Chapter 10 Section 2 (pgs. 286-291)
Acids and Bases
-Lemons have acid
-You can use the characteristics of a solution to determine if it is acidic or basic
Acids and Their Properties
-acid: any compound that increases the number of hydronium ions
-hydronium ions are formed from hydrogen atoms and water molecules H3o+
A. Acids have a Sour Flavor
-many acids are corrosive
-taste, touch or smell should never be used to identify an unknown chemical
B. Acids Change Colors of Indicators
-indicator: is a substance that changes color in the presence of an acid or base
-bromthymol blue and litmus paper are used by scientists as indicators
-when an acid is added to blue litmus paper, the color changes to red
C. Acids React with Metals
-some acids react with metals to make hydrogen gas
-zinc is an active metal, which can react with hydrochloric acids to make hydrogen gas and zinc
chloride
D. Acids Conduct Electric Current
-acids form ions in solutions
-car batteries are an example of how an acid can conduct an electric current
E. Uses of Acids
-used in many fields of industry and in homes
-sulfuric acid is the most widely used acid in industry
-hydrochloric acid is used to separate metals and used to keep algae out of swimming pools and
also aides in digestion
Bases and Their Properties
-base: any compound that increases the number of hydroxide ions OH-hydroxide ions give bases their properties
A. Bases Have a Bitter Flavor and a Slippery Feel
-properties include a bitter taste and slippery feel
-taste, touch or smell should NEVER be used to identify an unknown chemical
-like acids, bases are corrosive
B. Bases Change Colors of Indicators
-bases turn most indicators a different color than acids do
-bases turn the color of red litmus paper to blue
-bromthymol blue turns a darker color when it reacts with a base
C. Bases Conduct Electric Current
-a hydroxide ion is actually a hydrogen atom and an oxygen atom bonded together
-an extra electron gives the hydroxide ion a negative charge
D. Uses of Bases
-sodium hydroxide is a base used to make soap and paper
-magnesium hydroxide and aluminum hydroxide are used in antacids to treat heartburn
(antacids neutralizes acids in your stomach)
Section Review
1. Write an original definition for acid, base, indicator
Acid is a compound that increases the number of hydronium ions when dissolved in water. A
base is a compound that increases the number of hydroxide ions when dissolved in water. An
indicator is something that changes colors around an acid or a base.
2. What happens to red litmus paper when it touches a base?
Red litmus paper turns blue
3. Compare the properties of acids with the properties of bases.
Acids are sour, bases are bitter –bases feel slippery –acids have a higher melting point –Both
conduct electric currents –acids react with active metals –both change color of indicators
(acids=red bases=blue)
4. Complete the table with the color change that will happen when the substance is added to the
indicator.
Indicator Color
Substance
Color of bromthymol blue
Water
Lemon Juice
Water will not change the color of the indicator
Yellow
Soap
Dark blue
5. What ions are present in a solution of hydrochloric acid (HCl)?
Hydronium ions and chloride ions are present
6. A solution conducts electric current. Can you use this property of the solution to determine if
it is acidic or basic? Explain.
No, because both acids and bases conduct electric currents.