Testing Ammonia Gas in Laboratory | Identify Ammonia

Ammonia is an inorganic compound which has hazardous characteristics and very important gas in chemistry. Here we are going to discuss, how we identify or testing ammonia gas in the laboratory by different experiments. Doing experiments with ammonia and such other toxic gases, you should be very careful about safety of you and people around you.



ammonia molecule

In this tutorial, we will learn followings.

  • Characteristics of ammonia gas
  • Experiments for testing ammonia gas
  • Example problems and questions, how to identify ammonia from other gases


Before learn experiments, we should learn about characteristics of ammonia gas. It will help to understand the experiments very well.


Characteristics of ammonia gas

  • Colourless - You cannot see a colour such as brown colour of NO2
  • Toxic - Don't try to inhale feel the gas. Inhaling ammonia to your body may cause death.
  • Basic - give a alkaline aqueous solution in the water.
  • Has an unpleasant smell

Identify ammonia gas - experiments

Following experiments can be done to identify ammonia gas in the laboratory. But, some experiments cannot done. They are noted specially because those experiments can cause injuries to you. Those are helpful to identify when you feel like a leakage of ammonia gas.


  1. Add nessler reagent, then it will turn into brown colour.
  2. When get close to the concentrated HCl bottle lid, ammonium chloride (NH4Cl ) white solid fog will be made.
    ammonia and hydrochloric acid react to give solid white ammonium chliride smog

  3. Ammonia has an unpleasant smell and is a basic gas (form an alkaline solution in the water).
  4. Ammonia will turn red litmus to blue litmus.
  5. NH3 dissolve very well in water. Then check the pH of solution. You can see pH is greater than 7. It says aqueous ammonium solution is a basic one.
    Aqueous ammonia solution

  6. A colourless gas.


Identify ammonia gas from other gases

In next section, we are going to discuss how to identify ammonia gas from other different gases. These gases may contain similar properties to ammonia.

Ammonia is identified from following gases in this section.

  • Sulfur dioxide - SO2
  • Hydrogen sulfide - H2S
  • Nitrogen dioxide - NO2
  • Carbon dioxide - CO2


Testing ammonia gas from pH value

Send ammonia gas to a dilute water and measure the pH. What will you see? Obviously, you see the pH value is greater than 7.


How to identify ammonia from sulfur dioxide by a pH test?

Ammonia and sulfur dioxide are colourless gases cannot identify by colour differences. Therefore send both gases separately to two distilled water samples. And check the pH of the solutions.

The ammonia solution will show you higher pH value than 7 while sulfur dioxide solution will have a less pH value than 7.



Aqueous ammonia solution can give precipitates

With come cations such as Al3+, Zn2+, Cu2+ aqueous ammonia solution can give precipitates.


Propose a test for ammonia gas to identify from hydrogen sulfide

We use the forming precipitate with ammonia aqueous solution to identify hydrogen sulfide.

Send ammonia and hydrogen sulfide gases to two Al3+ aqueous solutions. Observe what will happen in two solutions.

In one Al3+ solution, a white precipitate is given due to ammonia. Ammonia produces hydroxyl ions in the water and as the white precipitate, Al(OH)3 is given.



Testing ammonia gas and nitrogen dioxide gas

So easy to do this. Actually like nothing to do. Just observe colours of gases. Nitrogen dioxide is a brown gas and can be identified clearly from ammonia.



Testing for chlorine gas and ammonia gas

Take an concentrated HCl bottle and open its lid. Be careful! HCl vapour comes out from the bottle immediately and remember to wear safety equipments to prevent injuries.

Send two gases close to the concentrated HCl bottle. in separate occasions, and observe the changes.

Related to ammonia gas, a white solid fog, ammonium chloride is given. No that kind of change is for chlorine gas.



Identify carbon dioxide from ammonia

Both gases are colourless. So we cannot identify them by observing colours of gases. Carbon dioxide is an acidic gas.

  1. Send carbon dioxide to calcium ion solution. It gives, a precipitate with milky colour.
  2. Send ammonia gas to calcium ion solution, you cannot see a precipitate like given by carbon dioxide gas.


Ammonia will turn red litmus to blue litmus

Red litmus papers turns blue in the presence of ammonia gas or aqueous ammonia solution. This will prove ammonia has basic characteristics.

But, do not forget ammonia has acidic characteristics too.





Ammonia releasing reactions



Questions


ammonia organic or inorganic?

Ammonia is an inorganic compound which is a gas at room temperature.


Where ammonia gas testing experiments are applied?

To prove, exist of nitrogen gas in the atmosphere. Heat a magnesium metal piece in the air. Then add it to the water and do ammonia gas testing. You will observe there are characteristics of ammonia from those experiments.


Related tutorials

Ammonia and ammonium salt reactions Oxides of nitrogen Nitric acid manufacturing



Lewis structures

P2O5 lewis structure OH- lewis structure Ammonium ion (NH4+) lewis structure H2CO3 lewis structure
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