H2 Chemistry Notes: CORE IDEA 2, Topic 3 - The Gaseous State

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10 Feb 2025, 00:00 Z

Q: What does H2 Chemistry Notes: CORE IDEA 2, Topic 3 - The Gaseous State cover? A: Review gas laws, kinetic molecular theory, real gas behaviour, and quantitative applications for Core Idea 2 (The Gaseous State) in the 2026 H2 Chemistry syllabus.

Gas behaviour threads through stoichiometry, energetics, and even kinetics questions. This chapter synthesises ideal gas assumptions, deviations, and exam-grade calculations so you handle Paper 2 and Paper 3 prompts efficiently. Additional revision materials live at https://eclatinstitute.sg/blog/h2-chemistry-notes.

1 Ideal Gas Law Refresher

The combined gas law condenses into the familiar ideal gas equation $PV = nRT$ . Here $P$ is measured in $\pu{Pa}$ , $V$

Law	Statement	Use
Boyle's	\(P \propto \frac{1}{V}\) at constant \(n\) and \(T\).	Predict compression effects.
Charles'	\(V \propto T\) at constant \(n\) and \(P\).	Thermal expansion.
Gay-Lussac's	\(P \propto T\) at constant \(n\) and \(V\).	Pressure-temperature calibrations.
Avogadro's	\(V \propto n\) at constant \(P\) and \(T\).	Relating gas volumes to moles.

Deviation	Cause	Correction
Volume smaller than predicted	Attractive forces dominate, pulling molecules closer.	Add \(\dfrac{a n^{2}}{V^{2}}\) to \(P\) in the van der Waals correction.
Volume larger than predicted	Finite size of molecules becomes significant.	Subtract \(nb\) from \(V\) in the van der Waals correction.

H2 Chemistry Notes: CORE IDEA 2, Topic 3 - The Gaseous State

1 Ideal Gas Law Refresher

1.1 Gas Law Quick Checks

2 Kinetic Molecular Theory (KMT)

3 Real Gas Deviations

4 Partial Pressure and Gas Mixtures

5 Worked Example

6 Experimental Contexts

7 Common Errors

8 Quick Practice Drill

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