SOLUTION: Solubility curve worksheet - Studypool - Free Printable

To solve these problems, we need to refer to solubility curves for various salts in water at different temperatures. Since the solubility curve is not provided in your image, I will use standard solubility data from common reference tables (typically found in chemistry textbooks or online resources) to answer each question.

Let’s go through each problem step by step.

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11. How many grams of sodium chloride, NaCl, are required to saturate 100 grams of water at 100°C?

- Solubility of NaCl at 100°C ≈ 39.2 g/100g water
- Answer: 39.2 g

> 🔹 Note: NaCl solubility increases only slightly with temperature.

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12. How many grams of NaNO₃ are required to saturate 100 grams of water at 90°C?

- Solubility of NaNO₃ at 90°C ≈ 148 g/100g water
- Answer: 148 g

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13. How many grams of KI will saturate water at 20°C?

- Solubility of KI at 20°C ≈ 144 g/100g water
- Answer: 144 g

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14. At what temperature would 25g of potassium chlorate (KClO₃) dissolve?

- Solubility of KClO₃:
- At 20°C → ~7.3 g/100g
- At 30°C → ~10 g
- At 40°C → ~13 g
- At 50°C → ~18 g
- At 60°C → ~25 g

So, 25 g of KClO₃ dissolves in 100 g water at about 60°C.

- Answer: 60°C

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15. At what temperature would 55g of NH₄Cl dissolve?

- Solubility of NH₄Cl:
- At 20°C → ~37 g
- At 30°C → ~41 g
- At 40°C → ~47 g
- At 50°C → ~50 g
- At 60°C → ~55 g

So, 55 g dissolves at ~60°C.

- Answer: 60°C

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16. 89 g NaNO₃ is prepared at 30°C.

#### a) Will all of the salt dissolve?

- Solubility of NaNO₃ at 30°C ≈ 95 g/100g water
- 89 g < 95 g → Yes, it will dissolve completely.

- Answer: Yes

#### b) What mass of NaNO₃ will dissolve at this temperature?

- Maximum that can dissolve = 95 g (but only 89 g added)

- So, 89 g will dissolve.

- Answer: 89 g

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17. If 25 grams of NH₄Cl is dissolved at 50°C, how many additional grams of NH₄Cl would be needed to make the solution saturated at 80°C?

- Solubility of NH₄Cl:
- At 50°C → ~50 g/100g water
- At 80°C → ~65 g/100g water

Already have 25 g dissolved in 100 g water at 50°C. Now heating to 80°C.

At 80°C, max solubility = 65 g → so additional amount needed:

65 g – 25 g = 40 g

- Answer: 40 g

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18. At 50°C, how many grams of KNO₃ will dissolve?

- Solubility of KNO₃ at 50°C ≈ 85 g/100g water
- Answer: 85 g

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19. At 70°C, how many grams of cerium(III) sulfate (Ce₂(SO₄)₃) dissolve?

- Ce₂(SO₄)₃ has low solubility, and its solubility decreases with temperature.
- At 70°C, solubility ≈ 10–12 g/100g water (approximate)
- More precisely: Around 11 g/100g water at 70°C (based on typical data)

- Answer: ~11 g

> 🔹 Note: This compound is not very soluble; values vary slightly depending on source.

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20. Determine if each of the following is unsaturated, saturated, or supersaturated.

We compare the given amount with the solubility at that temperature.

#### a. 55g of NH₄Cl at 20°C

- Solubility of NH₄Cl at 20°C ≈ 37 g/100g water
- 55 g > 37 g → Supersaturated? But supersaturation is unstable.
- However, since 55 g exceeds solubility, it cannot stay dissolved → supersaturated only if no crystals form; otherwise, it's not possible under normal conditions.

But typically, such solutions are considered supersaturated *if* they remain clear, but in reality, excess would crystallize.

But for classification purposes:
- 55 g > 37 g → Supersaturated (only if it remains dissolved without precipitation)

But usually, any amount above solubility is considered supersaturated (though unstable).

- Answer: Supersaturated

#### b. 10g of Ce₂(SO₄)₃ at 10°C

- Solubility of Ce₂(SO₄)₃ at 10°C ≈ ~15 g/100g water (slightly higher than at 70°C due to inverse solubility)
- 10 g < 15 g → Unsaturated

- Answer: Unsaturated

#### c. 125g of KNO₃ at 60°C

- Solubility of KNO₃ at 60°C ≈ 110 g/100g water
- 125 g > 110 g → Supersaturated (if no crystals form), but generally, excess won’t dissolve → Supersaturated

- Answer: Supersaturated

#### f. 80g of NaNO₃ at 10°C

- Solubility of NaNO₃ at 10°C ≈ 80 g/100g water (exactly!)
- So, Saturated

- Answer: Saturated

#### g. 145g of NaNO₃ at 80°C

- Solubility of NaNO₃ at 80°C ≈ 150 g/100g water
- 145 g < 150 g → Unsaturated

- Answer: Unsaturated

#### h. 35g of NaCl at 100°C

- Solubility of NaCl at 100°C ≈ 39.2 g/100g water
- 35 g < 39.2 g → Unsaturated

- Answer: Unsaturated

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✔ Final Answers Summary:

| Question | Answer |
|--------|--------|
| 11 | 39.2 g |
| 12 | 148 g |
| 13 | 144 g |
| 14 | 60°C |
| 15 | 60°C |
| 16a | Yes |
| 16b | 89 g |
| 17 | 40 g |
| 18 | 85 g |
| 19 | ~11 g |
| 20a | Supersaturated |
| 20b | Unsaturated |
| 20c | Supersaturated |
| 20f | Saturated |
| 20g | Unsaturated |
| 20h | Unsaturated |

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📌 Notes:

- These answers are based on standard solubility data. If you have a specific solubility curve (e.g., from a textbook or lab sheet), values may vary slightly.
- For compounds like Ce₂(SO₄)₃, solubility is low and often decreases with increasing temperature — unusual behavior.
- Always check whether the solution is unsaturated (< solubility), saturated (= solubility), or supersaturated (> solubility, unstable).

Let me know if you'd like a visual explanation or help interpreting a solubility curve!