Edexcel IGCSE Chemistry CP1 Solubility Worksheet

A complete Edexcel International GCSE Chemistry (4CH1) Core Practical 1.7C worksheet: investigating the solubility of a solid in water at a specific temperature, with full mark scheme.

Two separate files

• Worksheet (12 pages): the student copy, print-ready in black and white
• Mark scheme (16 pages): the same worksheet completed with every answer written in red, with marks shown, plus teacher and technician notes, marking guidance and an Edexcel-style mark scheme for the exam questions

Use it during the practical, as a follow-up lesson or as homework. Students who miss the lab can still work through a full set of practice readings and a data-book solubility curve.

What students do

• Label a two-stage set-up: dissolving potassium chloride in a water bath at 40 °C, then filtering into an evaporating basin
• Explain why four steps matter (stirring, distilled water, weighing the basin and filtrate, a balance reading to 0.01 g)
• Follow the method for the solubility of potassium chloride at 40 °C, with three “why?” prompts
• Pick the correct way to dry and weigh the solid from three drawn set-ups, and explain the faults in the other two
• Put eight steps of the cooling method for potassium nitrate in order
• Read a thermometer and three balance displays
• Record their own results, or use the practice readings to calculate the mass of solid, the mass of water and the solubility in g per 100 g of water
• Plot a solubility curve for potassium nitrate and read values from it
• Work out the mass of crystals that form when a saturated solution cools
• Spot an anomalous repeat, calculate a mean and suggest a cause
• Decide how five mistakes affect the calculated solubility (too high, too low or no change)
• Answer 8 exam-style questions (21 marks) in the Edexcel style, including two multiple-choice questions, a solubility calculation, hydrated salts, solute and solvent, crystallisation, crystals on cooling and a 6-mark plan to investigate how the solubility of sodium nitrate changes with temperature

For teachers

• Quantities per group, timings over two lessons, the skills covered and a safety note for each substance used
• Advice on running the class at a different temperature or with a different salt, so the practice data is not the answer key
• Common slips to watch for

All questions are original. This is an independent resource, not endorsed by Pearson Edexcel.