# In electrolysis of water, why is the volume of gas collected over one electrode double the volume of gas collected over the other electrode?

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by sharmaSamra6

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by sharmaSamra6

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H2O ------------------------------> H2 + 1/2O2

the electrolysis of one mole water produce one mole of H2 and half mole O2. at the same condition (temperature, pressure) from ideal gas equation

PV = nRT where R is gas constant

apply for Hydrogen:

PV1 = RT ----------------------(1)

apply for Oxygen:

PV2 = RT/2 --------------------------(2)

(1)÷(2)

V1/V2 = 2

hence in the electrolysis of water volume of gas over one electrode is double the volume of gas collected over other electrode.

since water contains 2 atoms of hydrogen & one atom of oxygen. so hydrogens volume is =2(volume of oxygen produced)