Acids, Bases , & Solutions

Solutions Solution-uniform mixture that contains a solvent & solute Solvent-the part of the solution that is present in the largest amount Solute-the part of the solution that is present in the smaller amount and is dissolved… Water is the universal solvent, but solvents and solutes may be solids, liquids, or gases Solutions have the same properties throughout

Colloids a mixture that contains small undissolved particles, particles are too small to be seen, but large enough to scatter light

Suspension Does not have the same properties through out Contains visible particles

Effects of Solute & Solvents Solutes lower the freezing point & raise the boiling point of a solvent

Particles in Solution When a solution forms, particles of the solvent surround and separate the particles of the solute. Ionic and molecular compounds in solution Ionic – positive and negative ions are attracted to the polar water molecules. These types of compounds in water will conduct electricity. Molecular – breaks up into individual neutral molecules (sugar)

Common solutions Solute Solvent Solution Gas Air (oxygen and other gases in nitrogen) Liquid Soda water (carbon dioxide in water) Antifreeze (ethylene glycol in water) Solid Dental filling (silver in mercury) Ocean water (sodium chloride in water) Stainless steel (chromium, nickel, and carbon in iron)

Concentration Concentrated solution-lots of solute, little solvent Ex. Frozen juice Dilute solution-little solute, lots of solvent Ex. Frozen juice + water Measuring concentration-compare amount of solute to solvent Ex. 5 grams per 100mL

Solubility How much solute can dissolve in a solvent at a given temperature Unsaturated-can hold more solute Saturated-can NOT hold more solute Supersaturated-too much solute, some is undissolved at the bottom of the container

Factors affecting solubility Pressure Increasing the pressure increases the solubility and vise-versa Type of solvent Some solutes & solvents are incompatible Ex. Oil and vinegar The solvent affects the solubility of a substance Ex. Oil-based paint & water

Temperature Increasing the temp. of a solid increases the solubility Increasing temperature of a gas decreases the solubility

Acids and Bases Chemicals may be classified as acids or bases. Things that are neither acids nor bases are neutral. pH measures the acidicity or basidity of a solution

Acids Taste sour Turns blue litmus paper red Reacts with metals/carbonates Contains hydrogen ions H+ Examples: Lemon juice Vinegar Car battery acid (dangerous!)

Acids and Bases Some of our favorite foods make our tongue curl up because they are SOUR.

Bases Taste bitter Feel Slippery Turns red litmus paper blue Contains hydroxide ions OH- Turns Phenolphthalein pink Examples: Milk Baking soda Soap Drain cleaner (dangerous!)

Bitter! Some foods have a “bite” of their own because they’re somewhat bitter.

pH A special name given to the acid or base characteristic is called: pH

How Do We Measure pH? We measure pH by using special strips of paper called pH paper

How Does It Work? The paper is treated with chemicals that change color to show the pH. When the paper touches the substance being tested, it turns a specific color to tell if the substance is an acid or a base.

The pH Scale pH scale ranges from 0 -14 pH 7 is neutral; neither acid nor base Pure water is pH 7 Low pH = acid High pH = base The closer to the ends of the scale, the stronger the solution

0--------------7---------------14 Acid Any substance which has a pH value less than 7 is considered an acid 0--------------7---------------14 Acid Neutral Base

0--------------7---------------14 Base Any substance which has a pH value greater than 7 is a base 0--------------7---------------14 Acid Neutral Base

pH 7 A pH of 7 is called neutral—neither acid nor base. 0-------------7------------14 Acid Neutral Base

The pH Scale

The pH Scale Each pH unit is 10 times as large as the previous one A change of 2 pH units means 100 times more basic or acidic x10 x100

Acid-Base Reactions Neutralization-a reaction in which an acid reacts with a base to produce salt and water HCl + NaOH= H2O + NaCl