Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can say what a common ion is and identify one for a given salt and solution. (Guide: “What a common ion does”; Practice Q3)
- I can use Le Châtelier’s principle to explain why a common ion lowers the solubility of a salt. (Guide: “What a common ion does”; Practice Q1)
- I can explain the same effect using Q and K_sp. (Practice Q7(a))
- I can state that K_sp stays constant while the solubility and the other ion’s concentration fall. (Guide: “What changes and what does not”; Practice Q1)
- I can explain why an ion that is not in the K_sp expression does not cause a common-ion effect. (Practice Q3, Q7(b))
Calculation
- I can calculate the molar solubility of a 1:1 salt in a solution containing a common ion. (Practice Q2)
- I can calculate the molar solubility of a 1:2 or 2:1 salt with a common ion, putting the common ion in the right place and power. (Guide: Worked example 1; Practice Q5)
- I can check whether the approximation c + s ≈ c is valid. (Guide: Worked example 1; Practice Q5(b))
- I can calculate K_sp from a solubility or ion concentration measured in a common-ion solution. (Guide: Worked example 2; Practice Q6, Q7(c))
Reasoning and experimental design
- I can explain which of two common ions lowers a salt’s solubility more, using the powers in K_sp. (Guide: Worked example 1; Practice Q3, Q5(c))
- I can explain how using a solution with a common ion instead of pure water changes measured solubility and a calculated K_sp. (Guide: Worked example 2; Practice Q4, Q6(c))
- I can explain why a precipitate is rinsed with a dilute solution containing a common ion. (Guide: Worked example 3)
All ticked? Move on to Topic 8.1, Introduction to Acids and Bases, or return to the course roadmap.