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DEFINITION A solution is a homogeneous mixture of two or more substance in a single physical state.

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Presentation on theme: "DEFINITION A solution is a homogeneous mixture of two or more substance in a single physical state."— Presentation transcript:

1 DEFINITION A solution is a homogeneous mixture of two or more substance in a single physical state

2 Parts of a solution SOLUTE – the substance that is dissolved SOLVENT- the substance that does the dissolving

3 Definitions Solute - KMnO4 Solvent - H2O

4 TYPES OF SOLUTIONS SOLUTE SOLVENT EXAMPLE GAS Air LIQUID Seltzer (CO2)
Antifreeze (ethyl glycol in water) SOLID Sea water ( salt in water) Charcoal filter (poisonous gases in carbon) Dental filling (mercury in silver) Sterling silver (copper in silver)

5 GASEOUS SOLUTIONS All mixture of gases
Properties depend on the properties of its components Example: Nitrogen in air serves as a gas that dilutes pure oxygen which is toxic to people and animals, and is very combustible.

6 LIQUID SOLUTIONS Most familiar type of solution
The solvent and the solution are liquids Solute may be a gas, a solid, or a liquid It is proper to describe liquids that are soluble to each other as MISCIBLE or can mix. And insoluble liquids as IMMISCIBLE. Or cannot mix. Example: alcohol is miscible in water while oil is immiscible in water.

7 Important terminologies:
Soluble – substance that dissolves another substance Insoluble – substance that does not dissolve another substance Miscible – liquids that are completely soluble in each other or can mix Immiscible – liquids that are not soluble in each other or cannot mix

8 AQUEOUS SOLUTIONS Solutions with water as the solvent
Aqueus, means like or containing water. Substances that dissolve in water are classified according to whether they produce ions or molecules in solution. Solutions that conduct electricity are called ELECTROLYTES.

9 SOLUBILITY

10 Solubility Solubility maximum grams of solute that will dissolve
in 100 g of solvent at a given temperature varies with temp based on a saturated solution

11 SUPERSATURATED SOLUTION
Solubility UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form increasing concentration

12 The Effect of Temperature on Solubility
Generally, increasing the temperature will increase solubility of solids and liquids. But increasing temperature will lower the solubility of gases (the gas will escape from solution, going back to the gas phase).

13 FACTORS AFFECTING DISSOLUTION:
Particle size – area of solute particles exposed to the action of the solvent particles. Increase in surface area of the solute particles , solubility increases Example: fine table salt dissolves faster than rock salt

14 2. Stirring or Agitation increases the solubility of solid solute particles in a solvent. Because it hastens the contact between the surface of the solute and the solvent particles

15 3. Application of heat - solvent molecules move faster and come in contact frequently with the solute particles, increasing solubility. Except for other solutes where solubility hastens with decrease in the temperature of the solvent. Example: sodium hydroxide pellets dissolves slowly in hot water than in cold water.

16 of solubility on temperature
Solubility vs. Temperature for Solids 140 KI 130 120 gases solids NaNO3 110 Solubility Table 100 KNO3 90 80 HCl NH4Cl shows the dependence of solubility on temperature 70 Solubility (grams of solute/100 g H2O) 60 NH3 KCl 50 “Solubility Curves for Selected Solutes” Description: This slide is a graph of solubility curves for 10 solutes. It shows the number of grams of solute that will dissolve in 100 grams of water over a temperature range of 0cC to 10 cC. Basic Concepts The maximum amount of solute that will dissolve at a given temperature in 100 grams of water is given by the solubility curve for that substance. When the temperature of a saturated solution decreases, a precipitate forms. Most solids become more soluble in water as temperature increases, whereas gases become less soluble as temperature increases. Teaching Suggestions Use this slide to teach students how to use solubility curves to determine the solubilities of various substances at different temperatures. Direct their attention to the dashed lines; these can be used to find the solubility of KClO3 at 50 cC (about 21 g per 100 g of H2O). Make sure students understand that a point on a solubility curve represents the maximum quantity of a particular solute that can be dissolved in a specified quantity of solvent or solution at a particular temperature. Point out that the solubility curve for a particular solute does not depend on whether other solutes also are present in the solution (unless there is a common-ion effect; this subject usually is covered at a later stage in a chemistry course). Questions Determine the solubilities (in water) of the following substance at the indicated temperatures: NH3 at 50 oC; KCl at 90 oC; and NaNO3 at 0 oC. Which of the substances shown on the graph is most soluble in water at 20 oC? Which is lease soluble at that temperature? For which substance is the solubility lease affected by changes in temperature? Why do you think solubilities are only shown between 0 oC and 100 oC? In a flask, you heat a mixture of 120 grams of KClO3 and 300 grams of water until all of the KClO3 has just been dissolved. At what temperature does this occur? You then allow the flask to cool. When you examine it later, the temperature is 64 oC and you notice a white powder in the solution. What has happened? What is the mass of the white powder? Compare the solubility curves for the gases HCl, NH3, and SO2) with the solubility curves for the solid solutes. What generalizations(s) can you make about the relationship between solubility and temperature? According to an article in an engineering journal, there is a salt whose solubility in water increases as the water temperature increases from 0 oC to 65 oC. The salt’s solubility then decreases at temperatures above 65 oC, the article states. In your opinion, is such a salt likely to exist? Explain your answer. What could you do to verify the claims of the article? 40 30 NaCl KClO3 20 10 SO2 LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517

17 How to determine the solubility of a given substance?
Find out the mass of solute needed to make a saturated solution in 100 cm3 of water for a specific temperature(referred to as the solubility). This is repeated for each of the temperatures from 0ºC to 100ºC. The data is then plotted on a temperature/solubility graph,and the points are connected. These connected points are called a solubility curve.

18

19 How to use a solubility graph?
A. IDENTIFYING A SUBSTANCE ( given the solubility in g/100 cm3 of water and the temperature) Look for the intersection of the solubility and temperature.

20 Example: What substance has a solubility of 90 g/100 cm3 of water at a temperature of 25ºC ?

21

22 Example: What substance has a solubility of 200 g/100 cm3 of water at a temperature of 90ºC ?

23

24 B. Look for the temperature or solubility
Locate the solubility curve needed and see for a given temperature, which solubility it lines up with and visa versa.

25 What is the solubility of potassium nitrate at 80ºC ?

26 At what temperature will sodium nitrate have a solubility of 95 g/100 cm3 ?

27 At what temperature will potassium iodide have a solubility of 230 g/100 cm3 ?

28 What is the solubility of sodium chloride at 25ºC in 150 cm3 of water ?
From the solubility graph we see that sodium chlorides solubility is 36 g.

29 Place this in the proportion below and solve for the unknown solubility. Solve for the unknown quantity by cross multiplying. Solubility in grams = unknown solubility in grams 100 cm3 of water other volume of water ___36 grams____ 150 cm3 water The unknown solubility is 54 grams. You can use this proportion to solve for the other volume of water if you're given the other solubility.

30 C. Determine if a solution is saturated, unsaturated,or supersaturated.
If the solubility for a given substance places it anywhere on it's solubility curve it is saturated. If it lies above the solubility curve, then it's supersaturated, If it lies below the solubility curve it's an unsaturated solution. Remember though, if the volume of water isn't 100 cm3 to use a proportion first as shown above.

31 Sometimes you'll need to determine how much additional solute needs to be added to a unsaturated solution in order to make it saturated. For example,30 grams of potassium nitrate has been added to 100 cm3 of water at a temperature of 50ºC.

32 How many additional grams of solute must be added in order to make it saturated?
From the graph you can see that the solubility for potassium nitrate at 50ºC is 84 grams

33 If there are already 30 grams of solute in the solution, all you need to get to 84 grams is 54 more grams ( 84g-30g )

34 of solubility on temperature
Solubility vs. Temperature for Solids Solubility (grams of solute/100 g H2O) KI KCl 20 10 30 40 50 60 70 80 90 110 120 130 140 100 NaNO3 KNO3 HCl NH4Cl NH3 NaCl KClO3 SO2 gases solids Solubility Table shows the dependence of solubility on temperature “Solubility Curves for Selected Solutes” Description: This slide is a graph of solubility curves for 10 solutes. It shows the number of grams of solute that will dissolve in 100 grams of water over a temperature range of 0cC to 10 cC. Basic Concepts The maximum amount of solute that will dissolve at a given temperature in 100 grams of water is given by the solubility curve for that substance. When the temperature of a saturated solution decreases, a precipitate forms. Most solids become more soluble in water as temperature increases, whereas gases become less soluble as temperature increases. Teaching Suggestions Use this slide to teach students how to use solubility curves to determine the solubilities of various substances at different temperatures. Direct their attention to the dashed lines; these can be used to find the solubility of KClO3 at 50 cC (about 21 g per 100 g of H2O). Make sure students understand that a point on a solubility curve represents the maximum quantity of a particular solute that can be dissolved in a specified quantity of solvent or solution at a particular temperature. Point out that the solubility curve for a particular solute does not depend on whether other solutes also are present in the solution (unless there is a common-ion effect; this subject usually is covered at a later stage in a chemistry course). Questions Determine the solubilities (in water) of the following substance at the indicated temperatures: NH3 at 50 oC; KCl at 90 oC; and NaNO3 at 0 oC. Which of the substances shown on the graph is most soluble in water at 20 oC? Which is lease soluble at that temperature? For which substance is the solubility lease affected by changes in temperature? Why do you think solubilities are only shown between 0 oC and 100 oC? In a flask, you heat a mixture of 120 grams of KClO3 and 300 grams of water until all of the KClO3 has just been dissolved. At what temperature does this occur? You then allow the flask to cool. When you examine it later, the temperature is 64 oC and you notice a white powder in the solution. What has happened? What is the mass of the white powder? Compare the solubility curves for the gases HCl, NH3, and SO2) with the solubility curves for the solid solutes. What generalizations(s) can you make about the relationship between solubility and temperature? According to an article in an engineering journal, there is a salt whose solubility in water increases as the water temperature increases from 0 oC to 65 oC. The salt’s solubility then decreases at temperatures above 65 oC, the article states. In your opinion, is such a salt likely to exist? Explain your answer. What could you do to verify the claims of the article? LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517

35 Classify as unsaturated, saturated, or supersaturated.
Solubility vs. Temperature for Solids Solubility (grams of solute/100 g H2O) KI KCl 20 10 30 40 50 60 70 80 90 110 120 130 140 100 NaNO3 KNO3 HCl NH4Cl NH3 NaCl KClO3 SO2 gases solids Classify as unsaturated, saturated, or supersaturated. 80 g 30oC 45 g 60oC 50 g 10oC 70 g 70oC =unsaturated per 100 g H2O =saturated =unsaturated =supersaturated

36 Solubility vs. Temperature for Solids
Solubility (grams of solute/100 g H2O) KI KCl 20 10 30 40 50 60 70 80 90 110 120 130 140 100 NaNO3 KNO3 HCl NH4Cl NH3 NaCl KClO3 SO2 gases solids So sat. 40oC for 500 g H2O = 5 x 66 g = 330 g 120 g < 330 g unsaturated saturation 40oC for 100 g H2O = 66 g KNO3 Per 500 g H2O, 120 g 40oC

37 Describe each situation below.
(A) Per 100 g H2O, 100 g Unsaturated; all solute 50oC. dissolves; clear solution. (B) Cool solution (A) very Supersaturated; extra slowly to 10oC solute remains in solution; still clear. (C) Quench solution (A) in Saturated; extra solute an ice bath to 10oC. (20 g) can’t remain in solution, becomes visible.

38 a. 80 g b. 42 g 2. b. 42 g KNO3 = 25g KNO3 = g 100 g H2O x g H2O 3. a mg at 30oC b. 9.2 mg 20oC 9.2 mg O = x mg O2 1,000 g H2O 1,000 g H2O= =0.92 mg O2


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