ACIDS AND BASESMrs. Brostrom

Integrated Science

Acids An acid is any compound that increases

the number of hydronium ions (H3O+) when dissolved in water The hydronium ion forms when a H ion (H+)

separates from the acid and bonds with a water molecule (H2O)

H3O+ → H+ + H2O

Properties of Acids A sour flavor

Lemons, limes, vinegar However, taste should never be used to

identify acids Some can be corrosive and poisonous

Change color in indicators A substance that changes color in the

presence of an acid or base is an indicator Litmus is a common indicator used to detect

the strength of acids When an acid is added to blue litmus paper, the

color changes to red• React with metals to produce hydrogen gas

Ex.) Hydrochloric acid reacts with zinc to produce hydrogen gas

2HCl + Zn → H2 + ZnCl2

Conduct electric current When acids dissolve in water, they break

apart and form ions Ex.) Car battery contains sulfuric acid

Uses of Acids Used in industry and homes

Sulfuric acid is most widely used industrial chemical; paper paint detergents, and fertilizers

Nitric acid; fertilizers, rubber, and plastics Hydrochloric acid is used to make metals from

their ores (by separating them), swimming pools, stomach

Hydrofluoric acid is used to etch glass Citric acid and ascorbic acid are found in

orange juice Carbonic acid and phosphorous acid are

found in soda

Bases A base is any compound that increases

the number of hydroxide ions (OH-) when dissolved in water Ex.) Sodium hydroxide breaks apart to form

sodium ions and hydroxide ions

NaOH → Na+ + OH-

Properties of Bases Bitter taste

Taste should never be used to identify a base, like acids they are corrosive

Slippery feel Ex.) Soap

Bases change colors in indicators Like acids, litmus is a common indicator used

to detect the strength of bases Bases change the color of red litmus paper to

blue Bases conduct electric current

Bases increase the number of hydroxide ions (OH-) which has a negative charge

Uses of Bases Sodium hydroxide, used to make soap,

paper, oven cleaners, drain cleaners Calcium hydroxide, used to make

cement and plaster Ammonia, found in many household

cleaners and used to make fertilizer Magnesium hydroxide and aluminum

hydroxide, used in antacids

SOLUTIONS OF ACIDS AND BASES

Mrs. BrostromIntegrated Science

Strengths of Acids Strength of acids and bases are not the same

as concentration As an acid dissolves in water, the molecules

break apart producing hydrogen ions (H+). If all the molecules break apart, the acid is called strong acid. Strong acids include sulfuric acid, nitric acid, and

hydrochloric acid• If only a few molecules break apart, it is

a weak acid. Weak acids include acetic acid, citric acid, and

carbonic acid

Strengths of Bases When all of the molecules of a base break

apart in water to produce hydroxide ions (OH-)the base is a strong base Sodium hydroxide, calcium hydroxide, and

potassium hydroxide • When only a few molecules break apart it is a weak base Ex.) Ammonium hydroxide and aluminum

hydroxide

Neutralization The reactions between acids and bases is

a neutralization reaction The hydrogen ions (H+) that are present

in an acid and the hydroxide ions (OH-) that are present in a base react to form water

H+ + OH- → H2O• The other ions in the acids and base dissolve in the water and if it evaporates, bond together to produce salt

For Example…

The pH Scale The pH of a solution

is a measure of the hydronium ion concentration in a solution pH of 7 is neutral

(neither acid or base); pure water

Basic solutions have a pH greater than 7

Acidic solutions have a pH less than 7

Measuring pH pH can be measured using

pH (litmus) paper pH meter

• Living things depend on having a steady pH- lettuce needs basic soil; between 8 and 9

• Most rain has a pH between 5.5 and 6

Salts When an acid neutralizes a base, water

and salt is produced A salt is an ionic compound formed from

the positive ion of a base and the negative ion of an acid NaCl, used to season food Sodium nitrate, used to preserve food

HCl + NaOH → H2O + NaCl