[填空题]
Commercial vinegar contains a small percentage of etufx pr bf9n6vv2w16d:n3b ct/hanoic acid. A slv26)8 (sh+g b)sfc pmzvgc y(tudent wishes to determine the concentration of ethanoic acid in vinegar. She titrates a solution of ethanoic acid against a standard )8 6shf)gyvc cs gvml2(b+zp (solution of potassium hydroxide of concentration $8.0\times 10^{-4}\,mol\,dm^{-3}$. The equation for the reaction is:
$CH_3COOH(aq) + KOH(aq) \rightarrow CH_3COOK(aq) + H_2O(I)$
A volume of $25.0\,cm^3$ of vinegar was diluted with distilled water and made up to a volume of $250.0\,cm^3$ in a volumetric flask. A burette was filled with the diluted solution.
$25.0cm^3$ 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
Volume of Titre$(cm^3)$
1
21.0
2
21.2
3
20.8
1.Using section 22 (Section 18- 2025 Syllabus) of the IB data booklet, identify the color at the endpoint.
2.Calculate the concentration of dilute ethanoic acid.
3.Calculate the concentration of ethanoic acid in vinegar. $\times10^{-4}\,mol\,dm^{-3}$
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.
