Solubility Curves

KentChemistry HOME

Custom Search

back to Kinetics and Equilibrium links

Solubility Curves (Table G)

Used to determine the mass of solute in 100g (100 ml) of water at a given temperature.

Definitions-

On the line=saturated (full can not hold anymore solute)

Below the line=unsaturated (can hold more solute)

Above the line= supersaturated (holding more solute than it should, unstable condition)

Below is Table G- This gives information based on 100 grams of water.

Warning-the Regents doesn't always ask about 100g.

Sometimes they ask about 50g (half of what is on the table) or 200g (double the amount on the table).

SOLIDS-Solids are generally more soluble in hot water than colder water. The curves that are increasing in solubility as temperature increases are solids.

Since lowering the temperature lowers the solubility, dissolved solids must recrystallize. This is how you make rock candy.

GASES- Gases are generally less soluble in hot water than colder water. The curves that are decreasing as temperature increases are gases.

Experiment of Soda (CO₂(aq)) at different temperatures showing this relationship.

	Substance	Solubility in 100g water
	KNO₃at 70°C	140g
	NH₄Cl at 90°C	72g
	NaCl at 100°C	40g
	KI at 20°C	145g
	NaNO₃at 35°C	100g
	SO₂ at 50°C	5g
	NH₃ at 20°C	55g
	KClO₃at 65°C	20g
	KCl at 75°C	50g
	NH₄Cl at 65°C	60g
	HCl at 10°C	78g
	NaNO₃at 70°C	135g
	KNO₃at 10°C	24g

6/02

According to Reference Table G, which solution is saturated at 30^oC?

(1) 12 grams of KClO₃ in 100 grams of water (3) 30 grams of NaCl in 100 grams of water

(2) 12 grams of KClO₃ in 200 grams of water (4) 30 grams of NaCl in 200 grams of water

Answer-->

Choice 1

8/02

One hundred grams of water is saturated with NH₄Cl at 50^oC. According to Table G, if the temperature is lowered to 10^oC, what is the total amount of NH₄Cl that will precipitate? (1) 5.0 g (2) 17 g (3) 30. g (4) 50. g

Answer-->

Choice 3; 52g-32g=30g

1/03

1 Solubility data for four different salts in water at 60^oC are shown in the table below.

Which salt is most soluble at 60^oC? (1) A (2) B (3) C (4) D

Answer-->

Choice D =0.5g/g H₂O

2 Base your answers on the information below. When cola, a type of soda pop, is manufactured, CO₂(g) is dissolved in it.

1. A capped bottle of cola contains CO₂(g) under high pressure. When the cap is removed, how does pressure affect the solubility of the dissolved CO₂(g)?

Answer-->

As pressure decreases solubility decreases

2. A glass of cold cola is left to stand 5 minutes at room temperature. How does temperature affect the solubility of the CO₂(g)?

Answer-->

As temperature increases solubility decreases

3. Draw a set of axes and label one of them "Solubility” and the other "Temperature."

4. Draw a line to indicate the solubility of CO₂(g) versus temperature on the axes drawn in part a.

Answer-->

The graph show the decrease in solubility as temperature increases

1/04

11 Which must be a mixture of substances? (1) solid (2) liquid (3) gas (4) solution

Answer-->

Base your answers to questions 56 through 58 on the information below.
A student uses 200 grams of water at a temperature of 60°C to prepare a saturated solution of potassium chloride, KCl.

56 Identify the solute in this solution.

Answer-->

The solute is KCl

57 According to Reference Table G, how many grams of KCl must be used to create this saturated solution?

Answer-->

45g X 2=90g (It is in 200g of water)

58 This solution is cooled to 10°C and the excess KCl precipitates (settles out). The resulting solution is saturated at 10°C. How many grams of KCl precipitated out of the original solution?

Answer-->

90g- (30gx2)=30g ppt.

6/04

Base your answers to questions 71 through 74 on the data table below, which shows the solubility of a solid solute.

71 Graph the data from the data table . Circle and connect the points.

Answer-->

Cannot answer here

73 Based on the data table, if 15 grams of solute is dissolved in 100 grams of water at 40°C, how many more grams of solute can be dissolved in this solution to make it saturated at 40°C?

Answer-->

9grams It can hold 24, so 24g-15g.

74 According to Reference Table G, how many grams of KClO₃ must be dissolved in 100 grams of H₂O at 10°C to produce a saturated solution?

Answer-->

About 6-8g

8/04

13 At room temperature, the solubility of which solute in water would be most affected by a change in pressure?

(1) methanol (l) (2) sugar (s) (3) carbon dioxide (g) (4) sodium nitrate (s)

Answer-->

Choice 3 gases are affected by pressure changes

1/05

15 A sample is prepared by completely dissolving 10.0 grams of NaCl in 1.0 liter of H₂O. Which classification best describes this sample?

(1) homogeneous compound (2) homogeneous mixture (3) heterogeneous compound (4) heterogeneous mixture

Answer-->

Choice 2

Two alcohols that are used in our everyday lives are rubbing alcohol and ethylene glycol. Rubbing alcohol is used as an antiseptic. Ethylene glycol is the main ingredient in antifreeze, which is used in automobile cooling systems.

77 Explain, in terms of molecular polarity, why rubbing alcohol, 2-propanol, is soluble in water.

Answer-->

it is polar, like dissolves like

6/05

14 The solubility of KClO_3(s) in water increases as the

                    (1) temperature of the solution increases 	(2) temperature of the solution decreases

                    (3) pressure on the solution increases 	(4) pressure on the solution decreases

Answer-->

Choice 1

41 According to Reference Table G, which substance forms an unsaturated solution when 80 grams of the substance is dissolved in 100 grams of H₂O at 10°C?

                    (1) KI          (2) KNO₃         (3) NaNO₃        (4) NaCl

Answer-->

Choice 1

1/06

14 A mixture of crystals of salt and sugar is added to water and stirred until all solids have dissolved. Which statement best describes the resulting mixture?

(1) The mixture is homogeneous and can be separated by filtration.

(2) The mixture is homogeneous and cannot be separated by filtration.

(3) The mixture is heterogeneous and can be separated by filtration.

(4) The mixture is heterogeneous and cannot be separated by filtration.

Answer-->

Choice 2

41 A student adds solid KCl to water in a flask. The flask is sealed with a stopper and thoroughly shaken until no more solid KCl dissolves. Some solid KCl is still visible in the flask. The solution in the flask is

(1) saturated and is at equilibrium with the solid KCl

(2) saturated and is not at equilibrium with the solid KCl

(3) unsaturated and is at equilibrium with the solid KCl

(4) unsaturated and is not at equilibrium with the solid KCl

Answer-->

Choice 1

Base your answers to questions 68 through 70 on the information and table below.

A student conducts an experiment to determine how the temperature of water affects the rate at which an antacid tablet dissolves in the water. The student has three antacid tablets of the same size and composition. The student drops one tablet into each of three beakers containing 200. milliliters of water at different temperatures and measures the time it takes for each tablet to completely dissolve. The results are shown in the table below.

68 Describe the effect of water temperature on the rate of dissolving.

Answer-->

The higher the temperature the faster it dissolves (higher rate)

69 Explain, in terms of collision theory, how water temperature influences the rate of dissolving.

Answer-->

More effective collisions between the solute and solvent

70 What change, other than temperature, would affect the rate of dissolving?

Answer-->

Surface area, stirring

6/06

40 A saturated solution of NaNO₃ is prepared at 60.°C using 100. grams of water. As this solution is cooled to 10.°C, NaNO₃ precipitates (settles) out of the solution. The resulting solution is saturated. Approximately how many grams of NaNO₃ settled out of the original solution?

(1) 46 g (2) 61 g (3) 85 g (4) 126 g

Answer-->

Choice 1; 125g - 79g=46g

Base your answers to questions 67 and 68 on the information below.

The graph shows the relationship between the solubility of a sequence of primary alcohols in water and the total number of carbon atoms in a molecule of the corresponding alcohol at the same temperature and pressure. A primary alcohol has the –OH group located on an end carbon of the hydrocarbon chain.

67 Describe the relationship between the solubility of a primary alcohol in water and the total number of carbon atoms in the primary alcohol.

Answer-->

As the number of Carbons increases solubility decrease

68 Determine the total mass of 1-pentanol that will dissolve in 110. grams of water to produce a saturated solution.

Answer-->

2.5g, penta refers to 5 carbons

8/06

41 An unsaturated aqueous solution of NH₃ is at 90.°C in 100. grams of water. According to Reference Table G, how many grams of NH₃ could this unsaturated solution contain?

(1) 5 g (2) 10. g (3) 15 g (4) 20. g

Answer-->

Choice 2

According to Reference Table G, a temperature change from 60°C to 90°C has the least effect on the solubility of

A. SO₂

B. NH₃

C. KCl

D. KClO₃

Answer-->

A Explanation: See Table G. Steep curves reflect the greatest effect. Solubility curves that change the least (y axis) reflect compounds for which temperature has the least effect. Notice how solubility of SO₂ decreases with an increase in temperature.

back to Kinetics and Equilibrium links

Chemical Demonstration Videos