Acids, Bases, and pHUnit 7: Acids and Bases

What are Acids? Definition: Ionic compounds that produce hydrogen ions

(H+) when dissolved in water What are ionic compounds? Compounds that contain positive and negative ions Example: Hydrogen chloride (HCl) separates into positive

hydrogen ions (H+) and negative chloride ions (Cl-) when dissolved in water

Creates hydrochloric acid

Properties of Acids Acids have certain characteristic properties: They taste sour Can conduct electricity React with metals to form hydrogen gas

Uses of Acids Industry Nitric and Phosphoric Acids are used to make fertilizer Hydrochloric acid used to clean swimming pools, bricks,

and concrete Sulfuric acid is important in car batteries Human Body and Foods Carboxylic acid is an important part of the amino acids

that make up the proteins in your body Hydrochloric acid is found in your stomach and

important to digestion Citric acid is found in Alka-Seltzer and is a common

flavoring agent and preservative

What is a Base? Definition: Ionic compounds that produce negative

hydroxide ions (OH-) when dissolved in water Example: Sodium hydroxide (NaOH) produces negative hydroxide

ions (OH-) and positive sodium ions (Na+) when dissolved in water

Properties of Bases Bases have certain characteristic properties: Bitter taste Slippery feel Conduct electricity

Uses of Bases Industry/Home Sodium hydroxide is found in many cleaning

products Calcium hydroxide is found in concrete Aluminum hydroxide is found in deodorant

Detecting Acids and Bases Certain compounds, called indicators, change color when acids or bases come into contact with them

An example is litmus paper

Strengths of Acids and Bases The strength of and acid depends on how many hydrogen ions it produces when dissolved in water

Stronger acid = more hydrogen ions Weaker acid = fewer hydrogen ions

The strength of a base depends on how many hydroxide ions it produces when dissolved in water

Stronger base = more hydroxide ionsWeaker base = fewer hydroxide ions

pH Scale Definition: pH is the measure of acidity, or hydrogen ion (H+) concentration, of a

substance

Acidity is the concentration of hydrogen ions in a solution

Pure water, which is neutral, has a pH of 7

Lower pH value = higher H+ concentration = more acidic

Higher pH value = lower H+ concentration = more basic

pH Scale Strongest bases have pH close to 14

Strongest acids have pH close to 0

pH scale is based on powers of ten

Example: A solution with a pH of 8 is 10x more basic

than a solution with a pH of 7 (101)

A solution with a pH of 9 is 100x more basic than a solution with a pH of 7 (102)

Summary Complete your Cornell Notes Summary

Key Items: Acid/Base Definition Examples and uses of each pH scale and how it works