Chapter 22
Acids, bases and salts
1. Acids and Bases
a. Properties of acids
i. Produce hydrogen ions (H+) in a water solution
ii. Taste sour
iii. Corrosive
iv. Some acids can damage tissue by producing painful burns
v. Change blue litmus paper red
b. Common acids
i. Foods contain acids.
1. Citrus fruits have citric acid.
2. Yogurt and buttermilk have lactic acid
3. Vinegar or acetic acid, is a pickled food.
4. The stomach uses hydrochloric acid.
ii. Four acids are vital to industry:
1. Sulfuric acid (H2SO4) is used in car batteries and the manufacturing of
fertilizers.
2. Phosphoric acid (H3PO4) is used to manufacture detergents, fertilizers,
and soft drinks.
3. Nitric acid (HNO3) is used to make fertilizers
4. Hydrochloric acid (HCl) is used to clean steel
c. Bases- A substance that forms hydroxide ions in a water solution; also accepts hydrogen
ions from acids.
i. Properties of bases
1. Many are crystalline solids in a pure undissolved state.
2. Taste bitter
3. Feel slippery in solution.
4. Strong bases are corrosive and can cause severe burns.
5. React with indicators to produce predicable color changes; litmus paper
turns blue.
ii. Common bases are used in cleaning products, medications, fabrics, and
deodorants.
d. Solutions of acids and bases
i. Acid describes compounds that can be dissolved in water to form hydronium
ions.
ii. Base describes compounds that form hydroxide ions in a solution.
iii. Solutions of acid and solutions of bases are conductors to some extent.
2. Strength of acids and bases
a. The strength of an acid or base depends on how completely a compound separates into
ions when dissolved in water.
i. A strong acid ionizes almost completely into a solution.
ii. A weak acid only partially ionizes in solution.
iii. A strong base dissociates completely in solution.
iv. A weak base does not dissociate completely in a solution.
v. Strong acids and bases conduct more electricity than weak ones.
vi. Equations for strong acids and bases use a single arrow, indicating ions are
formed.
vii. Equations for weak acids and bases use double arrows pointing in opposite
directions indicating an incomplete reaction.
viii. Strength and concentration are terms to describe the amount of acid or base
dissolved.
b. pH of a solution
i. pH is a measure of the concentration of H+ in a solution or how acidic or basic it
is.
1. pH lower than 7 means acidic
2. pH greater than 7 means basic
3. pH exactly 7 means a neutral solution.
c. pH is determined using a universal indicator paper or a pH meter.
d. Blood contains buffers which keep the pH in the blood balanced at about 7.4.
3. Salts
a. Neutralization- chemical reaction between an acid and a base taking place in a water
solution.
b. Salt - Compound formed when the negative ions from an acid base combines with
positive ins from a base; salts also form when acids react with metals.
i. Salts are essential for many animals.
ii. Other salt uses include manufacturing of paint, rubber, glass, soap, detergents,
and dry blood cells.
c. Titration is used to determine the concentration of an acidic or basic solution.
i. A solution of a known concentration is the standard solution.
ii. An acid/base indicator is added to the unknown solution.
iii. A color change that persists is an end point.
d. Soaps are organic salts with polar and nonpolar ends.
i. The nonpolar, hydrocarbon end interacts with oil and dirt.
ii. The polar end helps oil and dirt dissolve in water.
e. Detergents- form more soluble salts with ions in hard water and reduce soap scum.
Chapter 22 Vocabulary
Acid - Substance that produces hydrogen ions, (H+), in a water solution
Base - A substance that produces hydroxide ions, OH–, in a water solution
Buffer - Solution that resists changes in pH when limited amounts of acid or base are added
Hydronium ion - H3O+ ion, forms when an acid dissolves in water and H+ ions interact with water
Hydroxide ion - OH– ion, forms when a base dissolves in water
Indicator - Organic compound that changes color in acids and bases
Neutralization - chemical reaction that occurs when the H3O+ ions from an acid react with the OH– ions
from a base to produce water molecules and a salt
PH - a measure of the concentration of hydronium ions in a solution using a scale ranging from 0 to 14,
with 0 being the most acidic and 14 being the most basic
Salt - Compound formed when negative ions from an acid combine with positive ions from a base
Soap - Organic salt with a nonpolar, hydrocarbon end that interacts with oils and dirt and a polar end that
causes it to dissolve in water
Strong acid - Any acid that dissociates almost completely in solution
Strong base - Any base that dissociates completely in solution
Titration - Process in which a solution of known concentration is used to determine the concentration of
another solution
Weak acid - Any acid that only partly dissociates in solution
Weak base - Any base that does not dissociate completely in solution