im sure one is bromothymol blue, however im not sure if the other indicator is b
ID: 1086473 • Letter: I
Question
im sure one is bromothymol blue, however im not sure if the other indicator is bromocresol purple or cresol red.
the pH of HCl and NaOH is 7 and the pH of acetic acid with NaOH is 9
Refer to the titration curves for the strong acid HCI (Figure 1, p. P-2) and for the weak acid acetic acid (Figure 2, p. P-3). From one of the Data Sheets in this manual, or from the Table on p. P-5, select two acid-base indicators that would be suitable for replicate titrations of HCl with NaOH but would NOT be suitable for acetic acid with NaOH. (0.5 marks)Explanation / Answer
Bromothymol blue is correct since the equivalence point between HCl and NaOH happens at the PH range.
In the case of the acetic acid titration, by the time the solution reaches ph = 9 the solution will already be blue.
The second indicator is cresol red, this is because the the ph = 7.2 is very close to 7 , in the titration curve you can see that when you reach the equivalence point the ph raises dramatically so the volume required to reach ph = 7.2 vs the one to reach ph = 7 is almost the same
For the aceetic acid, by the time the solution reaches ph = 9 it will already be red and you wont be able to get useful information
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