Physical Science, CP Chapter 22 SOLUTIONS Se ction 1: How Solutions Form Section 2: Solubility and Concentration Section 3: Particles in Solution Section 4: Dissolving Without Water

1. Which items in this picture are the same throughout? Which are unevenly mixed? 2. Do you think the salad is the same kind of mixture as the vinegar? Why? 3. What invisible mixture do you depend on every moment of every day?

Section 1: How Solutions Form Standard 3: Demonstrate an understanding of various properties and classifications of matter. Indicators: 3.1, 3.5 Objectives: Determine how things dissolve. Examine the factors that affect the rates at which solids and gases dissolve in liquids.

Solution-a mixture that appears the same throughout and is mixed at the molecular level Solute - substance being dissolved Solvent - substance doing the dissolving

Solutions can be liquids, gases, or solids. Alloys are solid solutions

Water molecules are polar-they have a positive area and a negative area. Water molecules cluster around solid molecules, with their negative ends attracted to the positive ends of the solids. Water molecules pull the solid particles into solution. The moving water molecules and solid molecules spread out and mix evenly to form a solution.

Rate of dissolving depends on: Speeds up dissolving by bringing more fresh solvent into contact with more solute. Dissolving occurs at the surface of a solid. Breaking a solid into pieces or powder increases its surface area, which speeds up dissolving. Increasing the temperature of a solvent speeds up the movement of its particles.

To mix solids to make an alloy solution, you must melt the solids. To make a gas dissolve more quickly in a liquid, cool the liquid solvent and increase the pressure of the gas.

Review Questions 1. A mixture that has the same composition, color, and density throughout is called a __________. solution

Review Questions 2. The substance being dissolved in a solution is called the __________. solute

Review Questions 3. Which of these factors does not affect solubility? A. container size B. crystal size C. surface area D. temperature A. container size

Review Questions 4. The substance doing the dissolving is called the ____________. solvent

Review Questions 5. Why is water called the universal solvent? Water can dissolve many polar solutes

1. Why does it take so much sap to make one gallon of maple syrup? 2. Why does a solution become more concentrated through evaporation?

Section 2: Solubility and Concentration Standard 3: Demonstrate an understanding of various properties and classifications of matter. Indicators: 3.1, 3.5 Objectives: Define the concept of solubility. Identify how to express the concentration of solutions. List and define three types of solutions. Describe the effects of pressure and temperature on the solubility of gases.

Solubilities of two substances can be compared by measuring. Solubility-the amount of a substance that can dissolve in a solvent Depends on the nature of the substances

A concentrated solution has a large amount of solute in the solvent. A dilute solution has a small amount of solute in the solvent. Concentrations can be expressed as percent by volume of the solute.

SaturatedUnsaturated Supersaturated contains all the solute it can hold at a given temperature. As the temperature of a liquid solvent increases, the amount of solid solute that can dissolve in it increases.

Solubility curve - line on a graph used to figure how much solute can dissolve at any temperature on the graph

able to dissolve more solute at a given temperature Supersaturated solution - contains more solute than a saturated one at the same temperature M ade by raising temperature of a saturated solution, adding more solute, and lowering temperature back without disturbing the solution Unstable - will crystallize if disturbed As it crystallizes, it gives off energy and produces heat.

To make a gas dissolve more quickly in a liquid, cool the liquid solvent. To make a gas dissolve more quickly in a liquid, increase the pressure of the gas.

Review Questions 1. What is solubility? Solubility is the maximum amount of a solute that can be dissolved in a given amount of solvent at a given temperature.

Review Questions 2. What are the three types of solutions? Saturated, Unsaturated, and Supersaturated Solutions

Review Questions 3. A(n) __________ solution is any solution that can dissolve more solute at a given temperature. A. electrolyte B. saturated C. supersaturated D. unsaturated

Review Questions 4. Which is true of a supersaturated solution? A. conducts electricity in water B. can dissolve more solute at a given temperature C. cannot form crystals when additional solute is added D. unstable

Review Questions 5. Name one way to make a solid solute more soluble. Heat the solvent

1. What are the advantages of salting a road during freezing weather? Disadvantages? 2. Why don’t the oceans freeze at 0°C? 3. Is it impossible to freeze a solution of salt and water? Explain your answer.

Section 3: Particles in Solution Standard 3: Demonstrate an understanding of various properties and classifications of matter. Indicators: 3.1, 3.5 Objectives: Examine how some solutes break apart in water solutions to form positively and negatively charged particles. Determine how some solutions conduct electricity. Describe how antifreeze words.

Ions - particles with a charge Electrolytes - compounds that form charged particles (ions) and conduct electricity in water Nonelectrolytes - substances that do not ionize in water and cannot conduct electricity

An ionic solid separates into its positive and negative ions. How ions form Molecules break apart in water, causing atoms to become ions by taking on a charge. Example: Neutral Atoms → Ions Example: Ionic compound → Ions

All solute particles-polar, nonpolar, electrolyte, and nonelectrolyte-affect the physical properties of the solvent. Adding a solute to a solvent lowers the freezing point because the added solute particles interfere with the formation of the orderly freezing pattern. Adding a solute raises the boiling point because fewer solvent molecules can reach the surface and evaporate.

1. What kinds of substances will not come off in water alone? 2. How do detergents help clean clothes?

Nonpolar materials have no positive or negative areas. They are not attracted to the polar water molecules, so they do not dissolve easily in water. Example: oils contain hydrocarbons. a. Large molecules of carbon and hydrogen atoms b. These atoms share electrons in an equal manner, so there is not positive or negative charge.

Nonpolar solvents dissolve nonpolar solutes. Drawbacks of Nonpolar Solvents Many nonpolar solvents are toxic - dangerous to touch or inhale Like Dissolves Like

Soap - used for washing because it has polar and nonpolar properties.

B vitamins and vitamin C are polar-dissolve in the water in your body cells.

Vitamin A is nonpolar-dissolves in the fat of some body cells.