“States of Matter: Gases, Liquids and Solids”

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

States of Matter: Gases, Liquids and Solids — Key Facts Ideal gas equation: $PV = nRT$; $R = 8.314$ J/mol·K = 0.0821 L·atm/mol·K Standard molar volume: 22.4 L at STP (0°C, 1 atm) for ideal gas Graham’s law of diffusion: $\frac{r_1}{r_2} = \sqrt{\frac{M_2}{M_1}}$; lighter gases diffuse faster Kinetic theory assumptions: negligible molecular volume, no intermolecular forces, random motion, elastic collisions ⚡ Exam tip: Real gases deviate from ideal behaviour at high pressure and low temperature

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

States of Matter: Gases, Liquids and Solids — JAMB Chemistry Study Guide

Gas laws:

• Boyle’s: $P_1V_1 = P_2V_2$ (constant $n, T$)
• Charles: $V_1/T_1 = V_2/T_2$ (constant $n, P$)
• Gay-Lussac: $P_1/T_1 = P_2/T_2$ (constant $n, V$)
• Avogadro: $V/n = constant$ → equal volumes of gases at same $T, P$ contain equal molecules

Dalton’s law of partial pressures: $P_{total} = P_1 + P_2 + P_3 + …$; $P_i = y_i \times P_{total}$ (where $y_i$ = mole fraction) Partial pressure: $P_i = n_iRT/V$

Intermolecular forces (IMF):

• London dispersion forces: all molecules; strength increases with molecular weight and surface area; explains why $Br_2$ (liquid) > $Cl_2$ (gas) at RT
• Dipole-dipole: between polar molecules; e.g., HCl, $CH_3Cl$
• Hydrogen bonding: special case — H bonded to F, O, or N; explains high BP of $H_2O$, $NH_3$, $HF$
• Ion-dipole: between ions and polar molecules; e.g., $NaCl$ dissolving in water

Phase changes: Solid → Liquid = melting (requires latent heat of fusion); Liquid → Gas = vaporisation (requires latent heat of vaporisation); Solid → Gas = sublimation.

Critical temperature and pressure: Critical temperature = temperature above which gas cannot be liquefied by pressure alone; critical pressure = pressure needed to liquefy at critical temperature. $LPG$ (liquefied petroleum gas): mainly propane and butane; liquefied at moderate pressure at room temperature because $T_{crit}$ is above room temperature.

Common student mistakes: Confusing $R$ values (use correct units); forgetting that Graham’s law compares rates of diffusion, not speeds; not understanding why helium balloons float (He less dense than air).

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

States of Matter: Gases, Liquids and Solids — Comprehensive Chemistry Notes

Van der Waals equation (real gas correction): Ideal: $(P + \frac{an^2}{V^2})(V - nb) = nRT$ Where $a$ corrects for intermolecular attractions (lower effective pressure); $b$ corrects for finite molecular volume.

Kinetic molecular theory: For ideal gas, average kinetic energy: $\frac{1}{2}mv_{rms}^2 = \frac{3}{2}kT$ Root mean square speed: $v_{rms} = \sqrt{\frac{3RT}{M}}$ Distribution of speeds: Maxwell-Boltzmann; at higher $T$, distribution shifts to higher speeds and becomes broader.

Liquids — surface tension and viscosity: Surface tension $\gamma$: energy required to increase surface area by 1 m²; causes droplets to be spherical; increases with stronger IMF. Viscosity: resistance to flow; liquids with strong IMF (hydrogen bonding) are more viscous; decreases with temperature.

Solids — crystal types:

Type	Example	Forces	Properties
Ionic	NaCl	Electrostatic	High MP, brittle, conduct when molten
Covalent network	SiO₂ (quartz)	Covalent bonds	Very high MP, hard
Molecular	I₂, CO₂	IMF (LDF)	Low MP, soft
Metallic	Cu, Fe	Metallic bond	Malleable, conduct electricity
Hydrogen-bonded	Ice	H-bonding	Open structure, ice less dense than water

X-ray diffraction: Used to determine crystal structure; Bragg’s equation: $n\lambda = 2d\sin\theta$

JAMB exam patterns:

• 2023 JAMB: 2 g of gas occupies 1.2 L at 300 K and 1 atm; find molar mass
• 2022 JAMB: Which gas diffuses faster — NH₃ or HCl? Calculate the ratio
• 2021 JAMB: State and explain the effect of increasing temperature on viscosity of water
• 2020 JAMB: Why does ice float on water? Explain using structure and bonding

Properties comparison:

Property	Gas	Liquid	Solid
Shape	Takes container	Takes container	Fixed
Volume	Fills container	Fixed	Fixed
Compressibility	High	Very low	Negligible
Density	Low	High	Highest
Arrangement	Random, far apart	Random, close	Ordered, close

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📊 JAMB Exam Essentials

Detail	Value
Questions	180 MCQs (UTME)
Subjects	4 subjects (language + 3 for course)
Time	2 hours
Marking	+1 per correct answer
Score	400 max (used for university admission)
Registration	January – February each year

🎯 High-Yield Topics for JAMB

• Use of English (Grammar + Comprehension) — 60 marks
• Biology for Science students — 40 marks
• Chemistry (Organic + Physical) — 40 marks
• Physics (Mechanics + Optics) — 35 marks
• Mathematics (Algebra + Geometry) — 40 marks

📝 Previous Year Question Patterns

• Q: “The process of photosynthesis requires…” [2024 Biology]
• Q: “The electronic configuration of Fe is…” [2024 Chemistry]
• Q: “Find the value of x if 2x + 5 = 15…” [2024 Mathematics]

💡 Pro Tips

• Use of English carries the most weight — master grammar rules and comprehension strategies
• JAMB syllabus is your Bible — questions come directly from it. Download and use it.
• Past questions are highly predictive — repeat patterns appear every year
• For Science students, Biology and Chemistry are high-scoring if you study NCERT-level content

🔗 Official Resources

• JAMB Official
• JAMB Syllabus

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