Notes # 2 acids, bases and ph

pH: a measure of how acidic or basic a substance is. pH: solutions can be classified as an acid, a base or neutral based on their pH. pH is a physical property of matter. Physical properties are properties of solutions that can be observed without causing a chemical change.

Indicators are used to determine the pH of a solution. Determining pH Indicators are used to determine the pH of a solution. pH range in a solution is between 0 and 14 When acids and bases react with each other they form neutral solutions. This is called a neutralization reaction.

Acids/Acidic solutions Acids can be identified by their sour taste, for example lemon juice Reaction to metals, such as zinc and acid gives of gas Reaction with bases to form neutral pH solutions. Example: vinegar and baking soda Acids have a pH of less than 7.0 The lower the number the more acidic it is

Formulas for acids usually have Hydrogen as the first element. Examples: HCl: Hydrochloric acid or stomach acid H2 SO4: Sulfuric acid, an industrial acid

Bases have a bitter taste, such as unsweetened chocolate Base/Basic solutions Bases have a bitter taste, such as unsweetened chocolate They have a slippery feel like dish soap They react with acids to from neutral solutions, like Tums to settle an upset stomach Bases have a pH greater than 7.0 The closer to 14 the more basic

Formulas for Bases can be recognized by an OH ending. Examples NaOH: Sodium Hydroxide, drain cleaner Ca(OH)2: Calcium Hydroxide, lime fertilizer

Neutral/neutral solutions Neutral solutions are neither an acid or a base Neutral solutions have a pH of 7.0 Pure water is a neutral solution

pH of common substances

Blue litmus paper turns red in an acid Indicators Litmus paper: has special dye in it that changes color when in an acid or base Blue litmus paper turns red in an acid Red litmus paper turns blue in a base

Litmus paper: blue in base, red in acid

Phenolphthalein: is used to test for the presence of a base Indicators Phenolphthalein: is used to test for the presence of a base It is colorless by itself and turns magenta in a base, and stays colorless in acidic or neutral solutions

Phenolphthalein: turns bright pink in a base

pH paper: has a range of colors depending on the pH of the solution Indicator pH paper: has a range of colors depending on the pH of the solution The color of the paper is compared to the chart to determine pH

SAFETY DON’T TOUCH OR TASTE LABORATORY CHEMICALS UNLESS YOU HAVE BEEN TOLD THAT IT IS SAFE TO DO SO!