Solution Stoichiometry — Practice · Grade 11 Science

Chapter: Stoichiometry & Yield

What this practice covers

By the end of Solution Stoichiometry you should be able to:

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

Vocabulary used: equivalence, aliquot.

Problem 1

Find moles in 0.250 L of 0.400 M solution.
Hints

Write the relationship first; substitute with consistent units.

Answer and explanation

0.1 mol

.400×.250=.100.

Problem 2

Why can equal solution volumes require unequal reacting amounts?
Answer and explanation

Their molarities and reaction coefficients can differ.

Response criteria

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

Problem 3

Find mL of .20 M NaOH needed for .0040 mol HCl in a 1:1 reaction.
Hints

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

Answer and explanation

20 mL

.0040/.20=.020L=20 mL.

Problem 4

Compare dilution and neutralization equations.
Answer and explanation

Dilution preserves solute moles; neutralization transforms species according to a balanced equation.

Response criteria

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

Problem 5

Find solute moles in 0.025 L of 0.40 M solution. Show the reasoning, not just the conclusion.
Hints

Use liters in n=MV.

Answer and explanation

n=0.40×0.025=0.010 mol.

Problem 6

Equal volumes of 0.10 M Ag⁺ and 0.20 M Cl⁻ react 1:1. Which ion limits?
Hints

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

Answer and explanation

Ag⁺, because equal volumes give half as many moles of Ag⁺ as Cl⁻.

Problem 7

Reaction bookkeeping comes before calculating the final concentrationReaction bookkeeping comes before calculating the final concentrationMixing accountBefore reactionAfter reaction/mixingSolute amountComputed in each portionSubtract what reactsSolution volumeTwo measured portionsUse measured final VConcentrationEach initial cRemaining n / final VAssuming additive volumes is a stated approximation.
Original bookkeeping organizer; it supplies the calculation order rather than numerical solution-volume measurements.
Interpret the supplied visual. Why is dividing initial acid moles by total mixed volume not enough after adding a reacting base?
Answer and explanation

Some acid is consumed. Reaction bookkeeping must determine the remaining amount before the final-volume division.

When solutions mix, a reacting ion can be consumed while spectator ions remain. Calculate each initial amount, apply stoichiometry, then divide remaining amount by the final solution volume. Adding volumes is a common dilute-solution school approximation, not an exact law for every mixture. The concentration of a spectator can decrease by dilution without the spectator being consumed. A final mixture can contain several species with different concentrations, so keep a separate inventory for each named species.

Some acid is consumed. Reaction bookkeeping must determine the remaining amount before the final-volume division.

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

Mix 10.0 mL of 0.200 M AgNO₃ with 15.0 mL of 0.100 M NaCl. Assume complete AgCl precipitation and additive volumes. Find limiting ion, AgCl moles and remaining Ag⁺ concentration.
Answer and explanation

Ag⁺ starts at 0.00200 mol and Cl⁻ at 0.00150 mol, so chloride limits. AgCl forms 0.00150 mol; remaining Ag⁺ is 0.00050 mol in 0.0250 L, or 0.0200 M under the stated model.

Ag⁺ starts at 0.00200 mol and Cl⁻ at 0.00150 mol, so chloride limits. AgCl forms 0.00150 mol; remaining Ag⁺ is 0.00050 mol in 0.0250 L, or 0.0200 M under the stated model.

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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