Solutions & Solubility — Drills · Grade 11 Science

Chapter: Solutions & Dissolved Particles

What these drills covers

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

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

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

Problem 1

In a cup of seawater, which part is the solvent?
  1. the water
  2. the sand at the bottom
  3. the cup
  4. the dissolved salt
Answer and explanation

the water

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

Problem 2

An unsaturated solution is one that…
  1. has already formed a precipitate
  2. can still dissolve more solute
  3. holds all the solute it possibly can
  4. contains no solute at all
Answer and explanation

can still dissolve more solute

An unsaturated solution has not yet reached its limit, so it can dissolve more solute.

Problem 3

The solubility of a salt is 40 g per 100 g of water. How many grams will dissolve in 200 g of water at the same temperature?
Answer and explanation

80 g

200 g of water is 2 times 100 g, so 40 g × 2 = 80 g dissolves.

Problem 4

Why does oil fail to dissolve in water?
  1. oil is too heavy to mix
  2. water is nonpolar and oil is polar
  3. oil is nonpolar while water is polar, so 'like dissolves like' does not apply
  4. the water is already saturated with air
Answer and explanation

oil is nonpolar while water is polar, so 'like dissolves like' does not apply

Water is polar and oil is nonpolar; because 'like dissolves like,' polar water cannot pull nonpolar oil apart.

Problem 5

Grinding a solute into a fine powder makes it dissolve faster, yet it does not raise the maximum amount that can dissolve. Explain why.
Answer and explanation

Grinding increases 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 6

At 25°C a salt's solubility is 38 g per 100 g of water. If you stir 60 g of the salt into 100 g of water at 25°C, how many grams remain undissolved?
Answer and explanation

22 g

Only 38 g can dissolve in 100 g of water, so 60 g − 38 g = 22 g stays undissolved.

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