Here are the answers to the questions on the worksheet, based on the solubility curve provided.
1. Define solubility.
Solubility is the maximum amount of a substance (solute) that can dissolve in a specific amount of solvent at a certain temperature.
2. Using the solubility curve below, answer the given questions.
I. What is the solvent in this solubility curve?
Water ($H_2O$).
*(Reasoning: The y-axis label says "per 100 g $H_2O$".)*
II. Saturation points are given per how much of the solvent?
100 grams.
III. What is the saturation point of $NaNO_3$ at 10°C, 40°C, & 80°C?
*
10°C = 80 g
*
40°C = 105 g *(The line is halfway between 100 and 110)*
*
80°C = 150 g
IV. How much $NH_3$ can you dissolve in water at 10°C, 30°C, & 90°C?
*
10°C = 70 g
*
30°C = 40 g
*
90°C = 10 g
V. Which salt is the least soluble in water?
$KClO_3$ (Potassium chlorate).
*(Reasoning: At room temperature (around 20-25°C), its line is the lowest among all the salts listed. While gases like $SO_2$ are lower, they are not salts.)*
VI. How many grams of potassium chloride can be dissolved in 200 g of water at 80 °C?
100 g
*(Reasoning: Find KCl on the graph at 80°C. The value is 50 g per 100 g of water. Since you have 200 g of water, you multiply by 2: $50 \times 2 = 100$.)*
VII. At 40 °C, how much potassium nitrate will be dissolved in 300 g of water?
195 g
*(Reasoning: Find $KNO_3$ at 40°C. The value is roughly 65 g per 100 g of water. Since you have 300 g of water, multiply by 3: $65 \times 3 = 195$.)*
VIII. Which salt shows the least change in solubility from 0° to 100° C?
$NaCl$ (Sodium chloride).
*(Reasoning: Its line is almost flat/horizontal compared to the others.)*
IX. Which substance shows a decrease in solubility from 0° to 100° C?
$NH_3$, $HCl$, and $SO_2$.
*(Reasoning: These are the lines that go downwards as temperature increases. Usually, gases behave this way.)*
X. At 30 °C, 90 g of sodium nitrate is dissolved in 100 g water. Is this solution saturated, unsaturated, or supersaturated?
Unsaturated
*(Reasoning: Look at the $NaNO_3$ line at 30°C. The solubility limit is about 95 g. Since you only have 90 g dissolved, it is below the limit, meaning it is unsaturated.)*
Parent Tip: Review the logic above to help your child master the concept of solubility chart worksheet.
