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An indicator changes colour in the pH range 7.6 – 9.2 - Leaving Cert Chemistry - Question 8 - 2001
Question 8
An indicator changes colour in the pH range 7.6 – 9.2. For which types of acid-base titration would it be suitable?
Worked Solution & Example Answer:An indicator changes colour in the pH range 7.6 – 9.2 - Leaving Cert Chemistry - Question 8 - 2001
Step 1
strong acid-strong base
Answer
The indicator is suitable for titrations between strong acids and strong bases when the pH at the equivalence point is around neutral (pH 7). Since the indicator changes color at pH 7.6 to 9.2, it can effectively signal the endpoint in this type of titration.
Step 2
weak acid-strong base
Answer
In titrations between weak acids and strong bases, the pH at the equivalence point is typically greater than 7, often ranging from pH 8 to pH 10. Therefore, the indicator is also suitable for this type of titration since its color change range includes the typical pH at which the equivalence point occurs.