AP problems

412 problems for AP practice, each with a worked solution. Try each one on paper first, then check your answer.

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All TopicsStates of MatterMixtures and SolutionsAtoms and MoleculesStructure of the AtomChemical ReactionsAcids, Bases and SaltsMetals and Non-metalsCarbon and Its CompoundsThe Periodic TableChemical BondingChemical Thermodynamics

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Type:AnyConceptualNumerical

1.

Predict the sign of Δ S for each change, and give the reason. New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityBoard Exam, AP, A-Level, IBStemPy Lab

Easy

2.

Sulphur trioxide is made by 2SO₂(g) + O₂(g) → 2SO₃(g). New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityBoard Exam, AP, A-Level, IBStemPy Lab

Medium

3.

For N₂(g) + 3H₂(g) → 2NH₃(g), Δ H° = -92.4 kJ/mol and Δ S° = -198.7 J/(K mol). New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityBoard Exam, AP, A-Level, IBStemPy Lab

Medium

4.

Magnesium carbonate decomposes: MgCO₃(s) → MgO(s) + CO₂(g), with Δ H° = +117.6 kJ/mol and Δ S° =… New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityBoard Exam, AP, A-Level, IBStemPy Lab

Medium

5.

Four reactions have these signs. (a) Δ H < 0, Δ S > 0. New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityBoard Exam, AP, A-Level, IBStemPy Lab

Easy

6.

At 298 K a reaction has Δ G° = -17.1 kJ/mol. New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityBoard Exam, AP, A-Level, IBStemPy Lab

Medium

7.

A reaction has K = 2.5 × 10⁻³ at 500 K. Find Δ G° at this temperature. New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityBoard Exam, AP, A-Level, IBStemPy Lab

Medium

8.

For N₂O₄(g) ⇌ 2NO₂(g), Δ H° = +57.2 kJ/mol and Δ S° = +175.8 J/(K mol). New

High School (11–12) · Entropy, Gibbs Energy and SpontaneityJEE Main, NEET, BITSAT, WBJEE, Board Exam, AP, A-Level, IBStemPy Lab

Hard

9.

50.0 mL of 1.00 M hydrochloric acid is mixed with 50.0 mL of 1.00 M sodium hydroxide in a… New

High School (11–12) · Enthalpy and Hess's LawBoard Exam, AP, A-Level, IBStemPy Lab

Easy

10.

Quicklime is made by heating limestone: CaCO₃(s) → CaO(s) + CO₂(g). New

High School (11–12) · Enthalpy and Hess's LawNEET, Board Exam, AP, A-Level, IBStemPy Lab

Medium

11.

On a cold dry morning, frost on a car turns straight to water vapour. New

High School (11–12) · Enthalpy and Hess's LawBoard Exam, APStemPy Lab

Easy

12.

How much heat turns 36.0 g of ice at 273 K into steam at 373 K? New

High School (11–12) · Enthalpy and Hess's LawNEET, Board Exam, AP, A-Level, IBStemPy Lab

Medium

13.

Methane cannot be made cleanly from carbon and hydrogen, so its Δf H° is found with Hess's law. New

High School (11–12) · Enthalpy and Hess's LawJEE Main, NEET, BITSAT, WBJEE, Board Exam, AP, A-Level, IB, GaokaoStemPy Lab

Medium

14.

Estimate Δr H for C₂H₄(g) + H₂(g) → C₂H₆(g) from the mean bond enthalpies: C=C 611, H-H 435, C-C… New

High School (11–12) · Enthalpy and Hess's LawNEET, Board Exam, AP, A-Level, IBStemPy Lab

Medium

15.

Breaking one mole of CH₄(g) into atoms takes 1665 kJ. New

High School (11–12) · Enthalpy and Hess's LawJEE Main, NEET, BITSAT, WBJEE, Board Exam, AP, A-Level, IB, GaokaoStemPy Lab

Hard

16.

Water boils at 373 K and hydrogen sulphide at 213 K, although an H₂S molecule is almost twice as… New

High School (11–12) · Molecular Orbitals and Hydrogen BondsBoard Exam, AP, A-Level, IBStemPy Lab

Easy

17.

Hydrogen sulphide, hydrogen selenide and hydrogen telluride boil at 213 K, 232 K and 271 K; their… New

High School (11–12) · Molecular Orbitals and Hydrogen BondsBoard Exam, AP, A-Level, IBStemPy Lab

Hard

18.

Silicon (4 outer electrons), phosphorus (5) and sulphur (6) each form a chloride: SiCl₄, PCl₃ and… New

High School (11–12) · Shapes of Molecules and HybridisationBoard Exam, AP, A-Level, IBStemPy Lab

Easy

19.

Xenon is a noble gas with 8 outer electrons, yet it forms XeF₂, XeF₄ and XeF₆. New

High School (11–12) · Shapes of Molecules and HybridisationNEET, Board Exam, AP, A-Level, IBStemPy Lab

Medium

20.

Predict the shapes of the ammonium ion NH₄⁺, the hydronium ion H₃O⁺ and the amide ion NH₂⁻. New

High School (11–12) · Shapes of Molecules and HybridisationBoard Exam, AP, A-Level, IBStemPy Lab

Medium

21.

Chlorine has 7 outer electrons. Find the electron pairs and lone pairs on chlorine in ClF₃. New

High School (11–12) · Shapes of Molecules and HybridisationBoard Exam, AP, A-Level, IBStemPy Lab

Hard

22.

Count the sigma and pi bonds in propene, CH₂=CH-CH₃, and in propyne, HC≡C-CH₃. New

High School (11–12) · Shapes of Molecules and HybridisationBoard Exam, AP, IBStemPy Lab

Medium

23.

Hydrogen chloride, chlorine and nitrogen are all covalent. New

High School (11–12) · Shapes of Molecules and HybridisationBoard Exam, AP, IBStemPy Lab

Medium

24.

Ethene, CH₂=CH₂, is flat. What is the hybridisation of each carbon atom? New

High School (11–12) · Shapes of Molecules and HybridisationBoard Exam, AP, IBStemPy Lab

Medium

25.

Count the valence electrons in the sulfate ion, SO₄²⁻. New

High School (11–12) · Lewis Structures and Ionic BondsBoard Exam, AP, IBStemPy Lab

Medium