Edexcel IGCSE Chemistry Investigation Variables

Edexcel IGCSE Chemistry Investigation Variables
Edexcel IGCSE Chemistry syllabusChemistry 4CH1Issue 3 (2024)

Practise Edexcel IGCSE Chemistry investigation variables by choosing what to keep constant, including concentration, volume, mass and temperature.

How this is tested

  • State controlled variables such as concentration, volume, mass, surface area or temperature.
  • Choose control variables that make reaction-rate or comparison results valid.

Question 8(d)(i)

[Maximum number: 2]

A student uses this apparatus to investigate the rate of reaction between marble chips and dilute hydrochloric acid.

Figure for Question 8(d)(i) — Edexcel IGCSE Chemistry

This is the equation for the reaction.

CaCO3( s)+2HCl(aq)→CaCl2(aq)+H2O(l)+CO2( g)\mathrm{CaCO}_{3}(\mathrm{~s})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{CaCl}_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})+\mathrm{CO}_{2}(\mathrm{~g})

The student repeats the experiment with hydrochloric acid at a higher temperature to investigate the effect on the rate of reaction.

Give two variables that should be controlled to make sure the results are valid.

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