammonium hydroxide are added to 200. mL of water, what is the percent by mass of this solution?

b. An alcohol-water solution is by volume 30.0% isopropyl alcohol. There are 750. mL of the solution. How many mL of

alcohol were added to water when preparing the solution?

c. If 35.0 mL of ethanol, C2H5OH, were added to 65.0 mL of water, what is the percent by volume of the solution?

d. Brass is made up of zinc and copper. If the concentration of zinc is relatively low, the brass has a golden color and is often

used for inexpensive jewelry a 25.0 g of a necklace contains 2.9 g of zinc, what is the percentage mass by mass of zinc in

brass?

e. How many grams of beryllium chloride are needed to make 125 g of a 22.4% solution?

f. If 10.6 grams of ethanol would be mixed with 225 mL of water what is the% mass of the solution?

g. You have 200g of a solution that contains 30g of hydrochloric acid (HCl), what percentage of your solution is made up of

hydrochloric acid?

3. Parts per million (ppm), is a ratio of parts of solute to one million parts of solution, and is usually applied to very

dilute solutions. It is often found in reports of concentration of water contaminants. To calculate parts per million, divide the

mass of the solute by the total mass of the solution. This number is then multiplied by 106 and expressed as parts per million

(ppm). In dilute water solutions, we can assume that 1 mL of water-based solution has a mass of 1 gram, so 1 liter of solution

has a mass of 1000 grams.

Notice that calculations of ppm are the same as percent composition, except that you multiply by 1 million instead of by 100.

ppm = g solute x 106

g solution

Example: 25 grams of a chemical is dissolved in 75 grams of water. What is the concentration of the chemical in parts per

million (ppm)?

__25__ X 1000000 = 250 ppt

(25+75)

a. The solubility of AgCl is 0.008 grams/100 grams of water. What is this concentration in ppm?

b. 35 grams of ethanol is dissolved in 115 grams of water. What is the concentration of ethanol in parts per billion (ppb)?

c. .A certain pesticide has a toxic solubility of 5.0 grams/Kg of body weight. What is this solubility in ppm?

4. Molarity:

a. What is the molarity of a solution in which 0.45 grams of sodium nitrate are dissolved in 265 mL of solution?

b. What will the volume of a 0.50 M solution be if it contains 25 grams of calcium hydroxide?

c. How many grams of ammonia(NH3) are present in 5.0 L of a 0.050 M solution?

d. What is the molarity of 245.0 g of Sulfuric acid dissolved in 1.000 L of solution?

e. 45.0 g of Ca(NO3)2 was used to create a 1.3 M solution. What is the volume of the solution?

Solution Dilution W.S-4

Many of the regularly used solutions are prepared as concentrated solutions. These concentrated solutions are referred to as stock

solutions. Often times a lab or a demo calls for a less concentrated solution. The stock solutions are diluted (often with water) to make

the desired solution. The process of adding more solvent to a solution is called a dilution.

Note:The moles stay the same! The only difference is that there is more or less solvent!

Example: A chemist starts with 50.0 mL of a 0.40 M KCl solution and dilutes it to 1000. mL. What is the concentration of KCl in the

new solution?

(Mcon) (Vcon) = (Mdil) (Vdil)

(0.40 M) (50.0 mL) = (Mdil) (1000. mL)

0.020 M = Mdil

1. A solution of 1.00 M KCl is available. How many milliliters of this solution are needed to make a total of 100.0 mL of 0.750 M

NaCl solution. 75.0 mL

2. If 27.5 mL of 16.0 M nitric acid stock solution is added to 300. mL of water, what is the molarity of the diluted solution? (V1 will

be 27.5 mL. But for V2 don’t forget to add the volume of the water and the nitric acid to get the total V2 volume.)

2. What volume of 0.250 M NaCl is needed to make 100.0 mL of 0.100 M NaCl solution? 40.0mL

3. Concentrated H2SO4 is 18.0 M. What volume of 18 M solution is needed to make 2.00 L of 1.00 M H2SO4 solution? 0.11L

4. Concentrated HNO3 is 12.0 M. What volume of 12 M solution is needed to make 2.00 L of 1.00 M HNO3 solution? 0.167L

5. A solution of 10.0 M KOH is prepared. From this solution, you need to make 250.0 mL of 0.375 M KOH solution. How many mL

will be required? 9.38mL

6. How much water would I need to add to 500 mL of a 2.4 M KCl solution to make a 1.0 M solution? 700mL

7. How much additional water must be added to 30.0ml of a 12M HCl solution to make a 0.35M HCl diluted solution? 999mL

8. 2.5 L of solution contains 170 g of sodium nitrate. What is the initial concentration of the solution? If the solution is diluted to give

a final volume of 4.0 L, what is the final concentration? 0.80 M, 0.50 M

9. 200 mL of solution contains 10.7 g of potassium iodate. Calculate the initial concentration of the solution. Calculate the final

concentration if 300 mL of water are added to the solution. 0.250 M, 0.100 M

10. How much additional water would we need to add to 500mL of 2.4M KCl concentrated solution to make a 1.0M diluted solution? 700mL

11. We leave 750 mL of 0.50M NaCl solution uncovered on a windowsill and 150mL of the solvent evaporates. Determine the final

molarity concentration of the solution. Will it be more or less concentrated? 0.625 M, more

Challenging:

12. Calculate the final concentration if 2.00 L of 3.00 M NaCl and 4.00 L of 1.50 M NaCl are mixed. 2.0M

13. Calculate the final concentration if 2.00 L of 3.00 M NaCl, 4.00 L of 1.50 M NaCl and 4.00 L of water are mixed. 1.20M

Solution Dissociation:

13. Write balanced chemical equations to represent the slight dissociation or the complete dissociation for the following compounds

a. silver chloride

b. sodium acetate

c. sodium hydroxide

d. iron(II) sulfate

e. ammonium sulfate

14. Write a dissociation equation for each the following compounds. Calculate the concentration of each ion in solution.

a. What is the concentration of each ion in a 10.5 M sodium sulfite solution? 10.5M 21.0M

b. What is the concentration of each ion in the solution formed when 94.78g of Iron(111)sulfate is dissolved into 55.0mL of water? 0.4309 M, 0.8619M,1.293 M

c. If the chloride concentration in 2.00L of solution is 0.900M, calculate the [Al3+] and the molarity of the AlCl3 solution. 0.0300M, 0.0900M

d. The [Cl-] = 0.600 M in 100.0 mL of AlCl3 solution. How many grams AlCl3 are in the solution? 2.67g

e. The [SO42-] = 0.600 M in 100.0mL of a Al2(SO4)3 solution. How many grams Al2(SO4)3 are in the solution? 6.85g

f. If 1.78L of 0.420 M barium fluoride is added to 2.56L of water, what is the resulting concentration of each ion?

0.172M , 0.172M, 034

Solubility W.S-5

When two solutions of ionic compounds are mixed, a solid may form. This type of reaction is called a precipitation

reaction, and the solid produced in the reaction is known as the precipitate. You can predict whether a precipitate will

form using a list of solubility rules such as those found in the table below. When a combination of ions is described as

insoluble, a precipitate forms. There are three types of equations that are commonly written to describe a precipitation

reaction.

The molecular equation shows each of the substances in the reaction as compounds with physical states written next to

the chemical formulas. The complete ionic equation shows each of the aqueous compounds as separate ions. Insoluble

substances are not separated and these have the symbol (s) written next to them. Notice that there are ions that are present

on both sides of the reaction arrow –> that is, they do not react. These ions are known as spectator ions and they are

eliminated from complete ionic equation by crossing them out. The remaining equation is known as the net ionic

equation.

1. Classify each of the substances as being soluble or insoluble in water by writing (s) for remains solid or ‘aq’ for

dissociates

a. KBr =

b. PbCO3 =

c. BSO3 =

d. zinc hydroxide =

e. sodium acetate =

f. copper (II) sulfide =

g. Mg3(PO4)2 =

h. KOH =

i. NiCl2 =

j. NH4OH =

k. Hg2SO4 =

l. PbI2 =

Solubility Rules

1. All salts of Group IA, and ammonium are soluble.

2. All salts of nitrates, chlorates and acetates are soluble.

3. All salts of halides are soluble except those of silver(I), copper(I), lead(II), and mercury(I).

4. All salts of sulfate are soluble except for barium sulfate, lead(II) sulfate, and strontium sulfate.

5. All salts of carbonate, phosphate and sulfite are insoluble, except for those of group IA and ammonium. 6.

All oxides and hydroxides are insoluble except for those of group IA, calcium, strontium and barium.

7. All salts of sulfides and insoluble except for those of Group IA and IIA elements and of ammonium

2. Directions: Write balanced molecular, ionic, and net ionic equations for each of the following reactions. Assume

all reactions occur in aqueous solution. Include states of matter in your balanced equation.

Example: The reaction of lead(11)nitrate with sodium chloride to form lead(11)chloride and sodium nitrate

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

1. Sodium hydroxide and lead II nitrate

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

2. Sodium carbonate and Iron II chloride

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

3. Potassium oxalate and calcium chloride

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

4. Ammonium phosphate and zinc nitrate

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

5. Lithium hydroxide and barium chloride

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

6. Magnesium nitrate and sodium chromate

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

7. Nickel nitrate and sodium hydroxide

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

8. Iron III chloride and magnesium metal

Molecular Equation:

Complete Ionic Equation:

Net Ionic Equation:

9. Barium Bromide and sodium sulfate

Molecular Equation:

Complete Ionic Equation:

Solubility and Temperature W.S-6

Use the solubility curve below to answer the following questions

1. In general, how does temperature affect solubility?

2. Which compound is least soluble at 10°C?

3. How many grams of KCl can be dissolved in 100g of water at 80°C?

4. How many grams of NaCl can be dissolved in 100g of water at 90°C?

5. At 40°C, how much KNO3 can be dissolved in 100g of water?

6. Which compound shows the least amount of change in solubility from 0°C-100°C?

7. At 30°C, 90g of NaNO3 is dissolved in 100g of water.

Is this solution saturated or unsaturated?

8. At 60 C, 72 g of NH4Cl are dissolved in 100g of water.

This solution is considered to be:

A) saturated; B) unsaturated; C) supersaturated;

9. A saturated solution of KClO3 is formed from one hundred grams of water. If the saturated solution is cooled from 90°C to 50°C, how many grams of precipitate are formed?

1 A saturated solution of NH4Cl is formed from one hundred grams of water. If the saturated solution is cooled from 80°C to 40°C, how many grams of precipitate are formed?

12. Which compounds show a decrease in solubility from 0°C-100°C?

A) potassium chlorate B) cerium sulfate C) sodium nitrate D) ammonia E) Both B and D

13. Which compound is the most soluble at 10°C?

A) Ce2(SO4)3 B) NaCl C) KCl D) KClO3 E) NH3

14. A chemist adds 120 grams of KCl into a test tube which contains 100 grams of water. The temperature of the water is 80°C. How much of the solute will be left undissolved at the bottom of the test tube?

A) 50 grams B) 60 grams C) 70 grams D) 80 grams E) 56 grams

15. Use the solubility curve below to answer the following questions

34. B Which salt is least soluble at 20°C?

a. Which salt is least soluble at 20°C? A) NaClO3 B) KNO3 C) KBr D) NaCl B

b. How many grams of KBr can be dissolved in 100g of water at 60°C? about 90 g

c. How many grams of NaCl can be dissolved in 100 g of water at 100°C? 40 g d. Classify the type of solution: At 40°C, 180g of NaClO3 is dissolved in 100g of water. C

A) saturated B) unsaturated C) supersaturated D) saturated with some left undissolved

e. Classify the type of solution: At 70°C, 70g of KBr is dissolved in 100g of water. B

A) saturated B) unsaturated C) supersaturated D) saturated with some left undissolved

f. A saturated solution of NaClO3 is formed from one hundred grams of water. If the saturated solution

Is cooled from 80°C to 60°C, how many grams of precipitate are formed? 30 g

g. A chemist adds 160 grams of KNO3 into a test tube which contains 100 grams of water. The temperature of the water is

50°C. How much of the solute will be left undissolved at the bottom of the test tube?

A) 50 grams B) 60 grams C) 70 grams D) 80 grams E) 56 grams B

Solutions Unit Review Honors Chemistry

1. Explain how ionic compounds dissolve in water.

2. What three factors influence the rate of dissolution?

3. What are the two components of a solution? Define each component.

4. As the temperature increases, what happens to the solubility of a solid? Of a gas?

5. Explain the meaning of the phrase “like dissolves like”?

6. Define saturated, unsaturated and supersaturated solution.

7. What volume of a 6.0M NaCl solution can be made from 3.51g of NaCl?

8. How many grams of KOH are needed to make a 250ml 1.5M solution of KOH?

9. What volume of 1.500M NaCl is needed for a reaction that requires 146.3g NaCl?

10. Find the mass of Mg(OH)2 in 150ml of 2.0M Mg(OH)2 solution.

11. What is the molar concentration (molarity) of a 125ml solution made by dissolving 34.2g of sucrose, C12H22O11, in water?

12. How would you prepare 100.ml of a 0.500M HNO3 solution if you have a 12.0M stock solution of HNO3?

13. What mass, in grams, of sodium sulfate is needed to make 275 g of a 1.5% (m/m) aqueous solution of sodium sulfate? 4.1 g

14. What is the molar concentration of a barium chloride solution that is prepared by adding 20.0 mL of water to 50.0 mL of a 10.0 M barium chloride solution? (Assume volumes are additive) 7.14 M

15. What mass, in grams, of calcium nitrate are there in 867 mL of a 2.00 M calcium nitrate solution?(Molar mass calcium nitrate = 164.09 g/mole) 285 g

16. Two sulfuric acid solutions are mixed as follows: 25.0 mL of a 0.50 M sulfuric acid solution are added to 0.075 L of a 0.25 M sulfuric acid solution. What is the molarity of the resulting mixture?(Assume volumes are additive)

0.32 M

17. What volume, in liters, of a 2.00 M KCl solution contains 2.5 g of KCl? (Molar mass KCl = 74.55 g/mole) Answer: 0.017 L solution

18. What volume, in mL, of 0.250 M silver nitrate solution is needed to react with 45.0 mL of 0.187 M potassium phosphate solution? (Molar masses: AgNO3 = 169.87 K3PO4 = 212.27 Ag3PO4 = 418.58 KNO3 = 101.10)

3AgNO3(aq) + K3PO4(aq) Ag3PO4(s) + 3 KNO3(aq) 101 mL

19. 76.91 mL of a 0.556 M oxalic acid solution are required to react with 28.43 mL of a sodium hydroxide solution. What is the molar concentration of the sodium hydroxide solution? (Molar masses: H2C2O4 = 90.04 NaOH = 40.00 H2O = 18.02 Na2C2O4 = 134.00) H2C2O4(aq) + 2 NaOH(aq) 2 H2O(l) + Na2C2O4(aq) 3.01 M

20. What mass, in grams, of lead (II) chromate can be produced fr om 12.00 mL of 10.0 M potassium chromate solution with 120.00 mL of 2.00 M lead(II) nitrate solution? (Molar masses: K2CrO4 = 194.19 Pb(NO3)2 = 331.21 KNO3 = 101.10 PbCrO4 = 323.19)

K2CrO4 (aq) + Pb(NO3)2(aq) 2 KNO3(aq) + PbCrO4(s)

38.8 g

21. Find the molar concentration of each of the ions in a solution that contains 0.165 moles of aluminum chloride in 820 mL solution. 0.201 M Al3+, 0.603 M Cl-

22. Find the molar concentration of each of the ions in a solution that results from mixing 27 mL of 0.25 M HNO3 with 36 mL of 0.42 M Ca(NO3)2. (Assume volumes are additive.) 0.11 M H+, 0.59 M NO3

-, 0.24 M Ca2+

23. Find the molarity of each of the ions present in a solution prepared by mixing 3 5 mL of 0.42 M K2SO4 with 27 mL of 0.17 M K3PO4. (Assume volumes are additive.) 0.71 M K+, 0.24 M SO4

2-, 0.074 M PO43-

24. 28.00 mL of 0.670 M potassium carbonate solution is mixed with 15.00 mL of 0.940 M cobalt(III) chloride. a. Write the molecular, total and net ionic equations for the reaction that occurs.

b. Identify any solid formed in the reaction and calculate its mass.

c. Calculate the molar concentration of each ion remaining in solution after the reaction is complete.

b. 1.87 g of Co2(CO3)3; c. 0.874 M K+, 0.0372 M Co3+, 0.986 M Cl-, 0 M CO32-

25.

25. Use the solubility graph to answer the following questions:

1. Which substance is most soluble at 60º C ? 2. Which two substances have the same solubility at 80º C? 3. Which substance’s solubility changes the most from 0º C to 100ºC? 4. Which substance’s solubility changes the least from 0º C to 100º C? 5. What is the solubility of potassium nitrate at 90º C? 6. At what temperature does potassium iodide have a solubility of 150 g/ 100 cm3 water? 7. You have a solution of sodium nitrate containing 140 g at 65º C. Is the solution saturated, unsaturated ,or

supersaturated? 8. You have a solution of potassium chlorate containing 4 g at 65º C. How many additional grams of solute must

be added to it, to make the solution saturated?