[填空题]
Commercial vinegar contains a small percentage of ethanoic acid. A stu sk vden2lkt(2) i2s1jdent /zw;pd1d25gq,*aj m o6j5g/jdv s qq 2z4uj wiwishes to determine the concentration of ethanoic acid in vinegar. She titrates a solution of ethanoic acid against a standard solution of potassium hydroxide of concentratiojjq w /;dzqv*jg/62 wgmp5z5 2i4adj odqsu, 1n 8.0 ×10$^{-4}$mol dm$^{-3}$.The equation for the reaction is:
$CH_3COOH$(aq)+KOH(aq)→$CH_3COOK$(aq)+$H_2O$(l)
A volume of 25.0 cm$^3$ of vinegar was diluted with distilled water and made up to a volume of 250.0 cm$^3$ ina volumetric flask. A burette was filled with the diluted solution.
25.0 cm$^3$ of potassium hydroxide solution was added to a conical flask and three drops of phenolphthalein indicator added.
1.Ethanoic acid is considered a weak acid. Define the term ‘weak acid’.
2.The results of the titration are shown in the table below:
Trial is 1 ;Volume of Titre(cm$^3$) is 21.0
Trial is 2 ;Volume of Titre(cm$^3$) is 21.2
Trial is 3 ;Volume of Titre(cm$^3$) is 20.8
2.1.Using section 22 (Section 18- 2025 Syllabus) of the IB data booklet, identify the color at the endpoint,is .
2.2.Calculate the concentration of dilute ethanoic acid.
2.3.Calculate the concentration of ethanoic acid in vinegar.
c= ×($10^{-3}$)mold m$^{-3}$
Important note: The section numbers mentioned in the video solution are specific to the 2024 syllabus.
You can refer to the question stem to find the section numbers in the 2025 syllabus.
