Unit 6—Interactions of Matter Chapter 22---Solutions Physical Science Unit 6—Interactions of Matter Chapter 22---Solutions Note: You will not be able to view the videos from the internet version of this presentation. Copyright laws prevent that option. Introductory Video 1 1

22-1 How Solutions Form Solution—a mixture that appears the same throughout and is mixed at the molecular level. Solute --substance being dissolved. Solvent –substance doing the dissolving. 2

3. Solutions can be liquids, gases, or solids. 4. Alloys are solid solutions. Video—Alloys :31 3

How dissolving happens: 22-1 How Solutions Form How dissolving happens: 1. Water molecules are polar—they have a positive area and a negative area. Video—Polar Molecules :45 4

Water molecules pull the solid particles into solution. 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. 5

22-1 How Solutions Form The moving water molecules and solid molecules spread out and mix evenly to form a solution. To mix solids to make an alloy solution, you must melt the solid. 6

Rate of dissolving depends on: 22-1 How Solutions Form Rate of dissolving depends on: 1. Stirring—speeds up dissolving by bringing more fresh solvent into contact with more solute. 7

a. Dissolving occurs at the surface of a solid 2. Crystal size a. Dissolving occurs at the surface of a solid b. Breaking a solid into pieces or powder increases its surface area, which speeds up dissolving. 8

22-1 How Solutions Form To make a gas dissolve more quickly in a liquid, cool the liquid solvent and increase the pressure of the gas. Video Temp., pressure, Other Factors 1.59 9

22-2 Dissolving Without Water Non-polar materials have no positive or negative area. They are not attracted to the polar water molecules, so they do not dissolve easily in water. Video Non-Polar Molecules 1.49 10

Example: oils contain hydrocarbons. Large molecules of carbon and hydrogen These atoms share electrons in an equal manner, so there is not positive or negative charge. 11

22-2 Dissolving Without Water Useful non-polar molecules Non-polar solvents dissolve non-polar solutes. Many non-polar solvents are toxic—dangerous to touch or inhale. Soap—used for washing because it has polar and non-polar properties. 12

22-2 Dissolving Without Water Polarity and Vitamins B vitamins and vitamin C are polar—dissolve in the water in your body cells. Vitamin A is non-polar –dissolves in the fat of some body cells. 13

22-3 Solubility and Concentration Solubility—the amount of a substance that can dissolve in a solvent Depends on the nature of the substance The solubility of two substances can be compared by measuring. 14

22-3 Solubility and Concentration 1. A concentrated solution has a large amount of solute in the solvent 15

22-3 Solubility and Concentration 2. A dilute solution has a small amount of solute in the solvent. 3. Concentrations can be expressed as percent by volume of the solute. 15

22-3 Solubility and Concentration Types of solutions. Saturated solutions —contains all the solute it can hold at a given temperature. 17

22-3 Solubility and Concentration 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. 18

22-3 Solubility and Concentration Unsaturated solution —able to dissolve more solute at a given temperature. Supersaturated solution —contains more solute than a saturated one at the same temperature 19

Super-saturated solution is made by raising temperature of a saturated solution, adding more solute, and lowering temperature back without disturbing the solution. Video-Saturated-Supersaturated 1:22 Video-Temperature, etc. 1:59 20

b. Unstable– will crystallize if disturbed. c b. Unstable– will crystallize if disturbed. c. As it crystallizes, it gives off energy and produces heat. 21

22-4 Particles in Solution Ions —particles with a charge Electrolytes—compounds that form charged particles (ions) and conduct electricity in water. Non-electrolytes—substances that do not ionize in water and cannot conduct electricity Video—Ions 1.48 22

22-4 Particles in Solution How ions form Ionization –molecules break apart in water, causing atoms to become ions by taking on a charge. Dissociation —an ionic solid separates into its positive and negative ions. 23

22-4 Particles in Solution Effects of solute particles All solute particles—polar, non-polar, electrolyte, and non-electrolyte—affect the physical properties of the solvent. 24

Adding a solute to a solvent lowers the freezing point because the added solute particles interfere with the formation of the orderly freezing pattern. 25

Adding a solute raises the boiling point because fewer solvent molecules can reach the surface and evaporate. 26

Review for the Test over Chapter 22 All Homework will be due _______.

Sometimes, but not always REVIEW Will increasing the temperature increase the solubility of a solute in a solvent? Sometimes, but not always

Will the type of solution depend on the state of the solute? REVIEW Will the type of solution depend on the state of the solute? No

Are the particles of a a liquid moving? REVIEW Are the particles of a a liquid moving? Yes, constantly.

REVIEW When water dissolves sugar, are the positive ends of the water molecules attracted to the negative ends of the sugar molecules? No.

Which particles move more freely: solid, liquid or gas? REVIEW Which particles move more freely: solid, liquid or gas? Gas. Solids move less freely.

REVIEW True or false: The dissolving process for solid solutions occurs in the solid state. False

Will salad oil dissolve in vinegar? REVIEW Will salad oil dissolve in vinegar? No

REVIEW Oil-based paints, nail polish and iodine are examples of _______ solutions. Non-polar

Water can be used to dissolve _______ molecules. REVIEW Water can be used to dissolve _______ molecules. polar

Explain why Vitamin C is polar. REVIEW Explain why Vitamin C is polar. Vitamin C has several oxygen-to-hydrogen bonds resembling those found in water.

Does a non-polar material have separated positive and negative areas? REVIEW Does a non-polar material have separated positive and negative areas? No

REVIEW Describe the sharing of electrons by hydrogen and carbons in hydrocarbons. They share electrons nearly equally.

Explain how to express the concentration of a solution to solute. REVIEW Explain how to express the concentration of a solution to solute. Express in terms of percentage by volume of the solute.

REVIEW If a drink has 10% fruit juice does this mean that it is 100% by volume of the drink? No, it is only 1/10 fruit juice.

REVIEW What is a solute? The substance being dissolved.

REVIEW A _______ does not conduct an electric current when it forms a solution. A non-electrolyte.

REVIEW A soltion that contains all of the solute it can hold at a given temperature is ____. Saturated

REVIEW The process by which the positive and negative ions of a crystalline solid separate in water is called _______. dissociation

Increasing the surface area of a solid will ____ the rate of solution. REVIEW Increasing the surface area of a solid will ____ the rate of solution. speed

REVIEW When a gas is dissolved in a liquid, the gas dissolves faster if the liquid is _____. Cooled.

REVIEW The concentration of a solution that contains a large amount of solute in the solvent could be described as ____. concentrated

An alloy is an example of a ____ solution. REVIEW An alloy is an example of a ____ solution. solid

Adding more solute to a solvent increases its ______. REVIEW Adding more solute to a solvent increases its ______. Boiling point

REVIEW A molecule that is positively charged on one end and negatively charged on the other end is ____. Polar.

REVIEW The amount of solute that can be dissolved in a specific amount of solvent at a given temperature is its ______. solubility.

REVIEW If we increase the pressure and decrease the temperature we would ____ the solubility of a gas in a liquid. increase

REVIEW Stirring the solution will ____ the speed of dissolving of the solid in water. increase