Calculate the work of expansion when 100g of water is electrolysed at a constant pressureof1 atm and temperature of 25^(@)C.

Calculate the work of expansion when 100g of water is electrolysed at

1.	Calculate the work of expansion when 100g of water is electrolysed at a constant pressureof1 atm and temperature of 25^(@)C.
Answer» Solution :Electrolysis ofwater takes placeas`:2H_(2)O() rarr 2H_(2)(g) +O_(2)(g)` Thus, 2 moles of `H_(2)O, i.e., 2 XX 18 = 36 g ` of `H_(2)O` on electrolys is produce 2 moles of `H_(2)` gas and one mole of `O_(2)` gas, i.e., totla3 moles of the GASES `:. `100 g of water will produce gases `= (3)/( 36) xx 100= 8.33 ` moles Volume OCCUPIED by 8.33 moles ofgases at `25^(@)C` and 1 atm pressure is given by `V = ( nRT)/( P) ((8.33 "mole") ( 0.0821L atmK^(-1) mol^(-1)) ( 298K))/( 1 atm)= 203.8 L` Taing the volume of liquid water as negligible ( being 100 mL`= 0.1 L ) , DeltaV = 203.8 L` `:. Ww= - P_(ext) DeltaV =- 1 atm xx203.8 L= - 203.8 L atm= - 203. 8 xx 101.3 J= - 20.6 kJ`