AP®ChemistryCollege BoardExam QuestionsUnit 4: Chemical ReactionsChemical Changes

Chemical Changes (College Board AP® Chemistry)

Exam Questions

16 mins9 questions

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Chemical Changes

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Chemical Changes

11 mark

Which of the following is an example of a physical change?

  • Burning of wood

  • Fermentation of grapes

  • Melting of ice

  • Rusting of iron

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21 mark

What of the following is a key characteristic of a chemical change?

  • New substances with different properties are formed.

  • The appearance of the substance changes.

  • The mass of the substance changes.

  • The state of matter changes.

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31 mark

Which of the following comparisons of chemical and physical processes is the most accurate?

  • Chemical and physical processes are characterized by changes in intramolecular forces.

  • Chemical and physical processes are characterized by changes only in intermolecular forces.

  • Chemical processes are characterized by changes in intramolecular forces, while physical processes are characterized by changes only in intermolecular forces.

  • Physical processes are characterized by changes in intramolecular forces, while chemical processes are characterized by changes only in intermolecular forces.

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41 mark

Aqueous Pb(NO3)2 reacts with aqueous KI to produce a solid precipitate of PbI2 and aqueous KNO3.

Which of the following is the balanced net ionic equation for the reaction described above?

  • K+ (aq) + NO3- (aq) → KNO3(aq)

  • Pb(NO3)2 (aq) + 2I- (aq) → PbI2 (s) + 2NO3- (aq)

  • Pb2+ (aq) + I- (aq) → PbI2 (s)

  • Pb2+ (aq) + 2I- (aq) → PbI2 (s)

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51 mark
Molecular representation of carbon monoxide reacting with oxygen

The diagram above shows a reaction between carbon monoxide and oxygen.

Which of the following equations best describes the reaction?

  • C (g) + 2O2 (g) → CO2 (g)

  • 2CO (g) + O2 (g) → 2CO2 (g)

  • CO (g) + O2 (g) → CO2 (g)

  • 6CO (g) + 5O2 (g) → 6CO2 (g) + 2O2 (g)

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61 mark

What is the balanced molecular equation when Na2CO3 (aq) is mixed with HCl (aq)?

  • Na2CO3 (aq) + 2HCl (aq) → 2NaCl (aq) + H2O (l) + CO2 (g)

  • Na2CO3 (aq) + HCl (aq) → Na2Cl (aq) + H2O (l) + CO2 (g)

  • 2Na2CO3 (aq) + 2HCl (aq) → 2NaCl (aq) + H2O (l) + CO2 (g)

  • Na2CO3 (aq) + HCl (aq) → NaCl (aq) + H2O (l) + CO2 (g)

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71 mark

When the equation below is balanced, what is the mole ratio of CO2 to H2O?

C3H5OH + O2 → CO2 + H2O

  • 1:1

  • 1:2

  • 2:1

  • 3:2

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81 mark

Which of the following best describes the change that takes place immediately after liquid ethanol is introduced into a previously evacuated vessel?

  • A chemical change takes place because covalent bonds are broken.

  • A chemical change takes place because intermolecular attractions are overcome.

  • A physical change takes place because covalent bonds are broken.

  • A physical change takes place because intermolecular attractions are overcome.

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