Chapter 9 – Acids and Bases

BELLWORK

Pure vinegar is an acid, called ________ acid

• Key Questions:• 1] What are the properties of acids?• 2] What are the properties of bases?• 3] How is pH related to the concentration of

hydronium ions and hydroxide ions in solution?

• 4] What are some household products that contain acids, bases, and salts?

Chapter 9 – Acids and Bases

State Standards

• CLE.3202.1.10 – Distinguish among acids, bases, and neutral substances

• CLE.3202.Inq.2 – Recognize that science is a progressive endeavor that reevaluates and extends what is already accepted

Key Terms- Acid : Lose an H+ ion when ionized or dissolved in

water. Acids are corrosive, taste sour, conduct electricity, and turn indicators different colors

- Indicator : Compound that reversibly changes colors depending on pH

- Electrolyte : Substance that dissolves in water enabling solution to conduct electricity

Key Terms- Base : Lose OH- when ionized or dissolved in water. Bases

have bitter taste, and their solutions feel slippery. These solutions can also conduct electricity, turn indicators colors, and damage skin

- pH : Value used to describe the amount of acidity or basicity ( each whole number on a scale from 0-14 indicates a tenfold change in acidity )

- Salt : A compound that has a negative ion and a positive ion bonded together ( NaCl )

Water

• H2O H3O+ + OH-

• Balanced?

• Dissolves itself to form H3O+ and OH-

– Hydronium and Hydroxide

Everyday Acids• Citrus fruits, such as lemons, limes, and oranges,

contain citric acid. Apples contain malic acid; grapes contain tartaric acid.

• Acids increase amount of H3O+ when added to water (Acids lose H+ ions but water gains them!! )

Everyday Bases• Bases increase amount of OH- when

added to water– Bases may lose OH- but not always– As opposed to acids ( how? )

• Common household cleaners ( ammonia based )

Everyday Salts

• Salts are not acids & bases ( but similar )– They both can dissolve

when added to water• Common types: – Soap ( salts of Na or K and

long hydrocarbon chains– Detergents– Salt ( Duuhh!! )

Indicators

• Acids turn Blue Litmus paper Red

• Bases turn Red Litmus paper Blue

• Demonstration – What happened?– Vinegar– Lemon Juice– Sodium Hydroxide ( NaOH )– Milk of Magnesia– Tap water

pH

• pH values correspond to the amount of hydronium ions

Why It Matters

• Normal rain has a pH of about 5.6, so it is slightly acidic. Acid rain is a type of pollution in which the precipitation has a pH that is less than 5.0. Acid rain results from emissions of sulfur dioxide, SO2, and nitric oxide, NO, which are gases from coal-burning power plants and automobiles. The gases react with compounds in the air to form sulfuric acid, H2SO4, and nitric acid, HNO3.

Why It Matters

• Acid rain is a type of pollution that can have harmful effects on many parts of the environment, including animals, plants, and buildings

• Mercury ingestion – acid rain causes more organic mercury to form in lakes, streams, etc

• Organic mercury absorbs more easily in the human body!!

Chapter 9 – Acids and Bases

Key Questions:1] What are the properties of acids?2] What are the properties of bases?

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

4] What are some household products that contain acids, bases, and salts?