NAME__________________________________________________________
1) A gallon of gasoline can be thought of as 2660 grams of octane.
a) Find the number of kJ obtained by burning 1 gallon of gasoline
b) Assume a car gets 22 miles per gallon. Find how many kJ is used per mile
c) Recall that only 25% of the cars burned energy is changed into actual
motion
How many kJ from a gallon are converted into motion
2) You are going on a backpacking trip in which you must carry food
and supplies(including fuel) for 1 week. Your fuel can be any of the first
10 alkanes
a) What type of alkane data(kJ/mole or J/g) will be most useful in making
a selection? Why? ____________________________________________________
b) Which alkane would you use as fuel (see book charts) Why__________________
_______________________________________________________________
c) In reality what other factors must you consider if you chose one of the
gaseous fuels as your
choice__________________________________________________
3) The average person burns 12,000 kJ of food energy per day
(we normally express this as 2800 Calories per day)
The heat of combustion of sugar is 4Cal / gram
The heat of combustion of fat is 9Cal / gram
a) How much (grams of) sugar must you eat to get a days supply of energy
b) How much (grams of) fat must you eat to get a days supply of energy
c) If your body ran on gasoline,how much (grams of) gasoline must you drink
to get a days supply of energy ? How much is this in gallons?(see#1)
4) Cars can burn grain alcohol instead of gasoline. A car which drives
15,000 miles per year and gets 20 miles per gallon needs the alcohol made
from 16,500 pounds of grain.
The average person can survive if given 400 lbs of grain per year (imagine
eating 355 medium sized boxes of Wheaties)
An average acre of land produces 1890 lbs of grain per year
a) How many acres of grain must be grown to supply the average car with
alcohol
b) How many people could these acres(answer to "a") feed
c) How far can a car go on 1 lb of grain( a box of Wheaties) that has been
changed to alcohol
d) There are 135, 000, 000 cars in the US today. How many acres of grain
are needed to produce alcohol for these cars (use answer to "a")
e) There are 29,000,000 acres of farm land in Illinois. Could Illinois produce
enough grain to power all US cars