Hydrogen

We are currently having a space themed week in school to celebrate the 50th anniversary of the moon landings. not quite the 50th anniversary, more like 49 and 49/50ths (Armstrong walked on the lunar surface on the 16th July 1969) but as we break up on Friday it was the best the school could do. The students have a few days off timetable and are engaged in many different activities that relate to the moon landings.

In chemistry, I guess we have things easy. We are putting on a number of lab sessions for students to investigate hydrogen – with the link being that this is a potential fuel that could be used in space rockets in the future.

Our lab sessions have involved a few demos and a class experiment. I’ll tell you what we have carried out below but it goes without saying that if you try to reproduce any of the labs or demos that you, the teacher, are solely responsible for carrying out the appropriate risk assessments and that you check that you can safely carry out these labs and demos.

We start off using the whoosh bottle. You need a large drinking fountain bottle and some alcohol – we use propan-2-ol. Approx. 40cm3 is put into the bottle, it is swirled around to increase its surface area to allow it to evaporate and the remaining alcohol (usually around 20cm3) are poured back out of the bottle. A bung is placed over the top. The class moved to a safe distance and then the fumes are set alight from a safe distance (usually using a splint attached to a 1m ruler). The results are dramatic as you can see in the clip below. OK, nothing to do with hydrogen but it gets the idea over to the students!

Our class lab involves getting the students to make hydrogen by reacting sulphuric acid with zinc granules and collecting the hydrogen by upwards displacement of water. The test tubes used to collect the hydrogen in have marks on the side and the students collect hydrogen up to the mark. The test tube is then carefully pulled out of the water, keeping it upturned to allow air inside and a bung inserted. Essentially, the students collect four test tubes of differing hydrogen to air ratios.

The hydrogen is ignited. It is noticeable how the sound made changes as the ratio of air to hydrogen changes. This gets the students thinking of molar ratios and also the correct proportions of hydrogen and oxygen (or air) needed to produce the greatest amount of energy.

I hope you have found this blog post useful and that it has given you a few ideas – here is one more – could this possibly be a theme for a group 4 project? 

Do you have any interesting investigations you carry out with hydrogen – if you do, please let me know, I’d love to hear about them.

 

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