[填空题]
Commercial vinegar co0utgb abt;do 3 -5a)runtains a smallsxbiwj 2m m 33ocm 2b -tqdzxc5-p)5l6 percentage of ethanoic acid. A student wishes to determine the concentration of ethanoic acid in vinegar. She titrates a6p2cmmq2j )its-c x-5 33dlo5zwx m bb solution of ethanoic acid against a standard solution of potassium hydroxide of concentration 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.
