Solutions & Solubility — Practice · Grade 11 Science

Chapter: Solutions & Dissolved Particles

What this practice covers

By the end of Solutions & Solubility you should be able to:

9 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: solution, solute, solvent, solubility, saturated solution.

Problem 1

In a solution of sugar dissolved in water, which part is the solvent?
  1. the sugar
  2. the water
  3. the sweetness
  4. the glass
Answer and explanation

the water

The solvent does the dissolving and is present in the larger amount — here, the water.

Problem 2

A solution that contains the maximum amount of dissolved solute at a given temperature is described as…
  1. nonpolar
  2. unsaturated
  3. saturated
  4. dilute
Answer and explanation

saturated

A saturated solution holds all the solute it can at that temperature.

Problem 3

The solubility of potassium nitrate at 40°C is 64 g per 100 g of water. How many grams will dissolve in 300 g of water at 40°C?
Answer and explanation

192 g

300 g of water is 3 times 100 g, so 64 g × 3 = 192 g dissolves.

Problem 4

Stirring a solute and grinding it into a fine powder both make it dissolve faster, yet neither changes the maximum amount that can dissolve. Explain why.
Answer and explanation

Stirring and grinding increase the surface area where solvent meets solute, so dissolving happens at a faster rate. But the maximum that can dissolve — the solubility — depends on the temperature and the identities of the substances, not on how quickly you get there.

Problem 5

At 20°C the solubility of a certain salt is 34 g per 100 g of water. If you stir 50 g of the salt into 100 g of water at 20°C, how many grams remain undissolved at the bottom?
Answer and explanation

16 g

Only 34 g can dissolve in 100 g of water, so 50 g − 34 g = 16 g stays undissolved.

Problem 6

At solubility 20 g/100 g water, how much can 250 g water dissolve under the model? Show the reasoning, not just the conclusion.
Hints

Solubility is temperature-specific.

Answer and explanation

20×250/100=50 g.

Problem 7

Why can warming increase some solid solubilities but reduce dissolved gas amounts?
Hints

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

Answer and explanation

Different dissolution thermodynamics apply; there is no universal temperature direction for all substances.

Problem 8

Changing the rate need not change the equilibrium capacityChanging the rate need not change the equilibrium capacityDissolved solute mass (g)051015012345Time (relative)Unstirred modelStirred model
Original illustrative approach-to-equilibrium records; the curves are not experimental fits and apply to the stated fixed-condition model.
Interpret the supplied visual. What is the main difference between the two selected curves, and what stays the same?
Answer and explanation

The stirred model approaches the common 15 g plateau faster. The selected final equilibrium capacity is unchanged.

Dissolution rate is how quickly solute enters solution, while equilibrium solubility specifies a final capacity under stated conditions. Stirring and smaller particles can speed approach to saturation by improving transport or exposed area without changing the final equilibrium amount in the selected model. Temperature can affect both rate and equilibrium, with the direction depending on the system. A faster curve reaching the same plateau supports a rate difference, not a claim that stirring created extra solvent capacity.

The stirred model approaches the common 15 g plateau faster. The selected final equilibrium capacity is unchanged.

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 9

At a supplied temperature, solubility is 20.0 g solute per 100 g water. Add 30.0 g to 100 g water and allow equilibrium with excess solid. Find dissolved and undissolved masses and explain what stirring changes.
Answer and explanation

Under the stated model, 20.0 g dissolves and 10.0 g remains solid. Stirring can speed equilibration but does not change this selected equilibrium capacity at fixed conditions.

Under the stated model, 20.0 g dissolves and 10.0 g remains solid. Stirring can speed equilibration but does not change this selected equilibrium capacity at fixed conditions.

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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