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Tracking Labeled Salt in a Saturated Bath 4 questions
Tracking Labeled Salt in a Saturated Bath
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A model salt solution is saturated at a fixed temperature and contains undissolved crystals. Some dissolved chloride ions have a stable isotope label. The label distinguishes them in the simulation and does not change how they interact with the salt. The crystals start without the label.
| Measurement | Start | After 20 min |
|---|---|---|
| Mass of undissolved crystals | 3.0 g | 3.0 g |
| Total dissolved salt concentration | Same fixed value | Same fixed value |
| Labeled chloride detected in crystals? | No | Yes |
Question 1
Which process must have occurred to account for the new label in the crystals?
- Labeled chloride left the solution and entered the crystals.
- The crystals released labeled chloride into the solution.
- The isotope label changed the chloride into a different element.
- The crystals increased in total mass.
Question 2
Use the unchanged masses and the label result to explain how ions can keep moving between solid and solution.
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The class repeats the model and adds pure water at the same temperature. It stirs and waits until the solution is saturated again. Some undissolved salt remains.
Question 3
Predict whether the mass of undissolved salt is greater or less after adding the water. Explain what must happen before the solution returns to saturation.
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Question 4
After saturation returns, how does the final concentration compare with the concentration before the water was added? Explain why this does not require the same dissolved amount.
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