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.
In this tutorial, we will learn followings.
Before learn experiments, we should learn about characteristics of ammonia gas. It will help to understand the experiments very well.
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.
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.
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.
The ammonia solution will show you higher pH value than 7 while sulfur dioxide solution will have a less pH value than 7.
With come cations such as Al3+, Zn2+, Cu2+ aqueous ammonia solution can give precipitates.
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.
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.
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.
Both gases are colourless. So we cannot identify them by observing colours of gases. Carbon dioxide is an acidic gas.
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 is an inorganic compound which is a gas at room temperature.
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.