MIXTURES, EFFECTS OF SOLUTES ON SOLVENTS, CONCENTRATION & SOLUBILITY, ACIDS & BASES Chapter 7

Mixtures substances mixed together, but NOT chemically combined (think salad) Three Types of Mixtures:  Solutions  Colloids  Suspensions

Solution Smallest particles Same properties throughout Examples: kool-aid, salt water

2 Parts of a Solution Solvent: largest part, dissolves the solute, and can be a solid, liquid, or gas Water is the “Universal Solvent” This is because it is the most commonly used solvent Solute: smallest part, too small to be seen in solution, dissolved by the solvent

Colloids Particles are larger than those in a solution Small, undissolved particles that do not settle to the bottom Examples: fog, milk, mayonnaise Tyndall Effect: When a the particles in a colloid scatter light that is shown through it

Suspension  Has the largest particles  particles can easily be seen and easily separated  do not have the same properties throughout  Examples: sand in water, cereal, soup

FACTORS EFFECTING SOLUTIONS Chapter 7

Concentration the amount of one material in a certain volume of another material dilute: small amount of solute (sap) concentrated: very large amount of solute (syrup) can change the concentration 2 ways  add more solute  add or remove solvent

Solubility Ability of one substance to dissolve in another at a given temperature. It is expressed in terms of the amount of solute that will dissolve in a given amount of solvent to produce a saturated solution Insolubility is the inability of one substance to dissolve in another substance

Solubility Saturated Solution: solution that contains the maximum amount of dissolved solute Unsaturated solution: substance that contains less solute than a saturated solution under the same conditions Supersaturated solution: solution that contains more dissolved solute than a saturated solution under the same conditions

Factors that affect Solubility  Temperature  The higher the temperature, the more soluble the solute sugar in tea  Pressure  If the pressure of a gas solute is higher, more of the solute can be dissolved in the solvent Ex: CO2 in soda  Agitation  Stirring or shaking will cause the solute to dissolve more rapidly  Surface Area  The greater the surface area, the more rapidly the solute can dissolve  Type of Material  Polar and ionic compounds dissolve in water because water is polar and attracts the charges  Non-polar compounds dissolve non-polar substances

Solubility Curves Solubility curves show how much solute can dissolve in a solvent at a given temperature. Above the line is supersaturated On the line is saturated Below the line is unsaturated

Solubility Curve Practice What is the solubility of KNO 3 at 55 O C? A solution is prepared by adding 50 grams of KNO 3 to 100 ml of water at 50 O C. Is this solution saturated, unsaturated supersaturated? A solution is prepared by adding 50 grams of KNO 3 to 100 ml of water at 30 O C. Is this solution saturated, unsaturated, or supersaturated?

OSMOSIS & DIFFUSION Chapter 7

Diffusion The movement of particles from a more concentrated area to a less concentrated area. If you place a drop of food coloring in water and do not stir, the coloring will diffuse throughout the beaker and make the concentration equal throughout.

Osmosis The diffusion of water through a semi- permeable membrane.  A semi-permeable membrane allows some molecules to pass through, but not others.  The cells in our bodies are semi-permeable. H2OH2O Salt

3 Types of Solutions There are 3 types of solutions where we can have diffusion occur. To show these we will make a foldable. Steps 1. Take your piece of paper and fold it hot dog style. 2. Fold your piece of paper into thirds. When you open it up, you should see three equal sections. 3. Using your scissors, cut the paper along the fold lines you made in step 2.

Solution 1 On the front of your foldable draw and label the picture to the right: On the top inside write:  There is more H2O and less solute outside the cell than inside, therefore, H2O flows in and the cell will swell On the bottom inside write:  Hypotonic Solution

Solution 2 On the front of your foldable draw and label the picture to the right: On the top inside write: The outside of the cell has more solute and less water than inside, therefore, H2O flows out and the cell will shrink. On the bottom inside write: Hypertonic Solution

Solution 3 On the front of your foldable draw and label the picture to the right: On the top inside write: The amount of water and solute inside the cell is equal to outside, therefore, H2O flows in both directions. On the bottom inside write: Isotonic Solution

ACIDS & BASES Chapter 7

What is an acid? An acid is a solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour". The more H + ions, the more acidic the solution.

Properties of an Acid Tastes Sour Conduct Electricity Corrosive: they “eat away” or break down certain substances.  Many acids can corrode fabric, skin,and paper Some acids react strongly with metals Turns blue litmus paper red Picture from BBC Revision Bites _bases_1.shtml _bases_1.shtml

Uses of Acids Acetic Acid = Vinegar Citric Acid = lemons, limes, & oranges. It is in many sour candies such as lemonhead & sour patch. Ascorbic acid = Vitamin C which your body needs to function. Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics. Car batteries

What is a base? A base is a solution that has an excess of OH- ions. Another word for base is alkali.

Properties of a Base Feel Slippery Taste Bitter Corrosive Can conduct electricity. (Think alkaline batteries.) Do not react with metals. Turns red litmus paper blue.

Uses of Bases Bases give soaps, ammonia, and many other cleaning products some of their useful properties. The OH- ions interact strongly with certain substances, such as dirt and grease. Chalk and oven cleaner are examples of familiar products that contain bases. Your blood is a basic solution.

Acids and Bases in Solution With water produce a hydrogen ion (H+) and a negative ion HCl in H2O  H+ + Cl- Bases With water produce a hydroxide ion (OH-) and a positive ion NaOH in water  Na+ + OH- Acids

NEUTRALIZATION & PH Chapter 7

Strength of Acids and Bases This refers to how well an acid or base produces ions in water. A strong acid will produce more H+ ions than a weak acid.  Strong acids: HCl, sulfuric acid, nitric acid  Weak acids: acetic acid (vinegar) A strong base will produce more OH- ions than a weak base.  Strong base: NaOH  Weak base: NH3 (ammonia)

Neutralization A reaction between an acid and a base is called neutralization. Sometimes the results are a neutral product, but not always. Salt: an ionic compound made from the neutralization of an acid with a base  + ion from the base and – ion from the acid  NaOH + HCl  H2O + NaCl  Salt and water are the products!

Salt Each salt listed in this table can be formed by the reaction between an acid and a base.

pH Scale pH is a measure of how much H+ ions there are. The pH scale ranges from 0 to 14. Acidic solutions have pH values below 7 A solution with a pH of 0 is very acidic. A solution with a pH of 7 is neutral. Pure water has a pH of 7. Basic solutions have pH values above 7.

pH Scale A change of 1 pH unit represents a tenfold change in the acidity of the solution. For example, if one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.