1. If there is not sufficient oxygen present a fuel is not completely burned and carcinogenic 'sooty'
and the very toxic gas carbon
may be formed.
2. Fuels like
are very useful but must be carefully stored because they are so
.
3a. As we have seen, there are
problems with using
fuels.
3b. The gas
is in some ways an ideal fuel because it burns very cleanly to form only one product,
!
3c. However, it is a very
gas and would have to be stored under
in cylinders.
4a. There are other chemical
of energy, but they are usually
due to the cost of chemicals.
4b. For example a simple
can be made from two different metals dipped into an
conducting salt solution.
4c. The greater the difference in
, the bigger the
produced.