Coal can be used to generate hydrogen gas (a potential fuel) by the endothermic
ID: 1026899 • Letter: C
Question
Coal can be used to generate hydrogen gas (a potential fuel) by the endothermic reaction: C(s) + H20(g) CO(g) + H2(g) If the re formatio the quantity of hydrogen gas. action mixture is at equilibrium, predict whether each disturbance will result in the n of additional hydrogen gas, the formation of less hydrogen gas, or have no effect on a) adding more C to the reaction mixture. b) adding more H20 to the reaction mixture. c) raising the temperature of the reaction mixture. d) increasing the volume of the reaction mixture. e) adding a catalyst to the reaction mixture. ) adding an inert gas to the reaction mixture. NO.efcot 3Explanation / Answer
the reaction is C(s)+H2O(g) ------>CO(g)+H2(g)
enthalpy change= 1* standard enthalpy change of CO+1*standard enthalpy change of H2-{1* standard enthalpy change of H2O+1*standard enthalpy change of C(s)}
standard enthalpy data (Kj/mole): C=0, H2O= -241.8, CO= -110.54 and H2= 0
standard enthalpy change = 1*(-110.54)-{1*0+1*(-241.8)} =131.3 Kj, since deltaH is +ve, the reaction is endothermic
K= Equilibrium constant = [CO][H2]/[H2O]
since K is independent of mass or concentration of Carbon, addition of C does not affect the equilibrium. so there is no addition of H2gas.
2. when more moles of H2O are added, [H2O] increase and Q= reaction coefficient = [CO][H2]/[H2O] <K since [H2O] is increased. So more of CO and H2 have to form to ensure Q=K. So the reaction shifts towards products. so hydrogen production is favored.
3. since the reaction is endothermic, as the temperature is increased, the reaction shifts so as to nullify the effect of temperature. so exothermic direction is preferred and hence the reaction proceeds towards the reactants side. So there will be decrease in production of H2.
4. as the volume of reaction mixture is increased, the reaction shifts in a direction of decreasing volume. Since from gas law PV =nRT and Volume is proportional to no of moles, the reaction shifts in a direction where there is a decrease in no of moles, so backward reaction is favored.
5. The catalyst is foreign substance which allows reaction to proceeds in an alternative path and since it does not participate in the reaction, it does not affect the equilibrium constant
6. The addition of an iinert gas for a system which is at equilibrium at constant volume, the total pressure will increase. But the concentrations of the products and reactants will not change.
Addition of an inert gas is to a system in equilibrium at constant pressure, leads to increase in total volume, Hence, the number of moles per unit volume of various reactants and products will decrease. Hence, the equilibrium will shift towards the direction in which there is increase in number of moles of gases. Hence more H2 is produced.