Infographic on the chemical history of tinsel, charting the use of silver pre-1900, aluminium and lead from 1900 onwards, and PVC in the present day
For the final day of #ChemAdvent24, we take a look at the chemical history of tinsel, from lead (yikes) to present-day plastic 🎄
#ChemSky 🧪
A small, cute elf-like figure, smiling with eyes closed, standing in front of lots of bright pink tinsel
Day 24 #ChemAdvent24: it’s tinsel time!
Lead foil was once used for tinsel as it doesn’t tarnish, but poisoning fears led (heh) to its replacement with polyvinyl chloride (PVC) film with a metallic finish of aluminium, which also doesn’t tarnish due to the unreactive oxide that forms on its surface
Infographic on turkey chemistry, showing the structures of some of the molecules (furans, furanones, parasites and thiophenes) formed by the Maillard reaction and which contribute to its flavour.
Day 23 of #ChemAdvent24 looks at the flavour chemistry of Christmas turkey 🦃
Ours is already dry brining in the fridge ready for Wednesday
#ChemSky 🧪
A roasted turkey breast on a plate surrounded by vegetables
Day 23 of #ChemAdvent24 🍗
The Maillard reaction happens between amino acids (in proteins) and certain sugars. It causes browning and produces lots of flavour compounds. The temp needs to be over ~120°C and the food’s surface dry—hence steaming doesn’t cause browning, but roasting does, yum!
And day 21's @thamesvalleyrsc.bsky.social student chemistry advent covered Christmas puddings, which are coincidentally covered by day 22 of #ChemAdvent24
Infographic on Christmas pudding, showing the chemical structures of tartaric acid from raisins and citric acid from citrus peel. It also notes the tradition of including small silver coins in the mixture for luck and how this is not possible with modern coins due to the change in coin composition
Making Christmas pudding is a common British tradition at Christmas - but changes in coin metal compositions mean you're better off avoiding the tradition of including a coin in the mixture for luck, as day 22 of #ChemAdvent24 explains
#ChemSky 🧪
A Christmas pudding, set alight with a blue flame
Day 22 of #ChemAdvent24!
Traditionally we pour brandy on Christmas pudding and set it alight. The flame is blue/almost invisible because the oxygen in the ethanol means combustion
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
is near-complete and few carbon particles form—it’s these that make flames yellow
Infographic on eggnog showing the structures of two key flavour compounds, cinnamaldehyde and sabinene, from the cinnamon and nutmeg used to make it
For day 21 of #ChemAdvent24, we look at some flavour compounds from the spices used to make eggnog, a popular festive drink
#ChemSky 🧪
A photo showing cups of egg nog in front of a bottle labelled “Egg Nog”
Day 21 (!) of #ChemAdvent24…
Eggnog is made with vanilla, which contains vanillin, C₈H₈O₃. Demand for vanilla flavour has exceeded supply (of beans) for a long time, so modern vanillin is synthesised. Funnily enough it was first made from eugenol, found in cloves—another common eggnog ingredient!
Infographic on mince pies, showing the chemical structures of tartaric acid and eugenol, two key flavour contributors
Day 20 of #ChemAdvent24 brings us mince pies! Despite the name, they don't contain mince, but dried fruits and spices, which contribute fruit acids and a variety of flavour compounds
A baking tray filed with (fruit) mince pies, some topped with a pastry star, some not
For 20 of #ChemAdvent24 🥧
Modern mince pies are meatless, containing only dried fruit. Dried fruits are darker than fresh, partly due to formation of furfuraldehydes (of which furfural is one, see day 19!) as sugars break down. SO₂ reduces this effect, so is added to fruits to preserve colour.
Infographic on the aroma of roast chestnuts showing the structures of furfural and gamma-butyrolactone, two key contributors to the aroma
For day 19 of #ChemAdvent24, we look at the compounds behind the delicious smell of roast chestnuts
#ChemSky 🧪
[Now with less Christmas magic pentavalent carbon]
A photo of chestnuts roasting in giant pans over flames
Day 19 of #ChemAdvent24 🌰
When chestnuts are roasted flavour compounds form, including furfural, C₄H₃OCHO, which has a woody scent and is also found in bran, coffee and wholegrain bread. Industrially, furfural is an important starting material; it’s one of the oldest renewable chemicals!
Infographic on christmas crackers highlighting the role of the friction-sensitive explosive, silver fulminate, the structure of which is shown
I'm a bit late with day 18 of #ChemAdvent24 but it's a cracker... a Christmas cracker, that is, and the friction-sensitive explosive behind their festive explosions 💥
A silver Christmas cracker resting on a white plate on a red tablecloth
Day 18 of #ChemAdvent24 💥
Cracker snaps contain silver fulminate, AgCNO. It’s an explosive, but not practically useful due to its sensitivity to heat, impact and pressure: a single water drop is enough to ignite a 5p-sized pile of silver fulminate! It’s also toxic, so don’t eat crackers 😉
Infographic on the relighting candle trick. Several diagrams show a candle being relit via its smoke trail, giving the illusion of the flame jumping back down to the wick. This is due to the wax vapour in the smoke trail
Another chemistry dinner table trick for day 17 of #ChemAdvent24: Relighting candles at a distance thanks to wax vapour 🕯️
A photo of red candles burning in a Christmassy setting
Day 17 of #ChemAdvent24 🔥
There’s more to flames than you may think. They appear when gaseous fuel and oxygen mix and a very exothermic reaction takes place. Around the wick are non-luminous and dark zones; the bit we see is the luminous zone, and around that is the even hotter ‘non-luminous veil’
Infographic on holly and ivy, showing the chemical structure of theobromine, the toxic alkaloid found in holly berries, and the structure of falcarinol, the irritant found in ivy leaves
Day 16 of #ChemAdvent24 looks at two seasonal plants
Did you know that holly contains a toxic alkaloid compound also found in chocolate?
And that different types of ivy can be skin irritants as a result of different compounds?
Photo of red holly berries on a branch among green, spiky leaves
Day 16 of #ChemAdvent24!
Holly ‘berries’ are technically drupes. They’re important food for wild animals but toxic to humans—due to the bitter, vomit-inducing alkaloid ilicin—and to cats and dogs, mainly due to theobromine and caffeine. But they can also be used to make a rare kind of fruit brandy!
Infographic on flammable orange peel oils, showing the chemical structure of limonene
For day 15 of #ChemAdvent24, here's a flammable chemistry trick you can do at the Christmas table 🔥
#ChemSky 🧪
A slice of orange among Christmassy things
Day 15 of #ChemAdvent24 🍊
Orange peel contains D-limonene. It’s flammable, hence squeezing peel at a candle produces a good flame! It’s also used as a fragrance in cleaning and cosmetic products, and as a pesticide. And it’s an excellent solvent: it’s a nicer-smelling alternative to turpentine!
Infographic on the aroma of frankincense, showing the structures of isomers of olibanic acid, key contributors to the aroma.
For day 14 of #ChemAdvent24, a look at the compounds behind the distinctive aroma of frankincense, with isomers of olibanic acid the most important
#ChemSky 🧪
Photo of amber-coloured lumps: Boswellia sacra, Oman, Frankincense
Day 14 of #ChemAdvent24!
Frankincense (olibanum) is from Boswellia trees. Its main component is an acid resin C₂₀H₃₂O₄ which has two slightly different structures, and these've been shown to produce the distinctive odour. Frankincense has also been studied for possible neuroprotective activity.
Infographic on cranberry antioxidants. Cranberries are high in polyphenol antioxidants, such as quercetin, and as a consequence have a reputation as a health food. Lab tests have shown quercetin and related compounds in cranberries to have anti-cancer effects, but evidence for these effects in humans is currently limited, and more research is required. Cranberry juice is often suggested as a treatment for urinary tract infections, but reviews of several studies have shown it provides no benefits compared to a placebo.
For day 13 of #ChemAdvent24 we're looking at cranberries and scrutinising the reported health benefits of their antioxidant compounds
A white plate of bright red cranberries in front of green Christmas tree-like foliage
Day 13 of #ChemAdvent24
Cranberries and extracts are believed to have health benefits, but evidence is slight. Reviews’ve concluded they don’t cure UTIs but might help reduce recurrent infections. As with many bright fruits, the juice changes colour with pH. Cranberry jelly’s nice with turkey, too!
Infographic on bell metals. Usually, these are alloys of copper and tin with other trace elements making up the balance. Some trace elements, such as phosphorus and sulfur, can make a bell more susceptible to cracking.
For day 12 of #ChemAdvent24, we're looking at the sonorous metals that allow the bells to ring out for Christmas Day
#ChemSky 🧪
Small cold-coloured bells hanging by chains from a ceiling
Day 12 of #ChemAdvent24 🔔 🎶
Bells! Metals are sonorous: they ring when hit. Bell metal is usually a bronze alloy with 20–25% tin. This makes it more rigid, allowing vibrations to travel easily and increasing resonance. The alloy is harder and more impact-resistant than either copper or tin
Infographic on winter fires, showing some of the compounds responsible for the smell of burning wood. These include guaiacol, 4-methylguaiacol, syringol and isoeugenol.
For day 11 of #ChemAdvent24 we're cosying up to a warming winter fire and enjoying some of its smoky-smelling compounds 🔥
#ChemSky 🧪
Close-up photo of a log burning in a fire
Day 11 of #ChemAdvent24 🔥
Doesn’t a log fire smell great? The smoke contains many compounds: syringol and guaicol have sweet, smoky scents, while isoeugenol is more woody – this one is also used in ‘liquid smoke’ and is one of the key compounds known to inhibit mould in ‘cured’ meat and cheeses 🥓🧀
Infographic on wrapping paper and tape, both of which are cellulose based (the structure of cellulose is shown). Tape also contains a pressure-sensitive acrylic or synthetic rubber-based adhesive
For day 10 of #ChemAdvent24 we take a look at a compound that both wrapping paper and tape have in common 🎁
#ChemSky 🧪
