A free printable solubility curves worksheet for Grade 11 chemistry.
Students read a six-substance solubility graph, identify saturated and unsaturated solutions, calculate how much solid crystallizes on cooling, scale solubility to other masses of water, explain gas solubility and “like dissolves like”, and find the percent by mass of a saturated solution. Includes 22 questions (22 marks) and a full answer key.
This free solubility curve worksheet gives students a large, easy-to-read solubility graph for six substances, including a gas, and walks them through every skill that goes with it. They read values off the curves, find where two curves cross, and decide whether solutions are saturated or unsaturated.
Students then calculate how much solid crystallizes when a solution cools, scale solubility to other masses of water, apply "like dissolves like", and find the percent by mass of a saturated solution. Every reading and calculation in the answer key comes straight from the plotted data, with acceptable ranges for graph readings.
Saturated vs unsaturated; crystallization on cooling
5
C
Scaling to other masses of water
3
D
Gas solubility and "like dissolves like"
4
E
Percent by mass of a saturated solution
2
F
Spot the mistake
2
It supports the Ontario Grade 11 chemistry curriculum expectations in the Solutions and Solubility unit.
The Solubility Graph
Each curve shows the maximum mass of a substance that dissolves in 100 g of water at each temperature. Most solids, like KNO₃, get much more soluble as water warms. NaCl barely changes. The ammonia curve slopes down because it is a gas. KNO₃ and NaNO₃ cross at about 69 °C, where both dissolve about 134 g. For more background, see solubility on Wikipedia.
Substance
0 °C
20 °C
40 °C
60 °C
80 °C
100 °C
KNO₃
13.3
31.6
63.9
110
169
246
NaNO₃
73
88
104
124
148
180
NH₄Cl
29.4
37.2
45.8
55.2
65.6
77.3
NaCl
35.7
36
36.6
37.3
38.4
39.8
KClO₃
3.3
7.3
13.9
23.8
35.5
50
NH₃ (gas)
88
56
34
20
11
6
Saturated, Unsaturated and Supersaturated
Plot a solution's mass of solute against its temperature. A point on the curve is saturated, below the curve is unsaturated, and above it is supersaturated, or saturated with leftover solid. For example, 40 g of NaCl in 100 g of water at 20 °C is above the curve: only 36 g dissolves and about 4 g stays at the bottom. Part B of the solubility curve worksheet practises this with three solutions.
Crystallization and Scaling
When a saturated solution cools, the extra solute crystallizes out. Dissolving 100 g of KNO₃ at 70 °C and cooling it to 30 °C leaves only 46 g dissolved, so about 54 g of crystals form.
Solubility curves are always "per 100 g of water", so scale for other amounts: in 50 g of water, KNO₃ at 40 °C dissolves 64 × 50/100 ≈ 32 g. The molarity worksheet covers concentration in mol/L.
What Affects Solubility
Temperature: most solids become more soluble when heated; gases become less soluble.
Polarity: "like dissolves like". Polar and ionic substances dissolve in water; nonpolar ones like oil don't. The ionic or covalent worksheet reviews bond types.
Pressure (gases only): higher pressure dissolves more gas, which is why soda fizzes when opened.
Stirring and crushing only change how fast something dissolves, not how much. This solubility curve worksheet tests that idea in Part F.
Solubility Curve Worksheet Practice Questions
These questions match the solubility curve worksheet PDF and use the graph above.
Part A – Reading the Graph
What is the solubility of KNO₃ at 50 °C?
At what temperature does 50 g of NH₄Cl dissolve in 100 g of water?
Which substance’s solubility changes the least as temperature rises?
Which substance is the least soluble at 20 °C?
Which curve slopes downward? What does this tell you about that substance?
At what temperature do KNO₃ and NaNO₃ have the same solubility?
Part B – Saturation and Crystallization
60 g of KNO₃ is dissolved in 100 g of water at 40 °C. Is the solution saturated or unsaturated? Explain.
40 g of NaCl is stirred into 100 g of water at 20 °C. Is the solution saturated? How much NaCl stays undissolved?
80 g of NH₄Cl is added to 100 g of water at 70 °C. How much will not dissolve?
100 g of KNO₃ is dissolved in 100 g of water at 70 °C and then cooled to 30 °C. What mass of crystals forms? (2 marks)
Part C – Other Masses of Water
What mass of KNO₃ dissolves in 50 g of water at 40 °C?
What mass of NaNO₃ dissolves in 250 g of water at 20 °C?
What is the minimum mass of water needed to dissolve 30 g of KClO₃ at 70 °C?
Part D – What Affects Solubility
Explain why gases become less soluble as water gets warmer.
Use your answer to explain why fish can struggle in warm water near a power plant outflow.
Does sodium chloride dissolve in water?
Does vegetable oil dissolve in water?
Does sugar dissolve in water?
Does iodine, i₂ dissolve in water?
Part E – Concentration
Calculate the percent by mass of a saturated NaCl solution at 20 °C. (2 marks)
Part F – Spot the Mistake
A student says: “Stirring increases the solubility of sugar in water.” Explain the error and correct it.
A student says: “Heating a solution always lets more solute dissolve.” Explain the error and correct it.
Solubility Curve Worksheet Answer Key
Open each part of the solubility curve worksheet answers to check your work. The printable key is at the end of the PDF.
Part A answers (Q1–6)
About 86 g per 100 g water (accept 82–88 g)
About 49 °C (accept 48–52 °C)
NaCl (its curve is almost flat)
KClO₃ (about 7 g)
NH₃. It is a gas, and gases become less soluble as temperature increases.
Where the curves cross: about 69 °C (accept 67–71 °C), at about 134 g
Part B answers (Q7–10)
Unsaturated: 60 g is below the curve (64 g can dissolve at 40 °C).
Saturated; only 36 g dissolves, so about 4 g stays undissolved.
60 g dissolves, so about 20 g stays undissolved.
At 30 °C only 46 g stays dissolved, so 100 − 46 = about 54 g of crystals form.
Part C answers (Q11–13)
64 × 50/100 = about 32 g
88 × 250/100 = 220 g
30 ÷ 29.5 × 100 = about 102 g of water
Part D answers (Q14–19)
Gas particles gain kinetic energy and escape from the liquid more easily.
Warm water holds less dissolved oxygen, so there is less oxygen for fish to breathe.
Dissolves
Does not dissolve
Dissolves
Does not dissolve
Part E answer (Q20)
36.0 g ÷ (100 + 36.0) g × 100% = 26.5%
Part F answers (Q21–22)
Stirring only makes sugar dissolve faster. Solubility (the maximum that can dissolve) depends on temperature.
That is true for most solids, but gases such as NH₃ and O₂ become less soluble when heated.
5 Common Solubility Curve Mistakes
Forgetting "per 100 g of water". Always scale when the mass of water is different.
Confusing rate and solubility. Stirring and heating speed up dissolving; only temperature changes solubility for solids.
Reading the wrong curve. Trace your finger along the curve before reading across.
Subtracting backwards. Crystals formed = mass dissolved at the start − solubility at the lower temperature.
Using mass of water in percent by mass. Divide by the mass of the whole solution (solute + water).
How to Use This Solubility Curve Worksheet in Class
Lesson 1: Parts A–C of the solubility curve worksheet, after a demo of KNO₃ crystallizing from a cooling solution.
Lesson 2: Parts D–F, linking gas solubility to thermal pollution and carbonated drinks.
Lab link: Students build their own KNO₃ curve by measuring crystallization temperatures.
Yes. The worksheet and its answer key are free to download and print as a PDF, with no account needed.
How do you read a solubility curve?
Find the temperature on the x-axis, go up to the substance's curve, then read across to the y-axis. The value is the maximum mass of solute that dissolves in 100 g of water at that temperature.
How can you tell if a solution is saturated from a solubility curve?
Plot the mass of solute against the temperature. A point on the curve is saturated, below the curve is unsaturated, and above the curve is supersaturated (or saturated with extra solid left over).
Why do some solubility curves slope downward?
Downward curves belong to gases such as ammonia. Gases escape more easily from warm water, so their solubility drops as temperature rises.
What grade is this solubility curve worksheet for?
It is written for Grade 11 chemistry (the Solutions and Solubility unit) and also works for Grade 10 science extension.
Ready to start? Download the free solubility curve worksheet PDF (use the Download button above), print it double-sided, and keep the answer key pages for marking.