Final Exam CHEM 3811 18. Which of the following is NOT an example of reference e

Question

Final Exam CHEM 3811 18. Which of the following is NOT an example of reference electrode? c. SHEd. SCE a. ISE b. Ag/Agci 19. Given that the molarity and activity coefficient of a solution of K' are 0.050 M and 0.805, find the activity of the solution. c. 0.062 MM d. 0.755 M a 0.855 M 20. Which of the following statements about activity coefficient is FALSE? b. 0.040 M a. Activity coefficient increases with decreasing ionic strength. b. Activity coefficient decreases with increasing magnitude of charge. c. Activity coefficient of neutral molecules is assumed unity (1). d. Activity coefficient depends on the sign of charge. 21. Which of the following statements about errors is FALSE? a. systematic crror is also known as determinate error b. random errors are always present and cannot be corrected. c. systematic errors are always present and cannot be corrected. d. precise measurements are not always accurate. 22. Which of the following statements about EDTA is TRUE? a. EDTA has six pKa values. b. EDTA is hexabasic. c. EDTA binds through two N and four O atoms. d. both (a) and (c) are correct. 23. What is the pH of a 0.0055 M solution of H SO4? a. 1.96 b. 2.26 c. 12.04 d. 11.74 24. What is the pH of a solution prepared by adding 0.256 g KOH to water to make 500.0 ml solution? a. 2.341 b. 2.040 c. 2.642 d. 11.96 25. When AlBrs dissolves in water, the pH of the solution would....... a. increaseb. decrease c.remain the same d. more information is needed

Explanation / Answer

18) SHE (Standard Hydrogen electrode), SCE (Saturated calamel Electrode) , Ag/AgCl are the examples of rederence electrode.

option a ISE (Ion selective Electrode) is used to measure the ion activity is not a reference electrode.

19) Molarity = 0.05 M, activity coefficient = 0.805

    activity = molarity * activity coeffcient = 0.05 M * 0.805 = 0.040 M - option b

20) option d

    reason: activity coefficient depends on the magnitude of the charge but not on the sign.

21) option C

Reason: Systematic errors can be eliminated through proper training and guidance.

answering only first four due to time constraint and policy guidelines

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