1. Describing Acids and Bases Acids & Bases in Solution
Chapter 7, Section 3 & 4
Describing Acids and Bases
Acids & Bases in Solution

2. Properties of Acids Taste sour React with metals and carbonates
Turn blue litmus paper red
Some common acids:
Hydrochloric acid
Nitric acid
Sulfuric acid
Carbonic acid
Acetic acid
Table Talk: Can you think of some other foods that are acidic based on their sour taste?
DO NOT RANDOMLY TASTE CHEMICALS!

3. Acids React With Metals Acids React With Carbonates
Acids react with magnesium, zinc, and iron to produce hydrogen gas
Corrosive = they wear away other materials
Carbonate ion = CO32-
CO2 gas is formed
Hydrochloric acid on limestone

4. Acids React With Indicators How Acids are Commonly Used
Litmus paper, made from a dye found in lichens, turns red in an acid, blue in a base
Many of the vitamins in foods you eat are acids
Ascorbic acid = vitamin C
Folic acid is in leafy green vegetables
Nitric acid and phosphoric acid are used to make fertilizers
Sulfuric acid is in batteries
Muriatic acid helps clean swimming pools

5. Table Talk: summarize the properties and uses of acids

6. Properties of Bases Common Uses of Bases
Taste bitter
Feel slippery
Turn red litmus paper blue
Some common bases:
Sodium hydroxide
Calcium hydroxide
Ammonia
In cement
Cleaning solutions
In baking (baking soda)

7. Solutions
Solution = A uniform mixture that contains a solvent and a solute
Solvent = the part of the solution present in the largest amount; it dissolves the other substance
Solute = the substance that is present in a solution in the smaller amount; it gets dissolved by the solvent

8. Acids in Solution Bases in Solution
Acids in water solution separate into hydrogen ions (H+) and negative ions
Example:
HCl  H+ + Cl-
Most bases are made of positive ions combined with hydroxide ions
When bases dissolve in water, the positive ions and the hyroxide ions separate
NH3 + H2O NH4+ + OH-

9. Strength of Acids & Bases
“Strength” refers to how well an acid or base produces ions in water Knowing the concentration of hydrogen ions is the key to knowing how acidic or basic a solution is This is measured with the pH scale, a range of values from 0-14, with 7 being “neutral” (neither acidic or basic)
The lower the pH, the more concentrated the ions are and the more acidic the solution is.
See BrainPop “pH Scale”

10. Table Talk: If you found that certain foods upset your stomach or gave you heartburn, what could you say about them? How could you ease that uncomfortable feeling?

11. Acid-Base Reactions
Neutralization = a reaction between an acid and a base
Example:
HCl + NaOH  H2O + Na+ + Cl-
After neutralization, a acid-base mixture is less acidic or basic than either of the individual starting solutions
This do-it-yourself volcano is actually an acid-base reaction between vinegar (an acid) and baking soda (a base). The foaming is the formation of CO2 gas.

12. Products of Acid-Base Reactions
To a chemist, salt = an ionic compound that can be made from the neutralization of an acid and a base
In a neutralization reaction, an acid reacts with a base to produce a salt and water:
HNO3 + KOH  H2O + K+ + NO3-
Table Talk: Potassium nitrate, KNO3, is a salt. Why is it split apart into ions in this equation?
Answer: because potassium nitrate is soluble in water.
What do you think would form if a salt was insoluble in water?
A precipitate!
See BrainPop “Acids & Bases” & “pH Scale”
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