Hello, my name is Mrs. Collins and I'm gonna be taking you through the learning today.

This lesson forms part of the unit Industrial Chemistry and is called Making ammonia.

During today's lesson, you will learn how to safely produce ammonia in the laboratory.

Here are the keywords for today's lesson: ammonia, alkaline, pungent, toxic, corrosive.

I suggest you pause the video here, read through those descriptions and make any notes if you feel you need to.

Today's lesson will be divided into two parts: Properties of ammonia and Synthesising ammonia.

Let's start with Properties of ammonia.

Ammonia has a simple molecular structure.

Each molecule is made of one nitrogen atom and three hydrogen atoms. At room temperature, it's a colourless gas.

And we can use the displayed formula of ammonia here to show the structure of ammonia, or alternatively, we can use a 3D ball and stick model.

Just to give you an idea, the hydrogen atoms in the ball and stick model are white, and the nitrogen atom is blue.

Ammonia is highly soluble in water and forms ammonium hydroxide.

Here's the formula for that, and we can see it's a reversible reaction and here we are showing the ions that are present dissolved in the water there.

Ammonia is classed as an alkaline gas due to this reaction because aqueous hydroxide ions are produced and these are corrosive.

And ammonia is considered toxic because the hydroxide formed is very corrosive and damages cells in the body on contact.

Unlike some toxic gases, ammonia has a very pungent smell and so is instantly recognisable.

Testing for chemicals using our senses is generally considered unsafe, and chemical indicators should be used to confirm the presence of ammonia.

Safe handling of ammonia gas in large volumes usually involves a fume cupboard, and we can see someone using a fume cupboard there.

Here's a question based on that learning.

Which of the following properties of ammonia gas means it requires careful handling? Pause the video here, answer the question and I'll see you when you're finished.

Welcome back.

Here's the answer to that question.

So it forms a corrosive solution with water and it is toxic.

So we are thinking about factors or properties that means it requires careful handling.

So it is a colourless gas and it has a pungent smell.

Ammonia is very reactive and will react with acids to form salts.

So here we've got a cotton bird soaked in concentrated HCL and a cotton bud soaked in concentrated NH3, and they're being placed into a tube there, which is being clamped.

Inside the tube, we've got a glass rod with damp universal indicator paper on it.

As the hydrogen chloride and ammonia diffuse through the equipment, white powder forms, which is called ammonium chloride, and you can see that underneath in the equation.

So we've got ammonia reacting with hydrogen chloride to form ammonium chloride.

Here is a question based on that learning.

What is or are the products of the reaction between ammonia gas and hydrogen chloride gas? So pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So the answer is ammonium chloride, which is a salt.

We're going to do Task A now.

Ammonia molecules are made from one nitrogen atom and three hydrogen atoms. Draw a dot-and-cross diagram for ammonia.

And two, write a risk assessment for ammonia, including identification of hazards, control measures to limit risk and procedures to follow if a hazard occurs.

Pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So let's go through the answer to that question.

So first of all, there is the structure for ammonia.

We've got the nitrogen in the centre, the three hydrogen atoms. Make sure you draw those electrons in that crossover bit.

A little bit like a Venn diagram there.

So where the circles cross, that's where the shared electrons should appear.

We can see the nitrogen electrons are shown as blue dots and the hydrogen electrons are shown as crosses.

Here's a suggested answer to question two.

Yours might be slightly different, but here's one to have a look at and compare to yours.

So firstly, we need to mention that it's a toxic gas, so we can reduce the risk by either placing it in a fume cupboard or a well ventilated area.

And if there is a problem, you need to move to the fresh air and you definitely need to seek medical advice.

It's strong, it gives it out a strong, irritating odour.

So this means it's best stored in sealed containers and there needs to be proper ventilation.

So if you get any on your skin, you need to wash with water and you need to remove any contaminated clothing.

And then if you get to into contact with your skin or your eyes, to prevent that, wear gloves, lab coats, and eye protection.

And if it happens, wash with plenty of water, remove contaminated clothing, rinse eyes for 15 minutes and seek medical attention.

So well done if your answer looks something like that.

Moving on to part two of the lesson now, Synthesising ammonia.

So ammonia can be synthesised in the laboratory by heating a mixture of ammonium salt and an alkali.

This will produce ammonia gas as well as other byproducts.

So we've got an example here where we've got ammonium chloride reacting with calcium hydroxide, forming calcium chloride, water, and ammonia.

As ammonia is very soluble in water, we can add other chemicals as desiccants to the reaction to stop this from happening.

So desiccant stops the ammonia dissolving in any water that's present.

So here's the reaction so we've got calcium oxide plus water forming calcium hydroxide.

So here's a question based on that learning.

Ammonia reacts with alkaline solution to form ammonium salts.

Is that true or false? Justify your answer using the statements below.

Pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So let's go through the answer.

It is, in fact, false, and that's because ammonium salts react with alkaline solutions to produce ammonia.

So well done if you got that correct.

So here's a follow up question: Which of the following combinations can be used to synthesise ammonia gas in the lab? So pause the video here, read through those statements, decide which one's correct, and I'll see you when you're ready.

Welcome back.

So let's go through the answers to that question.

So ammonium chloride and sodium hydroxide is a possible route as is ammonium nitrate and calcium hydroxide.

So well done if you got that correct.

We're now moving on to Task B, and this time we're having a go at synthesising ammonia.

So you may see this as a demonstration.

You may get an opportunity to do this as a practical yourself, but here's the method.

So we are going to mix spatulas of ammonium chloride with calcium hydroxide in a beaker, and the two solids will react immediately.

We're gonna hold a damp piece of each colour of litmus paper, as well as a piece of damp universal indicator paper over the mixture and observe the colour change.

We're gonna transfer the mixture to the setup on the next slides, and gently warm the mixture, collecting ammonia in a dry boiling tube and observe what happens, recording and explaining the observations.

So here is the setup for heating the ammonium hydroxide and calcium hydroxide there, collecting the ammonia gas in a dry boiling tube.

Remember, ammonia will dissolve in water, so we need to make sure it's a dry boiling tube.

There's no moisture inside there.

And then after you've collected ammonia gas in a dry boiling tube, submerge it in a beaker of water like shown, and remember to test the water before and after with the universal indicator paper.

So your writeup, your observations may look something like this: So we've got the results for the litmus paper and the universal indicator paper.

So the colour change, red litmus paper will change to blue, blue litmus paper will stay the same, and universal indicator paper will go potentially from yellow to blue or purple.

These all show that an alkali was present.

When ammonia dissolves in water, it produces hydroxide ions as well as ammonium ions.

When the boiling tube was submerged in the beaker of water, the level of the water rose.

This is because the ammonia dissolves in water, so the water dis displaces the gas as it dissolves, shown by the universal indicator turning blue.

So that's proof that the ammonia has dissolved in the water.

So well done if your answers look something like that.

Here is a summary of today's lesson: So ammonia can be synthesised in the lab by heating a mixture of ammonium chloride and alkali, producing ammonia gas and other byproducts.

Ammonia is an alkaline gas that reacts readily with water to form a basic solution, turning moist red litmus paper blue, indicating its alkaline nature.

And ammonia reacts with hydrogen chloride gas from concentrated hydrochloric acid to form a white solid salt, ammonium chloride.

So thank you very much for joining me for today's lesson.