Solubility Curve worksheet with questions on solubility of salts at different temperatures and related calculations.

Problem Analysis:

The task involves analyzing a solubility curve (Table C) to answer several questions related to the solubility of different substances in water at various temperatures. The solubility curve provides data on how much solute can dissolve in 100 g of water at different temperatures.

Solubility Curve Explanation:

- The solubility curve shows the maximum amount of solute (in grams) that can dissolve in 100 g of water at a given temperature.
- If a solution contains more solute than the solubility curve indicates, it is saturated or supersaturated.
- If a solution contains less solute than the solubility curve indicates, it is unsaturated.

Questions and Solutions:

#### 1. Which salt is least soluble in water at 20°C?
- From Table C, we need to identify the substance with the lowest solubility at 20°C.
- At 20°C:
- $ \text{KCl} $: ~34 g
- $ \text{NaCl} $: ~36 g
- $ \text{KNO}_3 $: ~32 g
- $ \text{NH}_4\text{Cl} $: ~37 g
- $ \text{CaSO}_4 $: ~0.2 g
- $ \text{CaCO}_3 $: ~0.01 g
- $ \text{BaSO}_4 $: ~2.5 × 10⁻⁴ g
- $ \text{AgCl} $: ~0.0015 g

- The least soluble salt at 20°C is $ \text{AgCl} $ (0.0015 g).

Answer: 14. AgCl

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#### 2. At 20°C, 90 g of sodium iodide is dissolved in 100 g of water. Is the solution saturated, unsaturated, or supersaturated?
- From Table C, the solubility of $ \text{NaI} $ at 20°C is approximately 180 g per 100 g of water.
- Since 90 g of $ \text{NaI} $ is dissolved in 100 g of water, and this is less than the solubility limit of 180 g, the solution is unsaturated.

Answer: 12. Unsaturated

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#### 3. Which compound shows the greatest change in solubility between 20°C and 80°C?
- We need to calculate the change in solubility for each compound between 20°C and 80°C.
- From Table C:
- $ \text{KCl} $: 34 g (20°C) → 56 g (80°C); Change = 56 - 34 = 22 g
- $ \text{NaCl} $: 36 g (20°C) → 39 g (80°C); Change = 39 - 36 = 3 g
- $ \text{KNO}_3 $: 32 g (20°C) → 246 g (80°C); Change = 246 - 32 = 214 g
- $ \text{NH}_4\text{Cl} $: 37 g (20°C) → 77 g (80°C); Change = 77 - 37 = 40 g
- $ \text{CaSO}_4 $: 0.2 g (20°C) → 0.2 g (80°C); Change = 0 g
- $ \text{CaCO}_3 $: 0.01 g (20°C) → 0.01 g (80°C); Change = 0 g
- $ \text{BaSO}_4 $: 2.5 × 10⁻⁴ g (20°C) → 2.5 × 10⁻⁴ g (80°C); Change = 0 g
- $ \text{AgCl} $: 0.0015 g (20°C) → 0.0015 g (80°C); Change = 0 g

- The compound with the greatest change in solubility is $ \text{KNO}_3 $ (214 g).

Answer: 10. KNO₃

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#### 4. Which salt is most soluble at 80°C?
- From Table C, we need to identify the substance with the highest solubility at 80°C.
- At 80°C:
- $ \text{KCl} $: ~56 g
- $ \text{NaCl} $: ~39 g
- $ \text{KNO}_3 $: ~246 g
- $ \text{NH}_4\text{Cl} $: ~77 g
- $ \text{CaSO}_4 $: ~0.2 g
- $ \text{CaCO}_3 $: ~0.01 g
- $ \text{BaSO}_4 $: ~2.5 × 10⁻⁴ g
- $ \text{AgCl} $: ~0.0015 g

- The most soluble salt at 80°C is $ \text{KNO}_3 $ (246 g).

Answer: 10. KNO₃

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#### 5. How many grams of potassium chloride can be dissolved in 200 g of water at 20°C if 10% of the water evaporates?
- Initially, 200 g of water is available.
- If 10% of the water evaporates, the remaining water is:
$$
200 \, \text{g} \times (1 - 0.10) = 200 \, \text{g} \times 0.90 = 180 \, \text{g}
$$
- From Table C, the solubility of $ \text{KCl} $ at 20°C is 34 g per 100 g of water.
- For 180 g of water, the amount of $ \text{KCl} $ that can dissolve is:
$$
\frac{34 \, \text{g}}{100 \, \text{g}} \times 180 \, \text{g} = 61.2 \, \text{g}
$$

Answer: 61.2 g

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#### 6. At 40°C, how much potassium iodide can be dissolved in 200 g of water to form a saturated solution?
- From Table C, the solubility of $ \text{KI} $ at 40°C is approximately 140 g per 100 g of water.
- For 200 g of water, the amount of $ \text{KI} $ that can dissolve is:
$$
\frac{140 \, \text{g}}{100 \, \text{g}} \times 200 \, \text{g} = 280 \, \text{g}
$$

Answer: 280 g

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#### 7. Define the following terms:
- Soluble and insoluble: A substance is soluble if it dissolves readily in a solvent (e.g., water), and insoluble if it does not dissolve significantly.
- Miscible and immiscible: Two liquids are miscible if they can mix in all proportions to form a homogeneous solution, and immiscible if they do not mix (e.g., oil and water).
- Diluted and concentrated: A solution is diluted if it has a low concentration of solute, and concentrated if it has a high concentration of solute.

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#### 8. What term describes a solution in which dissolved solute is in equilibrium with the solid solute?
- A solution in which dissolved solute is in equilibrium with the solid solute is called a saturated solution.

Answer: Saturated solution

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Final Answers:

1. 14. AgCl
2. 12. Unsaturated
3. 10. KNO₃
4. 10. KNO₃
5. 61.2 g
6. 280 g
7. Definitions provided above
8. Saturated solution

Boxed Final Answer:
$$
\boxed{14, 12, 10, 10, 61.2, 280, \text{Definitions provided}, \text{Saturated solution}}
$$