Praxis Chemistry: Content Knowledge Online Center
This Praxis Chemistry: Content Knowledge Online Center brings together practice, lessons, worksheets, flashcards and review tools. Choose the resource that matches the skill you want to work on next.
Praxis Chemistry Practice Center
Take a full 150-minute form with no calculator, then read the explanation under every question you missed. Half or more of the real test integrates a science and engineering practice, so a miss is often about experimental reasoning rather than about chemistry.
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Praxis Chemistry: Content Knowledge at a glance
The single most important fact about this test is that you do not get a calculator. ETS says you will not need one, and that is true, but only if you have practised chemistry arithmetic by hand. A candidate who has done every stoichiometry problem for three years on a calculator will find the first twenty questions slower than expected. The periodic table and a table of constants are on the Help screen, so looking up an atomic mass costs you nothing but a click.
| Test code | 5246 (Chemistry: Content Knowledge) |
|---|---|
| Status | Current. No retirement date or successor code is published. |
| Number of questions | 125 selected-response questions. There is no constructed response. |
| Time limit | 2 hours 30 minutes |
| Calculator | Not provided. ETS states test takers will not need to use calculators. |
| Reference materials | A periodic table is provided on the Help screen, along with a table of physical constants and SI conversion factors. |
| Format | Computer-delivered |
| Score scale | 100 to 200 |
| Passing score | ETS does not set one. Each state sets its own qualifying score. |
| How it is asked | Half or more of the questions integrate a science and engineering practice, and roughly a quarter to a third assess a task of teaching science. |
ETS publishes counts and percentages for all five categories: Nature and Impact of Science and Engineering 17 questions and 14 percent, Principles and Models of Matter and Energy 31 and 25 percent, Chemical Composition Bonding and Structure 25 and 20 percent, Chemical Reactions and Periodicity 29 and 23 percent, and Solutions and Acid-Base Chemistry 23 and 18 percent. Note that thermodynamics and kinetics are not paired in this framework: thermodynamics sits in category II and kinetics in category IV. Bonding and periodicity are likewise split, bonding in III and periodicity in IV.
The five categories, in plain language
ETS lists each category and the topics under it. Here is what each one asks of you.
I. Nature and impact of science and engineering (14 percent, 17 questions)
Doing chemistry safely and interpreting what comes out.
- Science and engineering practices
- Experimental design and error analysis
- Measurement, significant figures, and units
- Data analysis and graphing
- Laboratory safety and handling reagents
- Science, technology, and society
II. Principles and models of matter and energy (25 percent, 31 questions)
The largest category: states, energy, rates, and the nucleus.
- States of matter, phase change, and heating curves
- The gas laws and kinetic molecular theory
- Thermochemistry, enthalpy, and Hess’s law
- Calorimetry
- Entropy and Gibbs free energy in outline
- Reaction kinetics, rate laws, and catalysis
- Nuclear chemistry and half-life
III. Chemical composition, bonding, and structure (20 percent, 25 questions)
What things are made of and how they hold together.
- Atomic structure, isotopes, and electron configuration
- Ionic, covalent, and metallic bonding
- Lewis structures and VSEPR geometry
- Polarity and intermolecular forces
- Naming and writing formulas
IV. Chemical reactions and periodicity (23 percent, 29 questions)
What happens when things react, and how the table predicts it.
- Balancing equations and reaction types
- Stoichiometry, limiting reagent, and percent yield
- The mole, empirical and molecular formulas
- Oxidation numbers, redox, and electrochemistry in outline
- Periodic trends
- Equilibrium and Le Chatelier’s principle
V. Solutions and acid-base chemistry (18 percent, 23 questions)
Chemistry in water.
- Solubility and concentration
- Molarity, dilution, and colligative properties
- Acid and base definitions
- pH, pOH, and strong against weak
- Titration and its curves
- Buffers, Ka and Kb in outline
A study routine for a no-calculator chemistry test
Two things need rebuilding for most candidates: hand arithmetic, and the parts of the framework that sit somewhere unexpected. Thermodynamics is not with kinetics here, and bonding is not with periodicity.
Complete topic map
Every topic ETS lists under the five categories, weighted the way the test is weighted.
Nature and impact of science and engineering (14 percent, about 17 questions)
- 01Recognize that scientific knowledge is developed through a variety of investigation methods rather than a single fixed method
- 02Recognize that scientific knowledge is based on experimental evidence that is reproducible
- 03Explain how major concepts develop and change over time in light of new evidence
- 04Form and test hypotheses
- 05Use models, laws and theories to explain natural phenomena, and develop and apply models for that purpose
- 06Apply process skills including observing, categorizing, comparing, generalizing, inferring and concluding
- 07Use standard units of measurement, dimensional analysis and unit conversion
- 08Use scientific notation and significant figures
- 09Design experiments, including identifying variables, planning data collection, and explaining how the design supports testing of the hypothesis
- 10Process, organize and report data
- 11Perform error analysis, including accuracy and precision, mean and percent error
- 12Identify the sources and effects of error
- 13Interpret and extrapolate from data and draw conclusions
- 14Prepare, use, store and dispose of laboratory materials appropriately
Principles and models of matter and energy (25 percent, about 31 questions)
- 15Describe the basic model of atomic structure, including the number and location of protons, neutrons and electrons
- 16Describe the quantum mechanical model of the atom, including orbitals and subatomic particles
- 17Explain the experimental basis of the atomic model, including the gold foil experiment and atomic spectra
- 18Write electron configurations using the Aufbau principle, Hund’s rule and the Pauli exclusion principle
- 19Correlate electron configuration with position on the periodic table
- 20Relate electron configuration to the chemical and physical properties of elements
- 21Explain electronic energy transitions in atoms
- 22Relate energy, frequency and wavelength of electromagnetic radiation
- 23Identify atoms based on analysis of spectra
- 24Correlate electronic transitions to spectral lines in the electromagnetic spectrum
- 25Describe the characteristics of alpha particles, beta particles and gamma radiation
- 26Explain radioactive decay, including the process, half-life and applications
- 27Identify fission and fusion reactions
- 28Balance nuclear reactions and identify the products of nuclear reactions
Chemical composition, bonding, and structure (20 percent, about 25 questions)
- 29Apply the mole concept, including Avogadro’s number, molar mass and mole conversions
- 30Calculate empirical and molecular formulas
- 31Calculate percent composition
- 32Write systematic names and chemical formulas for binary compounds
- 33Write systematic names and chemical formulas for acids, bases and salts
- 34Write systematic names and chemical formulas for hydrates
- 35Identify alkanes, alkenes and alkynes
- 36Identify common organic functional groups: alcohols, ethers, ketones, aldehydes, carboxylic acids and amines
- 37Describe and model ionic bonding
- 38Describe and model covalent bonding, including polar, nonpolar and hybridization
- 39Describe and model metallic bonding
- 40Compare relative bond strengths and bond lengths
- 41Draw Lewis structures, including formal charges
- 42Draw resonance structures
Chemical reactions and periodicity (23 percent, about 29 questions)
- 43Use the periodic table as a model, recognizing its arrangement in groups and periods
- 44Read element symbols, atomic number and atomic mass from the periodic table
- 45Locate metals, nonmetals, metalloids and transition elements on the periodic table
- 46Predict and justify trends in atomic and ionic radius based on position on the periodic table
- 47Predict and justify trends in ionization energy, electron affinity and electronegativity
- 48Predict and justify trends in physical properties and in chemical properties and reactivity
- 49Balance equations for simple chemical reactions
- 50Balance oxidation-reduction reactions
- 51Perform stoichiometric calculations based on balanced equations involving moles, mass or volume
- 52Perform limiting reagent calculations and calculate percent yield
- 53Predict the products of combustion, neutralization, synthesis, decomposition and dehydration reactions
- 54Predict the products of single and double replacement reactions
- 55Assign oxidation numbers
- 56Identify oxidation-reduction reactions and half-reactions
Solutions and acid-base chemistry (18 percent, about 23 questions)
- 57Classify solutions as dilute, concentrated, unsaturated, saturated or supersaturated
- 58Identify the solute and the solvent in a solution
- 59Represent concentration in various units such as molarity, mole fraction and percent by mass or volume
- 60Perform the calculations needed to prepare solutions of varying concentrations
- 61Analyze factors affecting the rate of dissolving, including temperature, pressure, surface area and stirring
- 62Interpret solubility and solubility curves, including temperature and pressure dependence
- 63Explain freezing point depression and boiling point elevation as colligative properties
- 64Explain the vapor pressure effect as a colligative property
- 65Distinguish highly soluble from slightly soluble compounds
- 66Predict precipitation based on the solubility product Ksp
- 67Apply the common ion effect when mixing ionic solutions
- 68Distinguish electrolytes from nonelectrolytes and relate them to the electrical conductivity of solutions
- 69Apply the Arrhenius model of acids and bases
- 70Apply the Bronsted-Lowry model of acids and bases
Before test day
Balance the equation before you do anything else with it. More points are lost on this test to stoichiometry built on an unbalanced equation than to any concept gap, and the answer you get from an unbalanced equation is usually sitting there in the choices. After that, watch the difference between a strong acid and a weak one, because half the pH questions turn on it.
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