7. What is the molecular weight of ethyl alcohol (ethanol), CHOH? In an equimolar mixture of ethanol and water, what is the percent ethanol by weight?

8. In the old definition, 100-proof alcohol was the weakest alcohol-water mixture that could be set afire by a match after being poured over gunpowder. In a more recent definition, 100-proof spirit is 49.28% ethanol by weight. What is the ratio of relative numbers of moles of ethanol and water in 100-proof gin? (Ignore minor components.)

9. The Hindenberg and the Graf Zeppelin II, Germany's last two great lighter-than-air craft, originally were designed to use helium for lift rather than hydrogen, and only the American embargo on export of helium from the Texas oil fields forced the Hindenberg to use hydrogen. The result was the tragic crash and fire in New Jersey in 1936, which marked the effective end of commercial dirigible travel. The total volume of the Hindenberg's gas bags was 200,000 cubic meters. At 250C and 1 atm. pressure, how many moles of hydrogen gas would be required to fill them? How much would this hydrogen weigh?

10. How much would an equivalent volume of air weigh (see Problem 9)? How much weight could the Hindenberg lift (including the weight of the airship itself) ?