Acid–alkali indicators
4 marks · NormalA student tests four solutions using different indicators. Their observations are shown below.
| Solution | Litmus | Methyl Orange | Universal Indicator |
|---|---|---|---|
| A | blue | yellow | blue |
| B | red | red | red |
| C | purple | orange | green |
| D | blue | yellow | green |
Complete the table below by identifying the likely pH or classification (acidic, neutral, or alkaline) for each solution.
| Solution | pH/classification |
|---|---|
| A | |
| B | |
| C | |
| D |
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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Also accept: Accept 'alkaline', 'acidic', 'neutral' as correct
Common mistakes: Confusing methyl orange yellow with acid
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Correctly classifies Solution A as alkaline (or pH>7).
B2 · 1 mark · Correctly classifies Solution B as acidic (or pH<7).
B3 · 1 mark · Correctly classifies Solution C as neutral (or pH 7).
B4 · 1 mark · Correctly classifies Solution D as neutral or alkaline (accept either if justified by colours, but green universal indicator is neutral).
Worked solution
| Solution | pH/classification |
|---|---|
| A | alkaline |
| B | acidic |
| C | neutral |
| D | neutral |