AI SearchTopicalsYearlysNotesDashboardPricing
9701/13

Chemistry 9701/13 — May/June 2011

Cambridge AS Level · Multiple Choice (AS Level) · answer key with instant marking and worked solutions

40
questions
40
marks
60
minutes

Topics Introduction to Organic Chemistry · Hydroxy Compounds · Atoms, Molecules and Stoichiometry · Chemical Bonding · Nitrogen and Sulfur · Reaction Kinetics · +13 more

Tap an option under each question to check it — your score builds as you go.

Q11MAtomic StructureFree sample

Which equation represents the second ionisation energy of an element X?

Options

A   X(g)→X2+(g)+2e−\text{X(g)} \rightarrow \text{X}^{2+}\text{(g)} + 2\text{e}^-
B   X+(g)→X2+(g)+e−\text{X}^+\text{(g)} \rightarrow \text{X}^{2+}\text{(g)} + \text{e}^-
C   X(g)+2e−→X2−(g)\text{X(g)} + 2\text{e}^- \rightarrow \text{X}^{2-}\text{(g)}
D   X−(g)+e−→X2−(g)\text{X}^-\text{(g)} + \text{e}^- \rightarrow \text{X}^{2-}\text{(g)}

DifficultyEasy
Worked solution

Working

Second ionisation energy is the energy required to remove one electron from each gaseous 1+ ion to form a gaseous 2+ ion:

X+(g)→X2+(g)+e−\text{X}^+\text{(g)} \rightarrow \text{X}^{2+}\text{(g)} + \text{e}^-

Answer

B

Final answer

B

Detailed explanation

Background Concept

Ionisation energy is the energy required to remove an electron from a gaseous atom or ion. The first ionisation energy removes one electron from a neutral gaseous atom. The second ionisation energy removes one electron from a gaseous ion that already has a 1+ charge.

Understanding the Question

The question asks which equation correctly represents the second ionisation energy of an element X. The key features are:

  • The species must be in the gaseous state.
  • The starting species must be X⁺(g).
  • The product must be X²⁺(g) and one electron must be removed.

Approach

Check each option against the definition:

  • Does the reactant have a 1+ charge?
  • Is the product a 2+ ion?
  • Is one electron removed?
  • Are all species gaseous?

Step-by-Step Reasoning

  1. Option A: X(g) → X²⁺(g) + 2e⁻. This removes two electrons from a neutral atom, so it represents the sum of the first and second ionisation energies, not the second ionisation energy alone.
  2. Option B: X⁺(g) → X²⁺(g) + e⁻. This removes one electron from a gaseous 1+ ion to form a gaseous 2+ ion. This matches the definition exactly.
  3. Option C: X(g) + 2e⁻ → X²⁻(g). This involves gaining electrons, so it is not ionisation at all.
  4. Option D: X⁻(g) + e⁻ → X²⁻(g). This also involves gaining an electron by a negative ion, so it is not ionisation.

Therefore, the correct answer is B.

Key Takeaways

  • Ionisation always involves removing an electron from a gaseous species.
  • The second ionisation energy starts from a gaseous 1+ ion, not from a neutral atom.
  • State symbols are important: ionisation energies are defined for gaseous species.

Common Mistakes

  • Choosing A because it produces X²⁺, forgetting that it removes two electrons from the neutral atom.
  • Confusing ionisation with electron gain, which would lead to C or D.

Things to Be Careful About

  • Read the charge on the starting ion carefully.
  • Remember that the second ionisation energy is always larger than the first because the electron is being removed from a positively charged ion.
  • Always include the gaseous state in the definition.
Techniques used
define ionisation energyidentify the species and state symbols in each option

The rest of this paper

39 more questions
  • Q2Atomic Structure1M
  • Q3States of Matter1M
  • Q4Nitrogen and Sulfur · Electrochemistry1M
  • Q5Equilibria1M
  • Q6Reaction Kinetics · Atoms, Molecules and Stoichiometry1M
  • Q7Reaction Kinetics1M
  • Q8Chemical Energetics1M
  • Q9Chemical Energetics1M
  • Q10Chemical Bonding1M
  • Q11Reaction Kinetics1M
  • Q12Atoms, Molecules and Stoichiometry1M
  • Q13States of Matter1M
  • Q14Group 21M
  • Q15Nitrogen and Sulfur1M
  • Q16Group 171M
  • Q17Group 171M
  • Q18Nitrogen and Sulfur · Atoms, Molecules and Stoichiometry1M
  • Q19Nitrogen Compounds · Halogen Compounds1M
  • Q20Introduction to Organic Chemistry1M
  • Q21Introduction to Organic Chemistry · Carboxylic Acids and Derivatives1M
  • Q22Hydrocarbons · Hydroxy Compounds1M
  • Q23Hydroxy Compounds · Carbonyl Compounds1M
  • Q24Carbonyl Compounds1M
  • Q25Introduction to Organic Chemistry1M
  • Q26Hydroxy Compounds · Introduction to Organic Chemistry1M
  • Q27Chemical Bonding · Introduction to Organic Chemistry1M
  • Q28Carboxylic Acids and Derivatives1M
  • Q29Hydroxy Compounds1M
  • Q30Carbonyl Compounds1M
  • Q31Chemical Bonding1M
  • Q32Atoms, Molecules and Stoichiometry1M
  • Q33Equilibria1M
  • Q34Chemical Bonding1M
  • Q35Group 171M
  • Q36Chemical Periodicity1M
  • Q37Hydrocarbons · Introduction to Organic Chemistry1M
  • Q38Chemical Periodicity1M
  • Q39Hydroxy Compounds1M
  • Q40Halogen Compounds1M
Loading the full paper…