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Credit Sprint's Guide to Descriptive and Experimental Chemistry for CLEP® Chemistry

CLEP® Chemistry asks more about what substances look like and do, and about lab technique, than AP® Chemistry does. Expect questions on colors of ions, precipitates, gases and flame tests, the properties of the main groups, and standard laboratory procedures.

What you need to know

• Colors: Cu²⁺ is blue, MnO₄⁻ purple, Fe³⁺ yellow-brown, Ni²⁺ green, Cr₂O₇²⁻ orange. Most main-group ions are colorless.
• Common precipitates: AgCl is white, AgI yellow, PbI₂ yellow, Cu(OH)₂ blue, Fe(OH)₃ red-brown, BaSO₄ white.
• Gases: H₂ burns with a pop, O₂ relights a glowing splint, CO₂ turns limewater cloudy, NH₃ has a sharp smell and turns damp red litmus blue.
• Alkali metals react vigorously with water to give H₂ and a basic solution. Halogens get less reactive down the group: Cl₂ oxidizes Br⁻ and I⁻.
• Flame tests: Na gives yellow, K lilac, Li red, Cu blue-green, Ca orange-red.
• Lab technique: read a buret to 0.01 mL, titrate until the indicator changes, heat a hydrate to constant mass, and use a pipet for accurate volumes.
• Separation methods: filtration for solid–liquid, distillation for liquids with different boiling points, chromatography by polarity.
• Safety: add acid to water, wear goggles, use a fume hood for toxic gases.

Practice questions