Questions 11 through 20 of a solubility curve worksheet asking for specific mass and temperature calculations.

Let’s solve each problem step by step. These questions are about solubility — how much of a substance can dissolve in water at different temperatures. We’ll use standard solubility data (from common solubility curves) to answer them.

---

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

→ At 100°C, the solubility of NaCl is about 39 g per 100 g water.
*(Note: NaCl doesn’t change much with temperature — it’s almost flat on the curve.)*

✔ Answer: 39 g

---

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

→ From solubility charts, NaNO₃ at 90°C dissolves about 155 g per 100 g water.

✔ Answer: 155 g

---

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

→ Potassium iodide (KI) at 20°C has a solubility of about 145 g per 100 g water.

✔ Answer: 145 g

---

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

→ KClO₃ solubility:
At 20°C → ~7 g
At 40°C → ~14 g
At 60°C → ~25 g ← This matches!

✔ Answer: 60°C

---

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

→ Ammonium chloride (NH₄Cl):
At 50°C → ~50 g
At 60°C → ~55 g ← Perfect match.

✔ Answer: 60°C

---

16. 89 g NaNO₃ is prepared at 30°C.

a) Will all of the salt dissolve?

→ At 30°C, NaNO₃ solubility is about 95 g per 100 g water.
Since 89 g < 95 g → YES, it will all dissolve.

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

→ Since we’re using 100 g water (assumed unless stated otherwise), and solubility is 95 g, but we only have 89 g → all 89 g dissolves.

✔ Answers:
a) Yes
b) 89 g

---

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

→ First, find solubility at 80°C: NH₄Cl ≈ 65 g per 100 g water
Already dissolved: 25 g
Additional needed = 65 - 25 = 40 g

✔ Answer: 40 g

---

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

→ Potassium nitrate (KNO₃) at 50°C: solubility ≈ 85 g per 100 g water

✔ Answer: 85 g

---

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

→ Cerium(III) sulfate is unusual — its solubility *decreases* with temperature.
At 70°C, solubility is very low — about 5 g per 100 g water (some sources say even less, like 3–5 g).

We’ll go with 5 g as a reasonable estimate for school-level problems.

✔ Answer: 5 g

---

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

We compare given amount to solubility at that temp.

a. 55g of NH₃ at 20°C
→ Wait — NH₃ is ammonia gas. Its solubility is high, but typically measured differently. In most textbooks, for solids, we assume these are solid salts. But NH₃ is not a solid. Let’s check context.

Actually — looking back, question 20a says “NH₃” — but earlier questions were about solids. Probably a typo? Or maybe they mean ammonium compound? But let’s assume it’s correct.

Ammonia (NH₃) at 20°C: solubility is about 52 g per 100 g water (for gas under pressure). So 55g > 52g → could be supersaturated? But gases don’t usually form supersaturated solutions easily.

Wait — perhaps it’s meant to be NH₄Cl? Because in Q15 and Q17 we had NH₄Cl. And 55g at 20°C for NH₄Cl: solubility at 20°C is ~37g → so 55g > 37g → supersaturated.

But the question says “NH₃”. Hmm.

Alternatively, maybe it’s a mistake and should be NaNO₃? No, f is NaNO₃.

Looking at pattern — probably it’s NH₄Cl, since others are solids. Let’s assume typo and it’s NH₄Cl.

So: NH₄Cl at 20°C → solubility ~37g → 55g > 37g → supersaturated

But to be safe — if it really is NH₃ (ammonia), then at 20°C, max solubility is about 52g/100g water → 55g > 52g → still supersaturated (though rare for gases).

I think for consistency with other problems, we’ll treat it as a solid-like behavior.

✔ a. supersaturated

b. 10g of Ce₂(SO₄)₃ at 10°C

→ Cerium sulfate at 10°C: solubility is higher than at 70°C. At 0°C it’s about 20g, at 10°C maybe ~18g? So 10g < 18g → unsaturated

✔ b. unsaturated

c. 125g of KNO₃ at 60°C

→ KNO₃ at 60°C: solubility ≈ 110 g per 100 g water
125g > 110g → supersaturated

✔ c. supersaturated

f. 80g of NaNO₃ at 10°C

→ NaNO₃ at 10°C: solubility ≈ 80 g per 100 g water → exactly saturated

✔ f. saturated

g. 145g of NaNO₃ at 80°C

→ NaNO₃ at 80°C: solubility ≈ 145 g per 100 g water → exactly saturated

✔ g. saturated

h. 35g of NaCl at 100°C

→ NaCl at 100°C: solubility ≈ 39 g per 100 g water
35g < 39g → unsaturated

✔ h. unsaturated

---

Final Answers:

11. 39 g
12. 155 g
13. 145 g
14. 60°C
15. 60°C
16. a) Yes b) 89 g
17. 40 g
18. 85 g
19. 5 g
20. a) supersaturated b) unsaturated c) supersaturated f) saturated g) saturated h) unsaturated