Formulations

Is most of a tube of toothpaste cheap padding around the fluoride? A typical tube says fourteen hundred and fifty parts per million of fluoride, and that's about a seventh of one per cent of what's in it. It's tempting to think the rest is filler, there to make the tube feel full. But almost everything else in there was put in on purpose, in a measured amount. What each of the other parts is doing comes at the end.

Not every course includes formulations, so check the screen, and if yours leaves them out, the next video for you is Chromatography and Rf values.

A formulation is a mixture that has been designed as a useful product. It's made by mixing its components in carefully measured quantities, and each component is in it for a purpose. So the definition has two halves, and both are needed: it's a mixture, and it's made in measured quantities to be a useful product. Now a check on the halves. A student writes: a formulation is chemicals added together to do a job. Which half is missing? The first half. It never says the result is a mixture, and a formulation is a mixture first. Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods. You never need the names of the components in a branded product. A table of them is there to be read, not learned. Alloys are on that list as metal mixtures made to a recipe, and why an alloy is harder than a pure metal is a later video's job. Plenty of mixtures aren't formulations at all, because nobody designed them. Now a sorting round: sea water, a paracetamol tablet, air, a bottle of shampoo, and a bag of plant fertiliser. Which two of the five are not formulations, and why not? Sea water and air. Both are mixtures, but neither was made in measured quantities to be a product. The tablet, the shampoo and the fertiliser were each designed, with every component measured in for a job. One examiner's report on a Higher paper describes the two halves going missing in turn. Several students knew it was a mixture but gave no reason for the mixture. And several knew substances were added together for a purpose, but didn't know the result would be a mixture. The fix is one sentence with both halves in it, every time: a mixture, made in measured quantities to be a useful product. Now a question about examples. Asked what a formulation is, a student writes: a paint. Does that answer it? No. A paint is an example of a formulation, not a definition of one. A report from an earlier year puts a number on it: twenty-two per cent of students knew the definition. Some could give examples, but not a definition. So when the question asks what a formulation is, give the two halves, and keep the examples for a question that asks for them.

A product label can now be read the way a question gives it. A sports drink lists water at ninety-four per cent and glucose at five per cent. Then sodium chloride at nought point four per cent, citric acid at nought point four per cent, and colouring at nought point two per cent. Is this a formulation? Answer in two parts, what it is and why it counts, and say what the sodium chloride is there for. Is it a formulation, and what are the two parts of your reason? Yes, it's a formulation. First, it's a mixture, because the substances are together but not chemically combined. And it's made in measured quantities, the percentages on the label, to be a useful product: a drink for exercise. The sodium chloride replaces the salt lost in sweat, so even a component at under half a per cent has a job. Now two tins of white gloss paint with the same pigment, but different amounts of solvent and binder. One dries in two hours and brushes out thin. The other takes a day to dry and covers in one coat. Why does the same pigment give two different products? Each paint is a formulation, and the quantities of solvent and binder were chosen differently, for different purposes. Change the quantity of one component and the properties of the product change, and that's why measured quantities are half the definition.

Now three to end on. A fertiliser lists three compounds in fixed percentages, made for growing crops.

Is the fertiliser a formulation or not, and why? A formulation. It's a mixture, made in measured quantities to be a useful product.

Now some pond water. Muddy pond water holds several substances. Is it a formulation? No. It's a mixture, but nobody measured its parts or designed it.

Now the full definition. What is a formulation? A mixture that has been designed as a useful product, made by mixing its components in measured quantities.

Back to the toothpaste. The grit polishes, the detergent foams and spreads it, a syrupy moistener stops it drying out, and the fluoride protects your teeth. Each part goes in at a measured amount, flavour included, so the tube holds a mixture designed to do a job. That's a formulation, and the part that isn't fluoride isn't padding.

If you can give both halves of the definition without stopping to think, this one's yours, so give it a thumbs-up. If not, leave it un-thumbed: it settles with a few questions.

Next in the chapter is Chromatography and Rf values. Hopefully that's next in your feed, but if not, search for ScholaFly C H oh three, oh six.

Every other video is on scholafly.com too, easy to search by video code or by keyword. Whatever you're revising, go there and have a look, or, watch the next video.