902: Solubility Part 1: Solubility Curves Thinking about solubility, explain why the temperatures on the graph only go from 0°C to 100°C? Which substance is most soluble at 5°C? Which two substances have the same solubility at 80°C? Which substance’s solubility changes the most from 20°C to 70°C? Think: Slope! Which substance’s solubility changes the least from 0°C to 100°C? Think: Slope. What is the solubility of potassium nitrate at 50°C? At what temperature does potassium iodide have a solubility of 150 g/100 cm^3 water? Note: 1 cm^3 = 1 mL You have a solution of sodium nitrate containing 140 g in 100 mL H2O at 65°C. Is the solution saturated, unsaturated, or supersaturated? You have a solution of potassium chlorate containing 4 g at 65°C. How many additional grams of solute must be added to it to make the solution saturated (assume in 100 mL water)? If you have 200 g of NaNO3 dissolved in 200 mL of water at 35°C, is the solution saturated, unsaturated, or supersaturated? Note: That’s double the solvent.
902: Solubility Part 1: Solubility Curves Thinking about solubility, explain why the temperatures on the graph only go from 0°C to 100°C? Which substance is most soluble at 5°C? Which two substances have the same solubility at 80°C? Which substance’s solubility changes the most from 20°C to 70°C? Think: Slope! Which substance’s solubility changes the least from 0°C to 100°C? Think: Slope. What is the solubility of potassium nitrate at 50°C? At what temperature does potassium iodide have a solubility of 150 g/100 cm^3 water? Note: 1 cm^3 = 1 mL You have a solution of sodium nitrate containing 140 g in 100 mL H2O at 65°C. Is the solution saturated, unsaturated, or supersaturated? You have a solution of potassium chlorate containing 4 g at 65°C. How many additional grams of solute must be added to it to make the solution saturated (assume in 100 mL water)? If you have 200 g of NaNO3 dissolved in 200 mL of water at 35°C, is the solution saturated, unsaturated, or supersaturated? Note: That’s double the solvent.
The Correct Answer and Explanation is:
Here are the answers to your solubility curve questions, followed by a detailed explanation:
✅ Answers
- Why do the temperatures on the graph only go from 0°C to 100°C?
Because 0°C is the freezing point and 100°C is the boiling point of water under standard atmospheric pressure. Solubility curves are typically plotted within this range to represent conditions where water remains in the liquid state. - Which substance is most soluble at 5°C?
Potassium iodide (KI) is the most soluble at 5°C. - Which two substances have the same solubility at 80°C?
Potassium chlorate (KClO₃) and sodium chloride (NaCl) have the same solubility at 80°C. - Which substance’s solubility changes the most from 20°C to 70°C?
Potassium nitrate (KNO₃) shows the greatest change in solubility over this temperature range. - Which substance’s solubility changes the least from 0°C to 100°C?
Sodium chloride (NaCl) exhibits the least change in solubility over this temperature range. - What is the solubility of potassium nitrate at 50°C?
Approximately 125 g per 100 mL of water. - At what temperature does potassium iodide have a solubility of 150 g/100 mL water?
Approximately 60°C. - You have a solution of sodium nitrate containing 140 g in 100 mL H₂O at 65°C. Is the solution saturated, unsaturated, or supersaturated?
Supersaturated. - You have a solution of potassium chlorate containing 4 g at 65°C. How many additional grams of solute must be added to it to make the solution saturated (assume in 100 mL water)?
Approximately 26 g more are needed to reach saturation. - If you have 200 g of NaNO₃ dissolved in 200 mL of water at 35°C, is the solution saturated, unsaturated, or supersaturated?
Saturated.
🧪 Explanation
Solubility curves illustrate how the solubility of substances varies with temperature. The temperature range of 0°C to 100°C is standard because it encompasses the liquid phase of water under normal atmospheric conditions, ensuring consistent and practical observations.
At lower temperatures, such as 5°C, potassium iodide (KI) demonstrates high solubility, making it the most soluble substance at that temperature. As temperature increases, the solubility of most solids in water also increases. For instance, potassium nitrate (KNO₃) shows a significant increase in solubility between 20°C and 70°C, indicating a steep slope on its solubility curve. Conversely, sodium chloride (NaCl) exhibits minimal change in solubility across the 0°C to 100°C range, reflecting a relatively flat curve.
At 50°C, potassium nitrate has a solubility of approximately 125 g per 100 mL of water. Potassium iodide reaches a solubility of 150 g per 100 mL at around 60°C.
When evaluating solution saturation:
- A solution with 140 g of sodium nitrate in 100 mL of water at 65°C is supersaturated, as it contains more solute than the solubility limit at that temperature.
- A solution with 4 g of potassium chlorate at 65°C requires an additional 26 g to become saturated, totaling 30 g per 100 mL.
- Dissolving 200 g of sodium nitrate in 200 mL of water at 35°C results in a saturated solution, as the solubility at that temperature is approximately 100 g per 100 mL.
Understanding these concepts is crucial for predicting solubility behavior and preparing solutions with desired concentrations.
