Solubility Curves Packet - Key - i i 5 sowsrurv CURVES Answer the ... - Free Printable

Let’s solve each question step by step using the solubility curve graph (which we can’t see, but based on standard solubility curves and common textbook problems, we’ll use typical values for KNO₃, NaCl, NH₄Cl, etc., as implied by the questions).

We are told it’s Tuesday, May 12, 2026 — but that doesn’t affect the chemistry. We’re solving solubility problems.

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Question 1: Which salt is least soluble in water at 20°C?

Looking at standard solubility curves:
- At 20°C, NaCl is about 36 g/100g water
- KNO₃ is about 32 g/100g water
- NH₄Cl is about 37 g/100g water
- Ce₂(SO₄)₃ or similar rare earth salts are very low — often <5 g

But since the worksheet mentions “Ce” (cerium sulfate?) and has a line going down with temperature, likely Ce₂(SO₄)₃ is the one that decreases with temp and is very low at 20°C.

In many textbooks, Ce₂(SO₄)₃ is shown to have solubility around 5–8 g/100g water at 20°C, much lower than others.

✔ So answer: Ce₂(SO₄)₃

*(Note: If your graph shows something else, adjust — but this is standard.)*

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Question 2: How many grams of potassium chloride (KCl) can be dissolved in 200 g of water at 80°C?

Standard solubility of KCl at 80°C ≈ 51 g per 100 g water

So for 200 g water → 51 × 2 = 102 g

✔ Answer: 102 grams

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Question 3: At 40°C, how much potassium nitrate (KNO₃) can be dissolved in 300 g of water?

Solubility of KNO₃ at 40°C ≈ 64 g per 100 g water

For 300 g water → 64 × 3 = 192 g

✔ Answer: 192 grams

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Question 4: Which salt has the least change in solubility from 0°C to 100°C?

Look at the slopes:

- NaCl: almost flat — goes from ~35 g at 0°C to ~39 g at 100°C → only +4 g
- KNO₃: steep rise — from ~13 g to ~246 g → huge change
- NH₄Cl: moderate rise — ~30 g to ~75 g
- Ce₂(SO₄)₃: may decrease slightly

✔ So NaCl has the least change.

Answer: Sodium chloride (NaCl)

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Question 5: At 30°C, 90 g of sodium nitrate (NaNO₃) is dissolved in 100 g of water. Is this solution unsaturated, saturated, or supersaturated?

Solubility of NaNO₃ at 30°C ≈ 95 g per 100 g water

You have 90 g → less than 95 g → so it’s unsaturated

✔ Answer: Unsaturated

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Question 6: A saturated solution of potassium chlorate (KClO₃) is formed from one hundred grams of water. If the saturated solution is cooled from 90°C to 60°C, how many grams of precipitate will form?

Solubility of KClO₃:
- At 90°C ≈ 50 g / 100 g water
- At 60°C ≈ 25 g / 100 g water

So when cooled, excess crystallizes out: 50 - 25 = 25 g precipitate

✔ Answer: 25 grams

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Question 7: What amount of solute is dissolved in 150 g of water at 20°C to give a saturated solution? (Assume it's KNO₃ — since not specified, but context suggests KNO₃ from Q3)

Wait — question says “what amount of solute” — but doesn’t specify which! Looking back at original image text (from user upload), it probably refers to potassium nitrate (KNO₃) because previous questions mention it.

At 20°C, KNO solubility ≈ 32 g / 100 g water

For 150 g water → 32 × 1.5 = 48 g

✔ Answer: 48 grams

*(If it were another salt, adjust — but KNO₃ is most likely here.)*

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Question 8: Which salt will lose mass at 10°C if heated to 90°C?

This means: which salt becomes *less* soluble as temperature increases? That would cause precipitation when heated — losing dissolved mass.

Only Ce₂(SO₄)₃ (or cerium sulfate) typically has decreasing solubility with increasing temperature.

Others increase.

✔ Answer: Cerium(III) sulfate (Ce₂(SO₄)₃)

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Question 9: Which salt is most soluble at 10°C?

Check solubilities at 10°C:

- NaCl: ~35 g
- KNO₃: ~20 g
- NH₄Cl: ~33 g
- Ce₂(SO₄)₃: ~5 g
- Maybe CaCl₂ or others? But not listed.

Actually, NaCl is usually highest among common salts at low temps unless CaCl₂ is included — but not mentioned.

Wait — sometimes NH₄Cl is close, but NaCl is still higher.

But let’s double-check: In some graphs, NaCl is ~35, NH₄Cl ~33, KNO₃ ~20, Ce₂(SO₄)₃ ~5.

✔ So NaCl is most soluble at 10°C.

BUT — wait! Some sources show CaCl₂ or LiCl as very soluble even at low temps — but they aren't on this graph probably.

Given options implied by worksheet: NaCl

However — looking again at Question 1, Ce was least soluble — so likely NaCl is highest at low temp.

✔ Final: Sodium chloride (NaCl)

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Question 10: Which salt is least soluble at 90°C?

At high temp:

- KNO₃: very high (~246 g)
- NaCl: ~39 g
- NH₄Cl: ~75 g
- Ce₂(SO₄)₃: maybe ~5 g or less — and possibly decreasing

So Ce₂(SO₄)₃ is still lowest.

✔ Answer: Cerium(III) sulfate (Ce₂(SO₄)₃)

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Now, compiling all answers clearly:

Final Answer:
1. Ce₂(SO₄)₃
2. 102 grams
3. 192 grams
4. Sodium chloride (NaCl)
5. Unsaturated
6. 25 grams
7. 48 grams
8. Cerium(III) sulfate (Ce₂(SO₄))
9. Sodium chloride (NaCl)
10. Cerium(III) sulfate (Ce₂(SO₄)₃)