Hydrogen gas is a very useful reagent with many uses in the
petroleum, food, and chemical industries. Most hydrogen exists in
covalently bonded molecules, and atmospheric air contains less than
1 ppm of diatomic hydrogen. Therefore, hydrogen gas is produced on
a large scale for these uses, where steam reforming with methane
and electrolysis of water are two of the primary methods. The more
economic reaction of steam reforming is the reverse of the reaction
depicted in Carbon Monoxide and Hydrogen – Sample 1 in the
Simulation. Hydrogen has also been considered as an alternative
fuel for vehicles designed to combust hydrogen and oxygen, which
produces water as a product. However, concerns were raised because
methane is typically used on a large scale to produce hydrogen gas.
Assume that a gallon of gasoline contains 2400 g of carbon. If a
gasoline engine achieves 30 miles per gallon, each mile consumes 80
g of carbon (about 107 g of methane contains 80 g of carbon).
Alternatively, a hydrogen engine can achieve 80 miles per kilogram
of hydrogen gas. What is the mass of methane (CH4) needed to
produce enough hydrogen gas (H2) to drive one mile using the
theoretical hydrogen engine? Express the mass in grams to two
significant digits.