Factors Affecting Solubility

Active learning helps Year 11 students grasp solubility factors because hands-on experiments make abstract concepts like kinetic energy and Henry’s Law visible. Students see temperature and pressure effects with their own eyes, which builds durable understanding beyond memorizing graphs or rules.

• Year 11
• Chemistry
• 4 activities
• 25 min–50 min

Learning Objectives

1. Calculate the solubility of a given solute at a specific temperature using provided data.
2. Explain the relationship between temperature and the solubility of ionic solids and gases, citing particle kinetic energy.
3. Analyze the effect of pressure on the solubility of gases using Henry's Law.
4. Compare and contrast the influence of surface area and stirring on the rate of dissolution versus the equilibrium solubility.
5. Design a simple experiment to test the effect of one factor (temperature, surface area, or stirring) on the solubility of a common salt.

Stations Rotation

⏱ 50 min·Small Groups

Temperature Series: Solid Solubility

Prepare water baths at 20°C, 40°C, and 60°C. Students add excess salt to equal volumes of water, stir for 5 minutes, then filter and evaporate to find dissolved mass. Groups plot solubility vs. temperature and compare solids like sugar and salt.

Prepare & details

Explain how temperature affects the solubility of solids and gases.

Facilitation Tip: During Temperature Series: Solid Solubility, have students record mass dissolved at each temperature on a shared class chart to build a collective solubility curve.

Setup: Tables/desks arranged in 4-6 distinct stations around room

Materials: Station instruction cards, Different materials per station, Rotation timer

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Stations Rotation

⏱ 30 min·Pairs

Pressure Test: Gas Solubility

Use sealed syringes with water and CO2 tablets at different plunger pressures. Students measure volume of dissolved gas by displacement after shaking. Record data and discuss Henry's Law application.

Prepare & details

Analyze the effect of pressure on the solubility of gases.

Facilitation Tip: During Pressure Test: Gas Solubility, demonstrate the gas collection setup before students begin to prevent leaks and ensure consistent pressure readings.

Setup: Tables/desks arranged in 4-6 distinct stations around room

Materials: Station instruction cards, Different materials per station, Rotation timer

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Stations Rotation

⏱ 35 min·Small Groups

Surface Area Race: Dissolution Rate

Provide whole and crushed antacid tablets. Drop into identical water volumes, time full dissolution with and without stirring. Groups tabulate results and graph rate differences.

Prepare & details

Predict how stirring and surface area influence the rate of dissolution.

Facilitation Tip: During Surface Area Race: Dissolution Rate, provide identical solute masses but different surface areas to make the rate difference obvious.

Setup: Tables/desks arranged in 4-6 distinct stations around room

Materials: Station instruction cards, Different materials per station, Rotation timer

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Stations Rotation

⏱ 25 min·Pairs

Stirring Speed Comparison

Dissolve identical sugar amounts in water with slow, medium, and fast stirring. Use stopwatches to record time to clear solution. Analyze how agitation affects particle collision frequency.

Prepare & details

Explain how temperature affects the solubility of solids and gases.

Facilitation Tip: During Stirring Speed Comparison, use timers at each stirring speed so students quantify how stirring affects rate without altering final solubility.

Setup: Tables/desks arranged in 4-6 distinct stations around room

Materials: Station instruction cards, Different materials per station, Rotation timer

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Teaching This Topic

Teach this topic by first establishing the difference between rate and equilibrium solubility. Use analogies students know, like sugar dissolving faster in hot tea but not more sugar dissolving at higher altitude. Avoid rushing through Henry’s Law; let students discover gas behavior through their own pressure tests to build ownership of the concept. Research suggests students retain this better when they test predictions rather than just observe demonstrations.

What to Expect

Successful learning looks like students explaining why temperature increases solid solubility but decreases gas solubility, citing data from their experiments. They should also distinguish between factors that affect rate (stirring, surface area) and those that change equilibrium solubility (temperature, pressure for gases).

Watch Out for These Misconceptions

Common Misconception

During Temperature Series: Solid Solubility, watch for students assuming all solutes behave like table salt, ignoring gas solubility trends.

What to Teach Instead

After the activity, ask groups to present their findings on both solids and gases, highlighting the opposite trends and plotting the data on a shared graph to address the misconception directly.

Common Misconception

During Pressure Test: Gas Solubility, watch for students applying solid solubility rules to gases.

What to Teach Instead

Ask students to predict what happens to a solid’s solubility when pressure increases, then test their hypothesis with a solid sample to show no change, reinforcing the distinction.

Common Misconception

During Surface Area Race: Dissolution Rate, watch for students believing that crushing a solute increases the final amount dissolved.

What to Teach Instead

Have students measure and compare the final mass dissolved for both crushed and whole samples, then discuss why the rate differs but the saturation point remains the same.

Assessment Ideas

Exit Ticket

After Temperature Series: Solid Solubility, give students a solubility curve for potassium nitrate and ask them to: 1. Identify solubility at 40°C, 2. Determine if 70g in 100g water at 30°C is saturated, unsaturated, or supersaturated, and explain why based on their experiment data.

Quick Check

During Pressure Test: Gas Solubility, ask students to predict whether solubility will increase or decrease in three scenarios: heating a solid, cooling a gas, and increasing pressure on a gas, then justify their answers using the principles they tested.

Discussion Prompt

After Stirring Speed Comparison, facilitate a class discussion using the prompt: 'Imagine you are a chemist designing a process to remove dissolved gases from wastewater. What factors would you manipulate, and why, to achieve the lowest possible gas concentration?' Have students reference their pressure and temperature findings to support their choices.

Extensions & Scaffolding

• Challenge early finishers to design a process that maximizes gas solubility using only pressure and temperature controls, then present their method to the class.
• For students who struggle, provide pre-measured solute samples and guide them to plot their data point by point on a class solubility graph.
• Deeper exploration: Have students research real-world applications, such as how soda makers use pressure to keep CO2 dissolved, and connect their findings to the principles they tested.

Key Vocabulary

Solubility	The maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature and pressure, forming a saturated solution.
Saturated Solution	A solution that contains the maximum amount of solute that can be dissolved under given conditions; additional solute will not dissolve.
Henry's Law	A law stating that the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid.
Rate of Dissolution	The speed at which a solute dissolves in a solvent, influenced by factors like surface area and stirring, but not the final equilibrium solubility.