Solutions & Dissolved Particles — Investigation · Physical Science: Chemistry, Grade 11
Study saturation, concentration, conductivity, and particle-count effects.
Solubility and Saturation
Investigate
Does an added salt mass necessarily dissolve completely?
Use two dedicated sessions: first define the model, boundary, variables and comparison, then collect suitable records or analyze the complete supplied-data route; second complete calculations/graphs, compare alternatives, revise and prepare the report. Extend collection time where needed. Supplied-data work does not certify supervised laboratory minutes or mandated investigations.
Materials
- Labeled table salt,room-temperature water
- Small containers,balance if available
- Provided-data option
Before you begin
Use only the listed household materials or analyze the supplied data. An adult should review setup. No flames, strong acids/alkalis, unknown chemicals, household mains, radiation sources, or high-speed projectiles are needed. Keep food-study materials separate from eating and wash hands afterward.
Plan a fair test
Hold water mass 100 g andtemperature 20°C fixed; vary added salt. Use modeled solubility 36 g/100 g water.
Method
- Write a prediction and the physical/chemical mechanism behind it.
- Draw the setup or system boundary; label variables and units.
- Predict dissolved and undissolved masses for the table.
- If observing, stir gently and wait; do not taste or heat sealed vessels.
- Separate equilibrium amount from time to dissolve and calculate dissolved-particle consequences.
- Record repeated observations where possible; keep original readings and note resolution or uncertainty.
- Write a claim supported by specific numbers, explain the mechanism, and identify one limitation and a next test.
Example data — for analysis when materials are unavailable
Illustrative teaching data, not measurements from a real district laboratory. Analyze these when materials are unavailable and identify them as provided data. Do not claim to have performed a measurement you did not make.
| Salt added(g) | Dissolved(g) | Undissolved(g) |
|---|---|---|
| 20 | 20 | 0 |
| 36 | 36 | 0 |
| 50 | 36 | 14 |
Analyze and explain
- Identify saturated cases.
- What happens if water mass doubles at the same temperature?
- Why would stirring not necessarily change the saturation amount?
- Link the pattern to a labeled particle, structure, energy or amount model from the chapter.
- Distinguish supplied illustrative records from measurements actually collected.
- Identify uncertainty and propose a comparison that would test an alternative explanation.
What a strong explanation includes
- A stated prediction, conditions, and controlled variables or explicit model boundary.
- A labeled table/graph with units, calculations, and attention to repeated values or uncertainty.
- A claim citing numerical evidence and a scientifically accurate mechanism.
- A limitation, alternative explanation, and useful follow-up test.
- Preserve initial reasoning and an evidence-supported revision.
- Check units, species identity, system boundary and physical assumptions.
Parent / teacher guide: discuss after the investigation
36 g and 50 g additions can yield saturated liquid;50 g leaves 14 g solid.200 g water has modeled capacity 72 g. Stirring affects the approach rate rather than fixed-temperature equilibrium solubility; actual values require real measurements. Preserve the original observations, intermediate working and a labeled mechanism. Report the relevant boundary and model assumptions, discuss an alternative explanation, and identify the next useful measurement; do not replace unexpected data with the illustrative record.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.