Edexcel IGCSE Chemistry Practical Contexts

Edexcel IGCSE Chemistry Practical Contexts
Edexcel IGCSE Chemistry syllabusChemistry 4CH1Issue 3 (2024)

Practise Edexcel IGCSE Chemistry practical contexts by applying chemical ideas to excess reagents, gas expansion and measurement precision.

How this is tested

  • Explain bubbles at the start of heating as air or gas expanding in the apparatus.
  • Justify why exact mass or volume measurement is unnecessary when a reagent is in excess.

Question 7(a)(ii)

[Maximum number: 1]

A student uses this apparatus to investigate the rate of reaction between dilute sulfuric acid and an excess of small pieces of zinc.

Figure for Question 7(a)(ii) — Edexcel IGCSE Chemistry

This is the student's method.
Step 1 use 50 cm350 \mathrm{~cm}^{3} of dilute sulfuric acid
Step 2 add approximately 5 g of small zinc pieces to the sulfuric acid
Step 3 quickly connect the gas syringe
Step 4 record the reading on the gas syringe every 30 seconds until the reaction stops

Give a reason why the mass of zinc pieces does not need to be measured accurately.