Question

Assertion :$(H_2+O_2)$ fuel cell gives a constant voltage throughtout its life. Reason: In this fuel cell, $H_2$ reacts with $\stackrel{\ominus }{O}H$ ions, yet the over all$\left[\stackrel{\ominus }{O}H\right]$ does not change.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

FUEL CELLS

It is possible to make batteries in which the reactants are fed continuously to the electrodes. Electrical cells that are designated to convert the free energy from the combustion of fuels such as hydrogen, carbon monoxide or methane directly into electrical energy are called FUEL CELLS. One of the most successful fuel cells uses the reaction of hydrogen with oxygen to form water (fig.). This cells has been used for electric power in the Appollo space programme. The water vapor produced was condensed and added to the drinking water supply for the astronauts.

In the cell (fig.) hydrogen and oxygen are bubbled through a porous carbon electrode into concentrated aqueous sodium hydroxide. Catalysts are incorporated in the electrode. The electrode reactions are :

Anode $2\left[H_2\right(g)+2O{H}^{-}(aq)\to 2H_{2}O(\ell )+2e^{-}]$

Cathode $O_2\left(g\right)+2H_{2}O\left(\ell \right)+4e^{-}\to 4O{H}^{-}\left(aq\right)$

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Overall reaction : $2H_2\left(g\right)+O_2\left(g\right)\to 2H_{2}O\left(\ell \right)$

This cells runs continuously as long as the reactants are supplied.