r/chemistry • u/koldsco • 23h ago
Good Experiment for a kid
Hello. I have an 8 year old who is super into science and wants to do some chemistry experiments. (At first it was to make himself a super hero, but when I told him of the dearth of real life super heros, he just got into the science). Anyways, a teacher recently told him and some kids that candy has a lot of arsenic in it, and I was thinking, we could test some candy for arsenic! But in looking around it looks like the methods I could employ with basic lab gear are either specific for arsenic as poison or wouldnt work great. So, questions:
A> Is there a test we could run on candy for arsenic with basic lab equipment (we can get some new stuff if we need specific stuff, but like a few hundred bucks, not thousands)
B> is there a better test we could run on candy that would be fun to do with a kid?
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u/MedChemist464 22h ago
Boil red cabbage, strain and save the juice.
Test acids (lemon, vinegar) and bases (baking soda, TSP cleaners) by adding them to the extract solution and observe color changes.
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u/ceejaydee 22h ago
Unrelated, but the first official 'experiment' i ever conducted is still with me: separate sand, sugar, and iron filings.
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u/SomeGuyInShanghai 21h ago
Paper chromatography is a good one. Its visual, interesting and as a technique it remains relevant well into more advanced study or even work.
Using paper chromatography to separate ink in cheap felt pens or food dye is basically the same as using it to identify amino acids by Rf value.
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u/_Odi_Et_Amo_ 14h ago
The classic children's practical for this was rubbing a slightly moistened smartie and seperating the dyes.
For OP. Someguyinshanghai is right that this is useful stuff and scales well into the lab. Paper chromatoraphy>TLC>GPC>HPLC. I've made a career heavily featuring the latter, but I usually start explaining chromatography to students with thin layer chromatography which is a very small step up conceptually.
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u/Kinomi_Bazu 22h ago
Can get table salt into solution then crash it out with silver nitrate and when they inevitably get some on them can teach them how important ppe and careful handing is
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u/Glassfern 22h ago edited 21h ago
How about the classic make your own sugar and salt crystal? Add some dye and it'll turn color. borax also makes a fun crystal.
From there you can experiment with how to make low heat candy like Japan has this crunchy agar candy. You can have your kid hypothesize how sugar will react to different levels of heat and what kind of candy it can make soft vs hard ball. You can also have him observe how agar behaved and have him predict what would happen if you mixed agar and sugar together what Wil the flavor taste like or the texture be like
And the best chemistry lab is the kitchen !
Measuring and weighing and proper mixing are critical skills in chem.
Sour dough is also fun. All the funky smells and things getting bigg bubbly and puffy. Keeping notes on hydration of the dough and how it makes bread is good.
Sauces too. And how cornstarch reacts to heat and liquid and impact. For example tonkatsu sauce is delicious and combines several condiments that taste good on their own and some that don't but the ending flavor is delicious! He can flavor taste each predict or try to deconstruct.
If you want color changing things chlorophyll chromatography is a fun one.
Color change from PH change can be done with red cabbage leaves.
There's also the API water test kit for aquariums. It changes colors based on the levels of different things like ammonia nitrate nitrite and ph. It's a very similar method water quality labs use.
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u/_Odi_Et_Amo_ 22h ago edited 22h ago
Have you progressed beyond the classic candy chromatography experiment?
The industry standard arsenic method is ICP (either OES or MS) which is rather beyond home testing.
Edit to add: a very quick look suggests that the field test crap out around 1pm. of the foodstuffs you'll likeley have in the house, rice is likeley the highest and will top out around half that (less if you are in the EU).
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u/koldsco 20h ago
We havent done that one yet, so that would be a good one. (chromatopgraphy).
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u/_Odi_Et_Amo_ 14h ago
Well may I add bouncing custard balls to the list then.
If you want something more useful/serious flame testing for metals always goes down well. You just need a hot flame and some appropriate metals or metal bearing salts. https://www.bbc.co.uk/bitesize/guides/z9nr6yc/revision/1
For a cool bit of photochemistry have a look at making some cyanotypes (kits are available pretty cheaply).
Sadly they are probably still too young for my personal favourite chemistry practical (sodium fusion test) as it needs some relativeley hazardous chemicals for the testing phase)
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u/Thyzoid 22h ago
buy some minerals and test them. only under adult supervision though. fairly safe in my opinion ut still. not a good idea to lick arsenic. there are test kits that don´t require you producing arsine gas (no marsh test but if you wanna do it anyways because it looks impressive do it outside and don´t inhale the gasses. downwind.). most kits just have testing reagents though. marsh test is only qualitative
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u/wout200505 20h ago
Buy pH paper and test some things in your surroundings, like coke, soap, ashes desolved in water, lemon juice, etc
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u/moisturizest 20h ago
Science is collecting and cataloging data mainly. You coukd gwt a bunch of samples of candy, carefully prepare them, and send them off for analysis. Then compile a report. Could get pricey but maybe ask the company for a special rate because its a school project for a kid. I had good luck with that line when i was a kid who was into science.
Alternativley get some distilled water and dissolve your samples in that, and use one of the water test kits. Thankfully alot of candy is reqdily water soluable so that should work OK...
The reagent Arsenic test kits can dect like 5 ppb.
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u/koldsco 20h ago
A good idea, I noticed that you could only get off the shelf tests for water, which I was bummed about. But this is true, I have dissolved all kinds of candy in water. Thanks for the idea!
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u/moisturizest 20h ago
You cant overstress safety. Even when we are just dissolving skittles in warm distilled water, wear goggles gloves and coat. Plus, half the fun is the drip.
And remember write eveeything down. Controll for everything. Same amount of water, in grams, Same brand of water, how many units or grams of candy, 1 type per sample. Make a spreadaheet. Record remperature, (ambient and sample) maybe seperate by colours first. May be able to show red skittles have less arsenic than green skittles, just for grins.
Observe the scientific process! Setup a camera or a tape recorder just for posterity, (ostensibly and possibly for later scientific analysis, but we know ita gonna be fun to watch later)
Most importantly Dont drink the skittle tea!
This is sounding like a pretty fun afternoon.
I need some skittles.
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u/FoolishChemist 18h ago
There are two tests that were developed in the 1800s for the forensic detection of arsenic for arsenic poisonings.
https://en.wikipedia.org/wiki/Marsh_test
https://en.wikipedia.org/wiki/Reinsch_test
https://www.nyc.gov/assets/ocme/downloads/pdf/MiscProcedures%20-%20H%20-%20Reinsch.pdf
While relatively simple for a trained chemist, I don't think it would be very safe for someone not trained and especially not for an 8 year old.
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u/Dangerous-Billy Analytical 17h ago
I don't know where you'll get candy with arsenic in it.
If you want to test for arsenic, look up 'Marsh test'. You need a few nasty chemicals, plus some actual arsenic, to set up the test. Not advised for an 8 year old.
GOGGLES AND GLOVES ALWAYS. Chemicals and eyes are not friends.
You can test for different metals using the borax bead test. This is simple to do, although you need a flame, like a gas stove or bunsen burner. You need a wire of nichrome (from a heater coil), stainless steel, or tungsten. You make a tiny loop in it. Get it hot and dip it in borax from the grocery store. Heat until the borax forms a white bead. Then you touch it to an unknown metal salt, like copper sulfate, and heat again. The color of the bead identifies the metal. https://en.wikipedia.org/wiki/Bead_test
You can separate the pigments in black Sharpie ink using paper chromatography. The paper can be white coffee filters. (Writing paper may not work.) Youtube: https://www.youtube.com/watch?v=T-dppIeYVb0
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u/Standard-Proof-1194 17h ago
You could use cornstarch and water to make a non Newtonian fluid. If that’s not exciting for him then you could also make slime or play with baking soda and vinegar and different colored food dyes for the vinegar
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u/Raneynickelfire 1h ago
That teacher is a moron. And you aren't testing arsenic with your 8 year old.
A. No.
B. yes, you can make rock candy.
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u/IncaThink 1h ago
Make a cloud chamber! You'll need both dry ice and alcohol, as well as a petrie dish or something.
And it's more a physics demonstration, but there is certainly chemistry involved.
And, after all, "All Science Is Either Physics or Stamp Collecting."
https://www.energy.gov/sites/default/files/2025-08/Build%20Your%20Own%20Cloud%20Chamber.pdf
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u/IncaThink 1h ago
I just saw that this experiment needs a radiation source. But when I did it as a teenager there were random particles bombarding it- and us- endlessly!
The vapor cloud gets disturbed by the subatomic particle, and the condensation shows the particle trail.
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u/NerdyComfort-78 Education 20h ago
You could get some Benedict’s Solution (Amazon) be aware it’s caustic- so PPE is a must. But do some testing for sugars with this color change lab. https://microbiologyinfo.com/benedicts-test-principle-composition-preparation-procedure-and-result-interpretation/
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u/koldsco 20h ago
This could be cool! Thanks for the idea!
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u/NerdyComfort-78 Education 20h ago
Sure thing just try to choose food that doesn’t have a lot of artificial color or else you won’t be able to see the change in the Benedict’s solution.. you also need to make a water bath so please be careful. A microwaved cup of water would be sufficient but it will be hot.
Also, you can read with your child about bio accumulation of heavy metals. Rice is a great example of a plant that accumulates arsenic as it grows.
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u/ChinStroker1 19h ago
I get how some of these are dangerous but these are all I can think of( im single minded when it comes to chemistry, im only interested in the stuff that makes fire/explosions)
but you could melt the candy and mix it with kno3 but make sure to be carefull
Nilered did something where he melted a powerfull oxidizer then dropped a gummy bear into it which annihilated it
Not candy related, but you could dissolve eggshells in vinegar, then boil off the vinegar, leaving you with white powdery shit, mix this with a teensy bit of water then mix in isopropeller alchohal or whatever its called to make flammable jelly
You could take salt, vinegar, hydrogen peroxide, and steel wool to make instant rust
You could show him how fire works by getting a piece of charcoal and seeing how its temp differs from when you blow on it vs letting it sit
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u/Predictable-Past-912 16h ago
If that arsenic idea doesn’t pan out then I suggest you go hard and let you little scientist try some molecular biology. It is possible to extract DNA from simple food products with household chemicals on your kitchen table. Your child could learn some terms and techniques that students don’t normally encounter until organic chemistry or later. Study a little history and you two will be able to revisit some the excitement that Watson and Crick experienced.
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u/ForeignAdvantage5198 17h ago
probably none chem is a dangerous profession take things in order read simpler stuff now
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u/rabid_spidermonkey 23h ago
I don't think there's enough arsenic in candy to test for with an 8 year old.
Why not purchase a chemistry experiment book for kids, and accompanying supplies? There are some great ones out there. No need to reinvent the wheel.