Description of the Examination
The Chemistry examination covers material that is usually taught in a one-year college course in general chemistry. Understanding of the structure and states of matter, reaction types, equations and stoichiometry, equilibrium, kinetics, thermodynamics, and descriptive and experimental chemistry is required, as is the ability to interpret and apply this material to new and unfamiliar problems. During this examination, an online scientific calculator function and a periodic table are available as part of the testing software.
The examination contains approximately 75 questions to be answered in 90 minutes. Some of these are pretest questions that will not be scored. Any time spent on tutorials and providing personal information is in addition to the actual testing time.
Knowledge and Skills Required
Questions on the Chemistry examination require candidates to demonstrate one or more of the following abilities.
- Recall - remember specific facts; demonstrate straightforward knowledge of information and familiarity with terminology
- Application - understand concepts and reformulate information into other equivalent terms; apply knowledge to unfamiliar and/or practical situations; use mathematics to solve chemistry problems
- Interpretation - infer and deduce from data available and integrate information to form conclusions; recognize unstated assumptions
The subject matter of the Chemistry examination is drawn from the following topics. The percentages next to the main topics indicate the approximate percentage of exam questions on that topic.
A scientific (nongraphing) calculator is integrated into the exam software, and it is available to students during the entire testing time. Students are expected to know how and when to make appropriate use of the calculator. The scientific calculator for the iBT versions of the CLEP exams, together with a brief video tutorial, is available to students as a free download for a 30-day trial period. Students and encouraged to download the calculator and become familiar with its functionality prior to taking the exam.
Students will find the online scientific calculator helpful in performing calculations (e.g, arithmetic, exponents, roots, logarithms).
The scientific calculator for the eCBT versions of the CLEP exams is available on the CLEP Sampler.
The eCBT and iBT versions of the scientific calculators look different, but both calculators have the necessary capabilities that students will use to help them answer questions on the exams.
Structure of Matter
Atomic theory and atomic structure
- Evidence for the atomic theory
- Atomic masses; determination by chemical and physical means
- Atomic number and mass number; isotopes and mass spectroscopy
- Electron energy levels: atomic spectra, quantum numbers, atomic orbitals
- Periodic relationships, including, for example, atomic radii, ionization energies, electron affinities, oxidation states
- Binding forces
- Types: covalent, ionic, metallic, macromolecular (or network), dispersion, hydrogen bonding
- Relationships to structure and to properties
- Polarity of bonds, electronegativities
- Geometry of molecules, ions, and coordination complexes: structural isomerism, dipole moments of molecules, relation of properties to structure
- Molecular models
- Valence bond theory; hybridization of orbitals, resonance, sigma and pi bonds
- Other models, for example, molecular orbital
- Nuclear chemistry: nuclear equations, half-lives, and radioactivity; chemical applications
States of Matter
- Laws of ideal gases; equations of state for an ideal gas
- Kinetic-molecular theory
- Interpretation of ideal gas laws on the basis of this theory
- The mole concept; Avogadro's number
- Dependence of kinetic energy of molecules on temperature: Boltzmann distribution
- Deviations from ideal gas laws
Liquids and solids
- Liquids and solids from the kineticmolecular viewpoint
- Phase diagrams of one-component systems
- Changes of state, critical phenomena
- Crystal structure
- Types of solutions and factors affecting solubility
- Methods of expressing concentration
- Colligative properties; for example, Raoult's law
- Effect of interionic attraction on colligative properties and solubility
Formation and cleavage of covalent bonds
- Acid-base reactions; concepts of Arrhenius, Brønsted-Lowry, and Lewis; amphoterism
- Reactions involving coordination complexes
- Oxidation number
- The role of the electron in oxidation-reduction
- Electrochemistry; electrolytic cells, standard half-cell potentials, prediction of the direction of redox reactions, effect of concentration changes
Equations and Stoichiometry
- Ionic and molecular species present in chemical systems; net-ionic equations
- Stoichiometry: mass and volume relations with emphasis on the mole concept
- Balancing of equations, including those for redox reactions
Concept of dynamic equilibrium, physical and chemical; LeChâtelier's principle; equilibrium constants
- Equilibrium constants for gaseous reactions in terms of both molar concentrations and partial pressure (Kc , Kp)
- Equilibrium constants for reactions in solutions
- Constants for acids and bases; pK; pH
- Solubility-product constants and their application to precipitation and the dissolution of slightly soluble compounds
- Constants for complex ions
- Common ion effect; buffers
- Concept of rate of reaction
- Order of reaction and rate constant: their determination from experimental data
- Effect of temperature change on rates
- Energy of activation; the role of catalysts
- The relationship between the rate-determining step and a mechanism
- First law: heat of formation; heat of reaction; change in enthalpy, Hess's law; heat capacity; heats of vaporization and fusion
- Second law: free energy of formation; free energy of reaction; dependence of change in free energy on enthalpy and entropy changes
- Relationship of change in free energy to equilibrium constants and electrode potentials
The accumulation of certain specific facts of chemistry is essential to enable students to comprehend the development of principles and concepts, to demonstrate applications of principles, to relate fact to theory and properties to structure, and to develop an understanding of systematic nomenclature that facilitates communication. The following areas are normally included on the examination:
- Chemical reactivity and products of chemical reactions
- Relationships in the periodic table: horizontal, vertical, and diagonal
- Chemistry of the main groups and transition elements, including typical examples of each
- Organic chemistry, including such topics as functional groups and isomerism (may be treated as a separate unit or as exemplary material in other areas, such as bonding)
Some experiments are based on laboratory experiments widely performed in general chemistry and ask about the equipment used, observations made, calculations performed, and interpretation of the results. The questions are designed to provide a measure of understanding of the basic tools of chemistry and their applications to simple chemical systems.
Want to get a feel for the tests? Try out sample questions from actual CLEP exams in the subject of your choice.
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