InterviewSolution
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InterviewSolution
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(a)For the reaction : `2AgCl (s) + H_(2)(g) ` (1 atm) ` to 2 Ag(s) + 2H^(+) (0.1M) + 2Cl^(-) (0.1M) , DeltaG^(@) = -43600J` at `25^(@)`C. Calculate the e.m.f. of the cell . [log `10^(-n) = -n`]. (b) Define fuel cell and write its two advantages. |
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Answer» (a) `2AgCl(s) + H_(2)(g)` (1 atm) `to 2Ag(s) + 2H^(+) (0.1M) + 2Cl^(-) (0.1M)` `DeltaG^(@) = -43600 J` at `25^(@)C` `Delta G^(@) = - n F E^(@)` cell `" "` [n =2] `-43600 = -2 xx 96500 E^(@)` cell `E_("cell")^(@) = (cancel43600^(218))/(cancel2 xx cancel 96500)` `E_("cell")^(@) = 0.225V` `E_("cell")^(@) = E_("cell")^(@) - (0.0591)/(2) "log"([H^(+)]^(2)[Cl^(-)]^(2))/(1) = 0.025 - (0.0591)/(2) "log" 0.1 xx 0.1 xx 0.1 xx 0.1` `= 0.225 - 0.02955 "log" 10^(-4) = 0.225 - 0.02955 xx (-4) = 0.225 + 0.1182` `E_("cell")^(@) = 0.3432V` (b) Fuel cell : A device in which the heat produced as a result of the combustion of fuel (like `H_(2) - O_(2)`) is converted into electricity is called fuel cells. Advantages : (i) Because of the continous supply , fuel cell never become dead . (ii) They do not cause any pollution problem unlike thermal plants which burn fossils fuels like coal , gas oil etc. (iii) They give an efficiency of 60-70% which is superior to thermal plants. |
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