The graph shows the colour ranges of the acid-base indicators methyl orange, bromothymol blue and phenolphthalein - HSC - SSCE Chemistry - Question 6 - 2001 - Paper 1
Question 6
The graph shows the colour ranges of the acid-base indicators methyl orange, bromothymol blue and phenolphthalein.
Methyl orange: red
Bromothymol blue: yellow
Pheno... show full transcript
Worked Solution & Example Answer:The graph shows the colour ranges of the acid-base indicators methyl orange, bromothymol blue and phenolphthalein - HSC - SSCE Chemistry - Question 6 - 2001 - Paper 1
Step 1
Identify the pH range for methyl orange.
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Answer
Methyl orange is yellow at a pH range of 3.1 to 4.4, indicating that the solution must be above this range.
Step 2
Identify the pH range for bromothymol blue.
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Answer
Bromothymol blue is blue at a pH range of 6.0 to 7.6, meaning the solution must be higher than 6.0.
Step 3
Identify the pH range for phenolphthalein.
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Answer
Phenolphthalein is colourless below pH 8.2, indicating that the pH must be less than 8.2.
Step 4
Determine the combined pH range.
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Answer
From the information gathered, the pH must be above 6.0 (bromothymol blue) and below 8.2 (phenolphthalein). Therefore, the pH range of the solution is 6.0 to 8.2.
