Answer
See the answer below.
Work Step by Step
a) The first reaction is endothermic with $\Delta H_r=206.2\ kJ/mol$, the second is exothermic with $\Delta H_r=-41.2\ kJ/mol$
b)
The number of moles of hydrogen required:
$1.5\times10^{13}\ g\div17.03\ g/mol\times3\ mol\ H_3/2\ mol\ NH_3=1.32\times10^{12}\ mol$
By adding the equations:
$CH_4+2\ H_2O\rightarrow CO_2+4\ H_2$
Mass of CH4 required:
$1.32\times10^{12}\ mol\times 1\ mol\ CH_4/4\ mol\ H_2\times 16.04\ g/mol=5.30\times10^{12}\ g=5.3\ billion\ kg$
Mass of CO2 produced:
$1.32\times10^{12}\ mol\times 1\ mol\ CH_4/4\ mol\ H_2\times 44.01\ g/mol=1.45\times10^{13}\ g=14.5\ billion\ kg$
