A direct current power supply of low voltage (less than 10 volts) has lost the m
ID: 508831 • Letter: A
Question
A direct current power supply of low voltage (less than 10 volts) has lost the markings that indicate which output terminal is positive and which is negative. A chemist suggests that the power supply terminals be connected to a pair of platinum electrodes that dip into 0.1-molar KI solution. Which of the following correctly identifies the polarities of the power supply terminals? (A) A gas will be evolved only at the positive electrode. Correct or incorrect? Explanation: (B) A gas will be evolved only at the negative electrode. Correct or incorrect? Explanation: (C) A brown color will appear in the solution near the negative electrode. Correct or incorrect? Explanation: (D) A metal will be deposited on the positive electrode. Correct or incorrect? Explanation: (E) None of the methods above will identify the polarities of the power supply terminals.Explanation / Answer
A direct-current power supply of low voltage (less than 10 volts) has lost the markings that indicate whichoutput terminal is positive and which is negative. A chemist suggests that the power supply terminals beconnected to a pair of platinum electrodes that dip into 0.1-molar KI solution. Which of the following correctly identifies the polarities of the power supply terminals?
(A) A gas will be evolved only at the positive electrode
.(B) A gas will be evolved only at the negative electrode-----answer
.(C) A brown color will appear in the solution near the negative electrode.
(D) A metal will be deposited on the positive electrode
.(E) None of the methods above will identify the polarities of the power supply terminals
explanation
2I- -------> I2 + 2 e-
K+ + e- ----------> K
2K+ ----------> 2 K + + 2 e- --------ANODE
2I2 + 2 e - --------->2I- ---------cathode
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