A student titrates 25.0 mL of 0.100 M acetic acid ( ) with 0.100 M NaOH at 25 °C
CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A student titrates 25.0 mL of 0.100 M acetic acid (Ka=1.8×10−5) with 0.100 M NaOH at 25 °C. The equivalence-point pH is measured to be about 8.7. Four common indicators and their transition ranges are shown below.
• Methyl orange: 3.1–4.4
• Bromocresol green: 3.8–5.4
• Phenolphthalein: 8.3–10.0
• Thymol blue (first transition): 1.2–2.8
Which indicator should the student select to minimize indicator error when locating the equivalence point?
(a) Bromocresol green
(b) Methyl orange
(c) Phenolphthalein
(d) Bromothymol blue