N 82._ A woman scorched the oatmeal she was cooking
for breakfast. When she wanted to wash the pan, she found that
the blackened cereal stuck fast to the bottom. Which of the
following things would have served best to loosen the burned
oatmeal from the pan: lye and hot water, ammonia, vinegar,
salt water, lemon juice?

INFERENCE EXERCISE

Explain the following:

521. After clothes have been washed with washing soda or
strong soap, they should be thoroughly rinsed. Otherwise they
will be badly eaten as they dry.

522. Carbon will burn; oxygen will support combustion; yet
carbon dioxid (CO_2), which is made of both these elements,
will neither burn nor support combustion.

523. You can clean silver by putting it in hot soda solution
in contact with aluminum.

524. When you stub your toe while walking, you tend to fall
forward.

525. Electric lamps glow when you turn on the switch.

526. If you use much ammonia in washing clothes or cleaning,
your hands become harsh and dry.

527. If a person swallows lye or caustic soda, he should
immediately drink as much vegetable oil or animal oil as
possible.

528. Water is made of hydrogen and oxygen; air is made of
nitrogen and oxygen; yet while things will not burn in water,
they will burn easily in air.

529. The backs of books that have been kept in cases for
several years are not as bright colored as the side covers.

530. If you try to burn a book or magazine in a grate, only
the outer pages and edges burn.

SECTION 56. _Neutralization._

When you put soda in vinegar, what makes the vinegar less
sour?

When we use sour milk for cooking, why does the food not taste
sour?

One of the most interesting and important facts about acids and bases
is that if they are put together in the right proportions they turn
to salt and water. Strong hydrochloric acid (HCl), for instance, will
attack the skin and clothes, as you know; if you should drink it, it
would kill you. Caustic soda (NaOH), a kind of lye, is such a strong
alkali that it would dissolve the skin of your mouth in the way
that lye dissolved hair in Experiment 108. Yet if you put these two
strongly poisonous chemicals together, they promptly turn to ordinary
table salt (NaCl) and water (H_2O). Or, as the chemists write it:

NaOH+HCl -> NaCl+H_2O.

You can make this