Test-exam 2

Voltmeter zn znso4aq crno33 under standard condition

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Unformatted text preview: cell. Voltmeter Zn ZnSO4(aq) Cr(NO3)3 () Under standard condition which of the following is true? a. The electrons flow from the cathode to the anode. b. The electrons flow from the zinc electrode to the chromium electrode.* c. The potassium ions in the salt bridge flow to the zinc cell. d. The chromium metal, Cr(s), is oxidized. e. The zinc metal, Zn(s), is reduced. Ans. a. Wrong. For Votaic cell electrons flows from anode to cathode. b. Correct. From the table, Zn2+ 2e- → Zn(s) -0.76V while Cr3+ + 3e- → Cr(s) -0.74V. Therefore, zinc direction should be switched and zinc is the anode. 2 c. Wrong. The zinc electrode produces more and more positive ions. To keep Votaic cell electrically neutral, the chloride ions in the salt bridge will have to move to the zinc cell, not potassium ions. d. Wrong. See explanation for a. e. Wrong. See explanation for a. 4. Solid sodium oxalate, ionic reaction is Na2C2O4 ( s) (FW = 133.998 g/mol) can be used as a primary standard for determining the concentration of potassium permanganate, KMnO4 (FW = 158.0...
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This note was uploaded on 03/03/2011 for the course CHEM 100A taught by Professor Dai during the Spring '06 term at UCSD.

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