Pearson International A Level Chemistry Core Practical 6: Prepare 2-chloro-2-methylpropane from an alcohol

This core practical is part of Pearson's practical-learning programme. The method below is one defensible implementation, not a confidential instruction sheet. Centres may adapt equipment while preserving the scientific purpose, controls, measurements and safety requirements.

Aim and scientific principle

Prepare an organic halogenoalkane, separate the organic phase and evaluate purification and yield.

Begin by translating the title into a testable question. Identify what is deliberately changed, what is measured directly, what is calculated and what must remain controlled. Predict a relationship only after naming the mechanism. A prediction without a reason is weak; a reason without measurable variables cannot guide a practical design.

Apparatus and setup

Use reaction flask, separating funnel, drying agent, distillation apparatus, thermometer, balance and measuring glassware. Select every measuring instrument by range and resolution, not by name alone. Draw a labelled scientific setup that shows the working geometry and exactly where readings are taken. Include a control or blank when it distinguishes the target effect from drift, contamination or background response.

Before collecting results, check zero readings, calibration, leaks, alignment or sterility as relevant. Record the instrument resolution beside the first raw-data table. If a digital device displays more digits than its underlying accuracy supports, do not treat every digit as equally certain.

Method

1. React measured 2-methylpropan-2-ol with the specified chloride reagent under controlled conditions.
2. Transfer to a separating funnel, vent safely and identify layers before retaining the product-containing phase.
3. Wash as directed, dry the organic layer and decant or filter from the drying agent.
4. Purify by distillation over the expected boiling range and calculate percentage yield.

Plan the analysis before starting. This reveals whether an additional measurement is needed for a derived quantity and prevents a completed experiment from lacking a mass, length, concentration, background or calibration value. A method should be detailed enough for another trained student to reproduce, while avoiding decorative steps that do not affect validity.

Variables and controls

• Independent variable: reaction or purification condition if the procedure is investigated.
• Dependent variable: product mass, volume, boiling range or yield.