Question 1

What is NCEA AS 91162 about?

Accepted Answer

In this standard, you'll do practical lab work to identify which ions are dissolved in a solution by following a specific testing procedure. You'll collect data from chemical reactions (like colour changes or precipitates forming), record your observations carefully, and use them to figure out which ions are present. The key is linking what you actually see happen to what ions must be in the solution.

Question 2

What do students need to do for AS 91162?

Accepted Answer

1. Follow a provided lab procedure to test a solution systematically for different ions 2. Make careful observations of what happens during each test (colour changes, precipitates, whether solids dissolve in excess reagent) 3. Record the experimental observations clearly so someone else could understand what you saw 4. Identify which ions are present based on the evidence from your tests 5. Write balanced chemical equations to explain the reactions you observed, including what happens when precipitates dissolve in excess reagent

Question 3

What's the difference between Achieved, Merit, and Excellence for AS 91162?

Accepted Answer

Achieved: You successfully carry out the lab procedure, make observations, and correctly identify which ions are present based on what you actually saw happen. Merit: You justify your ion identifications by writing balanced equations for the precipitation reactions you observed and linking them to your data. Excellence: You comprehensively justify your identifications by recognising and explaining complex ion formation (ions that reform when you add excess reagent), writing balanced equations for these reactions, and showing you understand what's happening beyond just the precipitate forming.

Question 4

What mistakes do students typically make in AS 91162?

Accepted Answer

1. Not recording observations precisely enough — saying 'something happened' instead of describing the exact colour, whether a solid formed, or how a precipitate behaved in excess reagent 2. Identifying ions without linking them back to experimental observations — just guessing which ions are there instead of explaining which test result proved it 3. Writing incomplete or unbalanced equations, or missing equations for complex ion reactions that form when excess reagent is added

Ion identification

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AS91162 — Qualitative Analysis (expired)

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