Unit Overview

Experimental Techniques and Chemical Analysis

CIE IGCSE Chemistry· 5 min read 📊 15-20% of MCQ, theory, and practical assessment papers

1. Unit at a glance

You will begin with foundational measurement and titration skills, critical for reliable quantitative practical work, before moving to separation and purification methods for different types of mixtures. The unit concludes with qualitative analysis test protocols you will use to identify unknown chemical samples in both theory and practical assessments.

Work through the following subtopics in order to build practical proficiency step-by-step:

Apparatus, Measurement and Titration Technique

Learn to select appropriate lab apparatus, take precise measurements, and perform acid-base titrations accurately.

★★★⏱ 10 min

Separation, Purification and Chromatography

Master common separation techniques (filtration, distillation, crystallisation) and interpret paper chromatography results.

★★⏱ 9 min

Identification of Ions and Gases (Qualitative Analysis)

Memorise standard qualitative test procedures and key observations for identifying common ions and gases.

★★★★⏱ 12 min

2. Common Pitfalls

Wrong move:

Using a measuring cylinder for titration volume measurements

Why:

Measuring cylinders have high measurement error, leading to unreliable and imprecise titre values

Correct move:

Use a burette for adding titrant and a volumetric pipette for measuring fixed volumes of analyte

Wrong move:

Assuming all visible spots on chromatography paper are pure compounds

Why:

Mixtures of similarly structured coloured compounds may not separate fully under standard solvent conditions

Correct move:

Compare calculated $R_{f}$ values against known pure reference samples run on the same chromatography paper

Wrong move:

Using a glowing splint to test for carbon dioxide

Why:

A glowing splint only identifies oxygen; CO2 will extinguish it, but so will many other non-flammable gases

Correct move:

Use limewater, which turns milky in the presence of carbon dioxide, to confirm the identity of the gas

3. Quick Reference Cheatsheet

Rule/Formula	Use Case
Titration calculation: $\frac{M _{1} V _{1}}{n _{1}} = \frac{M _{2} V _{2}}{n _{2}}$	Calculate unknown concentration of acid/alkali from titre values
$R_{f} = \frac{Distance moved by substance}{Distance moved by solvent front}$	Identify unknown compounds from chromatography results
Ammonium test: Warm sample with NaOH, test gas with damp red litmus	Detect $N H_{4}^{+}$ ions (litmus turns blue if present)
Sulfate test: Acidify with dilute $H N O_{3}$ , then add $B a (N O_{3})_{2}$ solution	Detect $S O_{4}^{2 -}$ ions (white precipitate forms if present)
Hydrogen test: Hold lit splint near open test tube mouth	Detect $H_{2}$ gas (squeaky pop sound occurs if present)

What's Next

Start your learning with the first subtopic on apparatus, measurement, and titration to build foundational practical skills you will apply across all subsequent experimental work. Once you complete this full unit, you will progress to the chemical energetics unit, where you will apply your measurement skills to enthalpy change experiments.