Aqueous Reactions & Net Ionic Equations — Practice · Grade 11 Science

Chapter: Reactions, Moles & Composition

What this practice covers

By the end of Aqueous Reactions & Net Ionic Equations you should be able to:

8 questions, written answer and numeric, each with a worked explanation.

Vocabulary used: spectator ion, precipitate, electrolyte.

Problem 1

Identify spectators in silver nitrate plus sodium chloride.
Answer and explanation

Na⁺ and NO₃⁻ remain dissolved unchanged.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the calculation or mechanism that supports it.
  • Include units, conditions, or limits where relevant.

Problem 2

Why leave a solid intact in a net ionic equation?
Answer and explanation

It is not represented as independently mobile aqueous ions.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the calculation or mechanism that supports it.
  • Include units, conditions, or limits where relevant.

Problem 3

In Ag⁺+Cl⁻→AgCl(s), how many mol Ag⁺ react with 0.30 mol Cl⁻ if silver ions are sufficient?
Hints

List the given quantities, select a relationship, and check units before substituting.

Answer and explanation

0.3 mol

The ratio is 1:1.

Problem 4

Why is swapping ions not sufficient evidence of reaction?
Answer and explanation

If all species remain unchanged dissolved ions, no net chemical transformation is represented.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the calculation or mechanism that supports it.
  • Include units, conditions, or limits where relevant.

Problem 5

Given BaSO₄ insoluble, write the net ionic precipitation equation from Ba²⁺ and SO₄²⁻. Show the reasoning, not just the conclusion.
Hints

Atoms and total charge must balance.

Answer and explanation

Ba²⁺(aq)+SO₄²⁻(aq)→BaSO₄(s); total charge is zero on each side.

Problem 6

Why is a solid precipitate not split into free aqueous ions in the net equation?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Its state is a solid lattice; representing free aqueous ions would describe a different state.

Problem 7

Net ionic equations retain both composition and charge conservationNet ionic equations retain both composition and charge conservationNet processAtom checkCharge checkAg⁺ + Cl⁻ → AgCl(s)Ag 1; Cl 1 eachside0 → 0H₃O⁺ + OH⁻ → 2H₂OH 4; O 2 each side0 → 0H⁺(aq) is often shorthand for hydrated proton species.Keep the chosen water/proton notation consistent.
Original selected conservation table; hydronium notation is a simplified aqueous proton account, not a complete hydration-cluster model.
Interpret the supplied visual. Why does H₃O⁺+OH⁻ produce two water molecules rather than one in this explicit notation?
Answer and explanation

There are four hydrogen and two oxygen atoms on the reactant side; two H₂O preserve them along with total charge.

After cancellation, check atoms and total charge again. A precipitation equation can be neutral overall while containing charged reactants. For acid–base accounts, H⁺(aq) is a common shorthand; an explicit hydronium model uses H₃O⁺ and includes the corresponding water molecules. Do not mix notations in a way that loses hydrogen or oxygen atoms. The net equation identifies the dominant modeled transformation, not every short-lived microscopic intermediate or all equilibria in the solution.

There are four hydrogen and two oxygen atoms on the reactant side; two H₂O preserve them along with total charge.

Response criteria

  • Interpret labels, structures, axes, units and directions correctly.
  • Explain the chemistry relationship or mechanism.
  • Respect stated assumptions and distinguish observation from inference.

Problem 8

Write the net ionic equation when suitable aqueous BaCl₂ and Na₂SO₄ produce BaSO₄(s). Name spectators and verify charge. This is a supplied-species exercise, not a home experiment.
Answer and explanation

Ba²⁺(aq)+SO₄²⁻(aq)→BaSO₄(s). Na⁺ and Cl⁻ are spectators in the selected account. One Ba and one sulfate group are conserved and total charge is zero on each side.

Ba²⁺(aq)+SO₄²⁻(aq)→BaSO₄(s). Na⁺ and Cl⁻ are spectators in the selected account. One Ba and one sulfate group are conserved and total charge is zero on each side.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the chemical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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