Edexcel IGCSE Chemistry Precise Observations

Practise Edexcel IGCSE Chemistry precise observations by recognising colour, effervescence and gas syringe evidence during reactions.

Exam points

State a solution colour accurately, such as blue for copper(II) sulfate solution.
Recognise that a reaction has stopped when fizzing ends or no more gas is collected.

[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 Precise observations and measurements question 1 — Edexcel IGCSE Chemistry

This is the student's method.
Step 1 use $50 \mathrm{~cm}^{3}$ 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

State how the student would know when the reaction stops.

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Precise observations and measurements question 1