AMMONIA
NH3
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Ammonia is a gas which has a characteristic sharp, penetrating odor. Part of the irritation it causes when smelled is due to its being a base and changing the pH of your mucous membranes.
Pure Ammonia liquifies at -33.5șC. It must be kept in pressure or cryogenic tanks.
The
"ammonia" you commonly see are aqueous solutions. In the laboratory, concentrated ammonia is a 14-15 M solution. Household ammonia generally run about 5% NH3.(can you calculate its molarity?)
In 1996 over 35 billion pounds of ammonia were produced in the United States! It is produced by the Haber Process.

3 H2 + N2 -------> 2 NH3

The reaction is carried out at high temperature and pressure and in the presence of a catalyst
Ammonia is widely used in fertilizers and explosives. Ammonium Nitrate, NH4NO3 is a typical product used for both applications.
It was used in the bombing of the World Trade Center in New York and the Federal Building in Oklahoma City.

In this experiment...
you will prepare ammonia by the reaction of ammonium nitrate with sodium hydroxide.

NH4NO3 + NaOH -----> NaNO3 + H2O + NH3

In testing for ammonia, you will use another important principle:
The solubility of a gas in a liquid generally decreases as the temperature is raised.

(Thats why,  when heating a pan of water,  you see bubbles forming well before the water boils)

In this experiment to test for the absence of ammonia

  • make sure the solution is basic (add NaOH)
  • heat the solution to drive off any NH3
  • test for ammonia with the proper color litmus paper

QUESTIONS
1. Based on last week's experiment, you should be able to answer the following.
A bottle of ammonia has an assay of 29.6% ammonia by weight. If its Specific Gravity is .90, calculate its Molarity.

2. You pour pure liquid ammonia into a beaker(in the HOOD!). Will frost form on the outside of the beaker while the ammonia inside boils?

© RWK