Acids and Bases Notes and Questions Ms. Haapala

Acids and Bases Standard 5 Acids, bases, and salts are three classes of compounds that form ions in water solutions. a. Students know the observable properties of acids, bases, and salt solutions. b. Students know acids are hydrogen-ion- donating and bases are hydrogen-ion- accepting substances.

What is an acid? What is a base? Talk to your neighbor and come up with some examples: AcidBase 1. ________________ 2. ________________

Common Acids Acids: Acids: 1.Milk (slightly acidic) 2.Lemon, orange, etc (citric acid) 3.Vinegar 4.Stomach acid (HCl) 5.Acid Rain 6.Carbon Dioxide

Common Bases Bases Bases 1.Soap 2.Blood 3.Antacids 4.Baking Soda 5.Ammonia 6.Egg Whites

Properties of Acids  Taste: sour  Acids react with metal to form hydrogen gas –Video: Hyperlink for drop on acid on a metal (see the gas formed) Hyperlink for drop on acid on a metal (see the gas formedHyperlink for drop on acid on a metal (see the gas formed  Acidic Solutions conduct electricity

Properties of Bases Taste: bitter Taste: bitter Slippery to the touch Slippery to the touch Bases and metals do NOT react (nothing happens) Bases and metals do NOT react (nothing happens) Basic Solutions conduct electricity Basic Solutions conduct electricity

Litmus Paper Litmus paper changes color to distinguish solutions of acids and bases. Litmus paper changes color to distinguish solutions of acids and bases. Acidic solution – contains more (H+) than (OH-) Acidic solution – contains more (H+) than (OH-) Basic solution – contains more (OH-) than (H+) Basic solution – contains more (OH-) than (H+)

Litmus Paper Aqueous solutions of acids cause blue litmus paper to turn pink. Aqueous solutions of acids cause blue litmus paper to turn pink. Aqueous solutions of bases cause red litmus paper to turn blue. Aqueous solutions of bases cause red litmus paper to turn blue.

Check for understanding Decide if each example is or describes a property of an acid or a base: Decide if each example is or describes a property of an acid or a base: –Milk –Turns blue litmus paper red –Orange Juice –Does NOT react with metals –Tastes bitter

Water: Neutral Pure water is neutral Pure water is neutral produces equal # of hydrogen ions (H+) and hydroxide ions (OH-). produces equal # of hydrogen ions (H+) and hydroxide ions (OH-). Video clip – properties of acids and bases

Acids and Bases Standard 5 Acids, bases, and salts are three classes of compounds that form ions in water solutions. Students know how to use the pH scale to characterize acid and base solutions. d. Students know how to use the pH scale to characterize acid and base solutions.

What is the pH scale? The pH scale is related to the concentration of H+ ions which determines how acidic or basic a solution is. The pH scale is related to the concentration of H+ ions which determines how acidic or basic a solution is. AcidicBelow 7 AcidicBelow 7 Neutral7 Neutral7 BasicAbove 7 BasicAbove 7

pH scale The pH of a solution is the negative logarithm of the hydrogen ion concentration: pH = - log [H+] The lower concentration of H+, the higher the pH (more basic) The lower concentration of H+, the higher the pH (more basic) The higher the concentration of H+, the lower the pH (more acidic) The higher the concentration of H+, the lower the pH (more acidic)

Check for understanding What type of a solution has a pH of 8? What type of a solution has a pH of 8? Does an acidic solution have a high or low concentration of H+ ions? Does an acidic solution have a high or low concentration of H+ ions? What is the pH of water? What does that make it? What is the pH of water? What does that make it?