Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2008

  • question_answer
    A steady current of 1.5 A flows through a copper voltameter for 10 min. If the electrochemical equivalent of copper is \[30\times {{10}^{-5}}g\,{{C}^{-1}},\]the mass of copper deposited on the electrode will be

    A) \[0.40\,g\]                                          

    B) \[0.50\,g\]

    C) \[0.67\,g\]                                          

    D) \[0.27\,g\]

    Correct Answer: D

    Solution :

    Key Idea Apply first law of electrolysis during deposition of charge on an electrode through electrolysis. If m is the mass of a substance deposited or liberated at an electrode during electrolysis when a charge q passes through electrolyte, then according to Faraday's first law of electrolysis,                 \[m\propto q\] or            \[m=zq\] where z is a constant of proportionality and is called electrochemical equivalent (ECE) of the the substance. If an electric current I flows through the electrolyte, then                 \[q=It\] \[\therefore \]  \[m=zit\] Here,  \[i=1.5A,\] \[t=10\min =10\times 60s,\]                 \[z=30\times {{10}^{-5}}g{{C}^{-1}}\] Hence, mass of copper deposited on the electrode                 \[m=30\times {{10}^{-5}}\times 1.5\times 10\times 60\]                 \[=27\times {{10}^{-2}}=0.27g\]


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