Hydrogen

Expressing enthalpy?

the most common method for the production of hydrogen gas is through the reaction of steam with hydrocarbons such as methane gas. the equation for the reaction involved is as follows
CH4(g) + H2O(g) —> CO(g) + 3 H2(g)

CH4(g) + H2O(g) —> CO(g) + 3 H2(g)

Because of the sequence of the explanation I will begin to answer with (b).
b) The equation shows that when 1 mole of methane (CH4) reacts with H2O, 1 mole of CO and 3 moles of H2 are formed. Since the given energy value belongs to 1 mole of CH4, this means that the enthalpy (heat) of this reaction is 206.1 kJ. Since this amount of heat is absorbed by the reacting system, the reaction is endothermic. The thermochemical equation for this reaction will be;

CH4(g) + H2O(g) —> CO(g) + 3 H2(g) …. ∆Hr = + 206.1 kJ

If a reaction is exothermic, the reverse of it is endothermic, or vice versa. Therefore, the reverse reaction will be exothermic;

CO(g) + 3 H2(g) —> CH4(g) + H2O(g) …. ∆Hr = – 206.1 kJ

a) Now we can solve (a).
206.1 kJ of heat is absorbed during the reaction of 1 mole of methane which is 16 grams ( molar mass of methane).
When 16 g methane reacts, 206.1 kJ of heat is absorbed,
When 1.00 kg = 1000 g CH4 reacts, the heat to be absorbed will be;
206.1 kJ x (1000g / 16 g) = 12881.25 kJ

c) The x – axis will be “reaction coordinate” or “reaction path way”. The y – axis will be “potential energy”. Since the main reaction is endothermic, this means that, the sum of the potential energies of reactants is less than that of products. Therefore we supply energy (or system absorbes energy) to reach the levels of the products. Therefore, draw two lines parallel to x -axis.The lower one will belong to CH4(g) + H2O(g) and the upper one will belong to CO(g) + 3 H2(g). Join the end point of the lower line to the starting point of the upper line.
Something like that;
………………______
……………./
…………../
_______ /

Make your own Hydrogen : Part 1