This document covers the acid and base
unit for GSMST Freshman Chemistry.
Study materials are provided for
personal use, and while I strive to make
sure that all information is 100%
accurate, I do make mistakes from time
to time. If you find an error in the
following text, please inform me via
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Studying for the
Acid and Base
Chemistry Test
A Complete Study Guide
Bryan G.
Properties of Acids and Bases
Acids taste sour and have a pH of less than 7; bases taste bitter and have a pH of greater
than 7. Both acids and bases can be tested by using litmus paper. If red litmus paper is dipped
into an acid, it remains red. If red litmus paper is dipped into a base, it turns blue. If blue litmus
paper is dipped into a base, it remains blue. If blue litmus paper is dipped into an acid, it turns
red. Acids neutralize bases and bases neutralize acids (pretty simple concept). Acids increase
the amount of H+ ions in a solution whereas bases increase the amount of OH- ions in a solution.
Acids can be called proton donators because they give away H+ ions, and bases can be called
proton acceptors because they take H+ ions. Both acids and bases can conduct electricity. Acids
react readily with metals and metal carbonates, and lastly, bases feel slippery.
Quiz Yourself!
Here’s how these quiz yourself things will work. I’ll write some questions and you should
answer them for practice. The answers will be at the end of this study guide.
Classify the following properties as either relating to bases or acids.
Feel slippery:
pH of 7 or lower:
pH of 7 or higher:
Turn litmus paper blue:
Turn litmus paper red:
Readily react with metals and metal carbonates:
Conducts electricity:
The Arrhenius Model
Svante Arrhenius stated that an acid is any substance that contains hydrogen and
ionizes to produce hydrogen ions in an aqueous solution. A base can be classified under this
model as any substance that contains a hydroxide group and dissociates to produce hydroxide
ions in an aqueous solution.
Quiz Yourself!
Classify the following chemical compounds as either Arrhenius acids or Arrhenius bases.
HF:
NaOH:
Ba(OH)2:
HCN:
KOH:
HCl:
The Bronsted-Lowry Model
Two scientists—Johannes Bronsted and Thomas Lowry—came along and redefined
acids and bases. Under their definition, an acid is simply anything that gives away a hydrogen
ion while a base is simply anything that accepts a hydrogen ion.
Self-Ionization of Water
Water is constantly breaking down into hydronium (H3O+) and hydroxide (OH-).
Therefore, water can be classified as both an acid and a base!
Quiz Yourself!
Write an equation for the self-ionization of water.
_____________________________________________________________________________________
Conjugate Acids and Bases
A conjugate acid is formed when a base accepts a hydrogen ion from an acid. A
conjugate base is formed when an acid gives a hydrogen ion away. Therefore, a conjugate acidbase pair consists of two substances that are related to each other because they donated and
accepted one hydrogen ion between the two of them.
View the following equation: HX(aq) + H2O(l) ↔ H3O+(aq) + X-(aq). HX is the acid
because it is capable of giving away its hydrogen ion. When the HX gives away its hydrogen
ion, a conjugate base called X- is formed. When the basic H2O receives the hydrogen ion that HX
gave away, it turns into the conjugate acid of H3O+.
Quiz Yourself!
Identify the acids, bases, conjugate acids, and conjugate bases in the following problems.
HF+H2O→F−+H3O+
HCN+H2O→H3O++CN−
Strong/Weak Acids and Bases
The following list of acids and bases (along with their strength) should be memorized!
Acid/Base
HCl
HBr
HI
HNO3
HClO4
H3PO4
H2SO4
HF
CH3COOH
H2CO3
Vitamin C
__OH
NH3
All Other Bases
Strength
Strong Acid
Strong Acid
Strong Acid
Strong Acid
Strong Acid
Strong Acid
Strong Acid
Weak Acid
Weak Acid
Weak Acid
Weak Acid
Strong Base
Weak Base
Weak Base
Quiz Yourself!
Visit the following Quizlet link and memorize these acids and bases!
http://quizlet.com/69158477/acids-and-bases-to-memorize-flash-cards/
pH Scale
The pH scale ranges from 0 to 14 where acids are ranked anywhere from a 0 to ~6.9
(anything less than 7) and bases are ranked anywhere from ~7.1 (anything greater than 7) to 14.
Right in the middle, at 7 pH, substances are considered neutral. At a pH of 0, there is 1M H+. At
a pH of 14, there is 10-14M H+. At a neutral pH of 7, the values of H+ and OH- are equal (10-7 M
each); this special value is called the Kw and is the equilibrium constant of water. Every change
in 1 on the pH scale represents a change by a factor of 10. Therefore, the concentration of H+ at
any point in the pH scale is equal to 10-pH (pH = -log (H+ concentration)). pH + pOH = 14.00.
Quiz Yourself!
Visit the following link to find 22 practice problems along with a pH problem solving
diagram.
http://www.sciencegeek.net/Chemistry/taters/Unit8pH.htm
Neutralization of Acids and Bases/Titration
When an acid and a base come in contact with each other, a reaction, called a
neutralization reaction, occurs. The reaction creates a salt and water. A salt is an ionic
compound that is the result of the basic cation and the acidic anion; therefore, the reaction is a
double displacement. For example, view the reaction between hydrochloric acid and
magnesium hydroxide: Mg(OH)2 (aq) + 2 HCl (aq)  MgCl2 (aq) + 2H2O (l). In the above
reaction, magnesium hydroxide is the base and hydrochloric acid is the acid. When they react,
the aqueous salt magnesium chloride is formed with a byproduct of water. The aqueous salt
(magnesium chloride) was formed from the basic cation and the acidic anion. The process and
concept of stoichiometry can be applied to these neutralization reactions too.
Stoichiometry is very useful to use in these scenarios because it provides a solid base for a
procedure named titration. Titration is a method to figure out the concentration of an unknown
solution by reacting a known volume of the unknown solution with a different solution of a
known concentration (called the titrant).
Quiz Yourself!
Visit the following link and practice a virtual titration lab; afterwards, solve for the
unknown molarity!
http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/stoichiometry/acid_base.html
If you are having troubles solving these problems, view this Khan Academy series:
https://www.khanacademy.org/science/chemistry/acid-base-equilibrium/new-topic-2015-0125T14:45:45.983Z
Answer Key
Classify the following properties as either relating to bases or acids.
Feel slippery: BASE
pH of 7 or lower: ACID
pH of 7 or higher: BASE
Turn litmus paper blue: BASE
Turn litmus paper red: ACID
Readily react with metals and metal carbonates: ACID
Conducts electricity: ACIDS AND BASES
Classify the following chemical compounds as either Arrhenius acids or Arrhenius bases.
HF: ARRHENIUS ACID
NaOH: ARRHENIUS BASE
Ba(OH)2: ARRHENIUS BASE
HCN: ARRHENIUS ACID
KOH: ARRHENIUS BASE
HCl: ARRHENIUS ACID
Identify the acids, bases, conjugate acids, and conjugate bases in the following problems.
HF+H2O→F−+H3O+
ACID: HF
BASE: H2O
CONJUGATE ACID: H3O+
CONJUGATE BASE: FHCN+H2O→H3O++CN−
ACID: HCN
BASE: H2O
CONJUGATE ACID: H3O+
CONJUGATE BASE: CN