Mixtures Water pH Honors Biology

Mixture: A combination of two or more substances that are physically mixed They are not chemically combined!! Examples: soil, salsa, trail mix, milk & cereal, sugar water.

Types of Mixtures: A. Solution : A mixture formed when one substance dissolves in another- molecules are evenly distributed.

1. Solute: the substance that is dissolved in a solution 2. Solvent: the substance that does the dissolving. Example: salt water solute=salt, solvent=water Parts of a Solution :

1. Solute: the substance that is dissolved in a solution 2. Solvent: the substance that does the dissolving. Parts of a Solution :

B. Suspension: Mixture of water and non-dissolved materials (In between a Mixture and Solution) A Colloid: A suspension where you can’t see materials with naked eye  Examples: Blood, Milk

Now test what you learned: Indicate whether each is a mixture, solution or suspension. Unknown #1: Mixture Salt & Pepper

Unknown #2: Saltwater: Solution Solute: Solvent: Water Salt

Unknown #3: Solution Solute: Solvent: Sugar Lemon Juice

Unknown #4: Suspension Muddy Water

Unknown #5: Solution Solute: Solvent: Chocolate Milk

Unknown #6: Solution Solute: Solvent: Kool-Aid Water Kool-Aid

Special Type of Solution Emulsion – a type of Colloid An emulsion is a suspension of two liquids that usually do not mix together. For example if we mix oil and water a suspension will form that over time separates. But now, if we add a few drops of a third substance, the emulsifier, and shake the mixture the oil and water will stay mixed much longer. Examples of emulsions include butter and margarine, and mayonnaise.

Water: Needed for Life Water has several properties that make it necessary for life. It is POLAR - It has area with a slight positive charge, and an area with a slight negative charge.

Water: Needed for Life This polarity gives us the property of Hydrogen Bonding.

Water: Needed for Life Hydrogen Bonding allows one water molecule to “stick” to another water molecule.

Water: Cohesion Cohesion is the ability for water molecules to stick to themselves Beads of Water Surface Tension

Water: Adhesion Adhesion is the ability for water molecules to stick to other materials Meniscus in a graduated cylinder

Water: A Great Solvent Remember… A solvent has the ability to dissolve other materials Water is a solvent for many things For example: The liquid part of your blood (the plasma) is 90% water Some items, such as fats and oils DO NOT dissolve in water.

pH: What is it? The pH scale is used to measure the strength of acids and bases

pH: What is it? Some compounds break up into ions when they dissolve in water. Solutions with more H+ ions are more ACIDIC They have a LOW pH (<7) Solutions with less H+ ions are more BASIC They have a HIGH pH (>7) H2O H+ + OH-  

pH: What is it? Some properties of acids and bases pHExample Characteristics Acids Neutral Bases < 7 = 7 > 7 Lemon vinegar soda, aspirin Sour, burns, dissolves things Pure Water Soap, baking soda, ammonia Bitter, Slippery

pH: Looking at common items Battery Acid pH = 0 Orange Juice pH = 3 Ocean Water pH = 8 Oven Cleaner pH = 13

pH: Importance to Humans Blood has a pH of 7.4 (about neutral) If pH goes below 6.8 or above 7.8 it is deadly! To keep blood at the proper pH - our body uses buffers

pH: Buffers Buffers are weak acids or bases that neutralize, or weaken, strong acids or bases. In blood, buffers prevent pH change. Sodium bicarbonate, or baking soda, is a buffer