* Star Question * What are your favourite experiments? – Ruth, Live Chat

Will Breeze answered on 18 Jun 2020: last edited 18 Jun 2020 10:53 am

It’s hard to choose! Definite contenders for the top spot for me would be:

1. Flame test: Dipping a wire in a salt solution, then putting it in a Bunsen burner flame to watch the colour change depending on the type of salt. (looks very cool).

2.Chromium Redox reaction: Using Chromium (VI) as an oxidising agent. Looks very impressive as it turns from Chromium(VI), which is vivid orange, to bright green Chromium (III) instantly. (Don’t try this at home kids, Chromium (VI) is incredibly toxic!)

3. RAFT polymerisation: Not impressive to look at, but it allows you to make polymers with a very narrow chain length distribution which is incredibly useful for industry. The mechanism for this looks impressive on paper if curly arrows are your kind of thing.

4. Polymerising ethylene using the brand-new catalyst I made. This one is very personal, as it was the topic of my university thesis. It didn’t work, but that’s OK, because that taught us about what the limits of the chemistry involved were. Sometimes a ‘bad’ result can be as important in learning new things!

Heather Walton answered on 18 Jun 2020:

I think my favourites are all the ones which involve colour changes because they’re so fun to watch! At school I did a project making dyes and watching water change into a coloured solution as they were made is still what I think of as a cool chemistry experiment. But experiments which don’t necessarily look particularly fun can be really really satisfying if they give you an important result to either back up or change your conclusion as well.
Generally I’m more of a fan of experiments where you get to do everything yourself, rather than a machine doing it, but I think that’s just because I’m a person who doesn’t like to sit still!

Suwanie Thakrar answered on 18 Jun 2020:

The ones I can do at home! like using turmeric as an indicator. Take some tumeric powder, mix it with water. That’s your indicator.

Now prepare your acid and basic samples. For your acid, take some lemon juice. For your base, mix some dish soap with water.

Add 3 drop of the indicator to about 10 ml of lemon juice. No add 3 drops of the indicator to around 10 ml of soap water. What colour changes do you see?

Tanya Batchellier answered on 18 Jun 2020:

Nothing beats an experiment that you’ve designed and done yourself (even if it does go wrong)!

The most memorable experiments I’ve seen have often been done by other people. My favourite experiments were always the ones teachers would do towards the end of term which were a bit of fun!
My two favourites were:
– Screaming Jelly Babies (molten potassium chlorate reacting with the glucose in a jelly baby to make a high pitched scream)
– Elephant’s Toothpaste (hydrogen peroxide and yeast or potassium iodide)

Another one would be making ice cream using liquid nitrogen!

Andy Kowalski answered on 18 Jun 2020: last edited 22 Jun 2020 12:33 pm

Basically using TLC on different items and seeing separation of components happening, inks were a good example!

Analysis of fruit juices for acid content.

Analysis of Bleach for Chlorine content.

Synthesis of nitrobenzene.

Differentiation of aldehydes and ketones, use of Silver mirror test.

Lasaigne test of unknown organic mixtures.

Rachael Hallam answered on 18 Jun 2020:

Any experiment with a colour change indication is always nice to do! I prefer shorter, simpler ones, as sometimes you can have a long experiement with many steps, and if it doesn’t work it can be difficult to isolate which step failed.

Megan Greaves answered on 18 Jun 2020:

As most people have said – things with a colour change. I make complexes containing nickel, they are often brightly coloured because it’s a transition metal. I have had powders of all colours of the rainbow; purple, organge, green, yellow, blue, pink! It also makes it really easy for me to see if my reactions have worked. If I end up with something brown or black at the end, it normally means my reactions have failed – this happens often, although it all pays off once I finally make my coloured complexes!

Ronan Bellabarba answered on 18 Jun 2020:

A demonstration of catalysis
Take a sugar cube and try to light it with a flame. It won’t burn it will just caramelise.
Take some ash (fresh might be best) and dip the now tacky cube into it. Light again: the cube should burn with a flame.
The alkali metals in the ash accelerate the combustion.

Tiffany Chan answered on 18 Jun 2020: last edited 18 Jun 2020 3:59 pm

Tricky question! As others have said, colour change experiments or experiments that make shiny crystals are always nice.
In terms of experiments that you can do at home, my favourite is probably extracting DNA from strawberries (https://www.genome.gov/Pages/Education/Modules/StrawberryExtractionInstructions.pdf) 🙂

Julie Watts answered on 18 Jun 2020:

Well, colour changes are always good!
One of my favourite experiments was looking at silver nano-sized particles inside a transmission electron microscope. As you probably know in solid metals the atoms are in rows and these are stacked on top of each other. The microscope I use is not powerful enough to ‘see’ one atom on it’s own, but we can look at a stack of atoms. What I did then was to heat the silver really quickly to a very high temperature and watched the dots which were columns of atoms. I expected the silver to melt, but surprisingly I saw the metal get smaller and smaller and finally disappear completely. I realised I had just watched the process of sublimation and the solid metal had turned into a gas. Because the microscope operates in a vacuum, the gas was simply pumped away and ‘disappeared’.

Pamela MacDuff answered on 19 Jun 2020:

Screaming jelly baby is always a fun one. You put a jelly baby in molten potassium chlorate and get a jelly baby “screaming” and this ultra bright purple/pink light given off.
I love working with transition metals though because the complexes they make are usually really colourful – think about the lovely blues of copper sulphate and copper chloride.

anon answered on 19 Jun 2020:

As the others have said, difficult to choose! But if I have to, I choose recording human cells dividing with a microscope. With special microscopes we can record cells growing in a plastic/glass dish and see how the change along time, how they move, how they transport material inside themselves, how they communicate between each other and my favourite, how they divide. This process of cell division is called MITOSIS. For this process, each cell from animals and vegetables duplicates all of its contents, including its DNA, condenses the DNA into structures called chromosomes, divides itself into 2 daughter cells and equally distributes the chromosomes between them. This way, each daughter cell is exactly identical to the original cell. Inside each human, this process happens around 10,000,000,000,000,000 times along his/her lifetime!
You can see some examples here https://www.youtube.com/watch?v=L61Gp_d7evo.

Fred Mosselmans answered on 22 Jun 2020:

Well my favourites experiments recently I guess are investigations into metal on metal hip implants failures, understanding why the metals in the alloys cause biological reactions in some patients tissues and looking at how to stop degradation in the artefacts from the Tudor warship Mary Rose, by looking at the chemistry of the sulfur , iron and other elements to understand how to stabilise them

Aisling Ryan answered on 23 Jun 2020:

My favourite experiments are colourful ones!! I am a chemist and my job is to mix chemicals together to make new medicines to treat cancer. Some of the medicines I make are bright red, or orange, and a lot of them form very pretty crystals. These ‘aesthetically pleasing’, or pretty experiments are always my favourite! 🙂

Katherine Haxton answered on 24 Jun 2020:

I like the Belousov Zhabotinsky oscillating reaction – it changes colour between red, blue, purple and green because of really complex chemical reactions taking place but it seems like magic.

Jane Patrick answered on 24 Jun 2020:

I do a reaction at work in which starts with a bright pink solution of cobalt sulfate. I then add an equal volume of something called an organic extractant (which is a colorless liquid). The organic liquid floats on top of the copper sulfate solution – like oil floating on top of water. When I mix the two solutions together, the pink solution (the bottom layer) becomes colorless and the the colorless solution (the top layer) turns dark blue.

This happens because the cobalt metal in the bottom layer has moved into the
top layer. It changes color because it has moved from a water solution to an organic solution.

This is called a Solvent Extraction experiment. I’ve seen it hundreds of times but still love it!

Kat Hunter answered on 25 Jun 2020:

Anything with fire?! If you’re asking just in general – I love elephants toothpaste and the reaction between the alkali metals (sodium, potassium etc) with water – its so cool to watch them fizzing about on the water surface! If you mean in work – I get to do a load of different ones it’s too hard to choose! Some of my favourites are making free standing electrodes – this involves mixing the material of interest with a polymer and conductive agent and forming a putty – then rolling it out and cutting out disks to examine/test. Another one is where I mix a precursor biomass material with a hydroxide and put it in the oven – then a cake basically comes out! Both experiments are really similar to baking!

Alex Ttofi answered on 26 Jun 2020:

Like the answer Heather gave below colour change is good for children. My favourite (and one I have used many times) is an Iodine solution with starch. It goes from clear to black when mixed. Line up lots of beakers with Starch then lower the Iodine concentration as you go along before adding them together. The more concentrated will change colour immediately then it becomes a guessing game when they change. If you get it right they will gradually and suddenly change colour as you talk to a group of children. Can be very good fun and good fun for them watching and guessing when

Zoe Ingold answered on 26 Jun 2020:

I work with proteins and my favourite routine experiment to do is protein purification because it’s so rewarding when it works! I also love crystallography because it allows me to work out the structure of my proteins and this can tell me a huge amount about how it works.

Chris Holdsworth answered on 29 Jun 2020:

Measuring isotopes of carbon and oxygen and using them as an indicator for past temperature records. I think it’s incredible that we can get so much information about past environments and climates from looking as such tiny differences in chemistry!

Question: * Star Question * What are your favourite experiments? - Ruth, Live Chat

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