Section 1Acids, Bases, and Salts

Section 1: Acids, Bases, and pH

Preview• Key Ideas• Bellringer• Acids• Bases• pH• Math Skills

Section 1Acids, Bases, and Salts

Key Ideas

〉What are the properties of acids?

〉What are the properties of bases?

〉How is pH related to the concentration of hydronium ions and hydroxide ions in solution?

Section 1Acids, Bases, and Salts

Bellringer

Even if you have not studied acids and bases before, you may already know something about them. To tap into this knowledge, identify whether the following are acids or bases. (Hint: Acids and bases have chemical properties that are very different.)1. Vinegar2. Baking soda 3. Soap 4. Orange juice5. Antacid tablets 6. Name one or two properties of acids.7. Name one or two properties of bases.

Section 1Acids, Bases, and Salts

SPS6 .d Compare and contrast the components and properties of acids and bases.

Section 1Acids, Bases, and Salts

SPS6.e Determine whether common household substances are acidic, basic, or neutral.

Section 1Acids, Bases, and Salts

EQ: What are the components, properties and some common examples of acids and bases?

Section 1Acids, Bases, and Salts

Acids

What are the properties of acids?

Section 1Acids, Bases, and Salts

9-1-1 Acids

Acids taste sour, cause indicators to change color, and conduct electric current.

Section 1Acids, Bases, and Salts

9-1-2 Acids

They are also corrosive and can damage materials, including your skin.

Section 1Acids, Bases, and Salts

9-1-3 Acids

• acid: any compound that increases the number of hydronium ions, H3O+, when dissolved in water

Section 1Acids, Bases, and Salts

9-1-4 Acids

• indicator: a compound that can reversibly change color depending on conditions such as pH

Section 1Acids, Bases, and Salts

9-1-5 Acids, continued

• Strong acids ionize completely.

Section 1Acids, Bases, and Salts

9-1-6 Acids, continued

Strong acids are strong electrolytes.

Section 1Acids, Bases, and Salts

9-1-7 Acids, continued

electrolyte: a substance that dissolves in water to give a solution that conducts an electric current

Section 1Acids, Bases, and Salts

9-1-8 Acids, continued

• Weak acids do not ionize completely.

Section 1Acids, Bases, and Salts

9-1-9 Acids, continued

Weak acids are weak electrolytes.

Section 1Acids, Bases, and Salts

9-1-10 Acids, continuedSome common acids

Section 1Acids, Bases, and Salts

Bases

What are the properties of bases?

Section 1Acids, Bases, and Salts

9-1-11 Bases〉Bases have a bitter taste, and solutions of bases feel slippery.

Section 1Acids, Bases, and Salts

9-1-12 Bases〉Solutions of bases also conduct electric current, cause indicators to change color, and can damage the skin.

Section 1Acids, Bases, and Salts

9-1-13 Bases

base: any compound that increases the number of hydroxide ions, OH–, when dissolved in water

Section 1Acids, Bases, and Salts

9-1-14 Bases, continued

• Strong bases are ionic compounds that contain a metal ion and a hydroxide ion.

Section 1Acids, Bases, and Salts

9-1-15 Bases, continued

example: NaOH, sodium hydroxide

NaOH Na+ + OH–

Section 1Acids, Bases, and Salts

9-1-16 Bases, continued• Some bases ionize in water to

form hydroxide ions.–example: ammonia, NH3

Section 1Acids, Bases, and Salts

9-1-17 Bases, continued

Ammonia is a weak base because it ionizes partially, creating a small amount of ions.

Section 1Acids, Bases, and Salts

9-1-18 Bases, continued

• Weak bases are weak electrolytes.

Section 1Acids, Bases, and Salts

9-1-19 Bases, continuedSome common bases

Section 1Acids, Bases, and Salts

pH

How is pH related to the concentration of hydronium ions and hydroxide ions in solution?

Section 1Acids, Bases, and Salts

9-1-20 pH

The pH of a solution indicates its concentration of H3O+ ions.

Section 1Acids, Bases, and Salts

9-1-21 pH

In solutions, the concentration of hydronium ions is related to the concentration of hydroxide ions, OH–.

Section 1Acids, Bases, and Salts

9-1-22 pH

The pH of a solution also indicates the concentration of OH– ions.

Section 1Acids, Bases, and Salts

9-1-23 pH, continued

• pH: a value that is used to express the acidity or basicity of a system

Section 1Acids, Bases, and Salts

9-1-24 pH, continued

• A pH value corresponds to the concentration of hydronium ions.

Section 1Acids, Bases, and Salts

9-1-25 pH, continued

Each whole number on the scale indicates a tenfold change in acidity.

Section 1Acids, Bases, and Salts

9-1-26 pH, continued

• A neutral solution, such as pure water, has a pH of 7.

Section 1Acids, Bases, and Salts

9-1-27 pH, continued

• An acidic solution has a pH of less than 7.

Section 1Acids, Bases, and Salts

9-1-28 pH, continued

• A basic solution has a pH of greater than 7.

Section 1Acids, Bases, and Salts

pH, continuedThe pH Scale

Section 1Acids, Bases, and Salts

9-1-29 pH, continued

• The pH is the negative of the power of 10 that is used to describe the concentration of H3O+ ions.

Section 1Acids, Bases, and Salts

9-1-30 pH, continued

example: The concentration of H3O+ of pure water is 1 × 10–7 M.•The pH of pure water is 7.

Section 1Acids, Bases, and Salts

9-1-31 pH, continued

• pH is a base 10 logarithmic scale so each increase of one on the scale is really an increase of 10 times.

Section 1Acids, Bases, and Salts

9-1-32 pH, continued

•pH is measured by chemical indicators that change colors at certain pH’s and with electronic pH meters.