Distinguish between the endpoint and the equivalence point. The endpoint is at n
ID: 834858 • Letter: D
Question
Distinguish between the endpoint and the equivalence point. The endpoint is at neutrality and the equivalence point is at the pKa of the weak acid. The equivalence point is at neutrality and the endpoint is at the pKa of the weak acid. The equivalence point is where an observable physical change occurs and the endpoint is where the moles of titrant are equal to the moles of analyte. The endpoint is where an observable physical change occurs and the equivalence point is where the moles of titrant are equal to the moles of analyte. Why is it not practical to titrate an acid or base that is too dilute or too weak? It becomes increasingly difficult to observe the end of the titration as concentration and / or the strength of the acid / base decrease. CO2 from the atmosphere will increase the basicity of the solution. Just one drop will complete the titration, a volume too small to rely on. The experimental error in the buret is too large to obtain appropriate accuracy. (Use this information for questions 3-5.) Consider the titration of 20.00 mL 0.100 M hydroxyacetic acid with 0.050 M KOH. How many mL of KOH must be added to reach the equivalence point? 1.0 mL 1.00 mL 40 mL 0.025 mL What is the pH after 10.00 mL of KOH has been added? 3.71 3.35 4.43 3.86 What is the pH at the equivalence point? 8.18 7.00 10.17 3.832 What color do you expect to observe for cresol purple indicator at pH = 1.0, 2.0 and 3.0 respectively? red - orange red - orange - yellow orange - yellow yellow - orange - red Which of the following is true? Metal ions are Lewis bases AND EDTA is a Lewis acid. Metal ions are Lewis bases AND EDTA is an electron pair donor. Metal ions are Lewis acids AND EDTA is a Lewis base. Metal ions are Lewis bases AND EDTA is an electron pair acceptor. EDTA is Tetradentate Hexadentate Tridentate Pentadentate For EDTA to be most effective as a chelating agent, the solution must be Very dilute Strongly acidic Strongly basic NeutralExplanation / Answer
1-D
2-A
3-C
4-b
5-b
6-d
7-c
8-b
9-b