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La ciencia de la ensalada de macarrones: ¿qué hay en una mezcla? - Josh Kurz - Contenido educativo

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Subido el 4 de agosto de 2020 por Juan C. F.

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The world we live in is made of things. Billions and billions of different things, like pickles 00:00:00
and pianos and dump trucks and octopi. And even though these things seem totally different, 00:00:12
they're all made of the same stuff, just combined in different ways. To give you an idea of 00:00:17
how this combining works, let's take something apart. Let's start with this bowl of macaroni 00:00:21
salad. If you were to reverse a recipe for macaroni salad, you'll see it's made by mixing 00:00:26
together a bunch of ingredients, like macaroni, mayo, vinegar, vegetables, and mustard. This 00:00:31
type of combining is called a mixture. When you make a mixture, you're combining two 00:00:37
or more things together without actually changing the chemical identity of those things. Like 00:00:41
mud, for example. The soil and water in mud haven't actually changed. There's still 00:00:47
soil and water. You've just created a mixture of soil and water. Mud. It turns out that 00:00:53
But macaroni salad is actually a mixture of mixtures, because many of the ingredients, 00:00:58
like mayo and mustard, are already mixtures themselves. 00:01:03
Which is nice for us, because if we look closely, we'll see the three main types of mixtures 00:01:06
that exist. 00:01:10
The size of the particles in a mixture determines the type of mixture. 00:01:11
On one end of the scale is a suspension, like our muddy water example. 00:01:15
You get this if you take big chunks of something and mix it with something else so those chunks 00:01:19
are just floating around. 00:01:23
Take runny mustard, for example. 00:01:25
see a bunch of little particles like mustard seeds, pepper, allspice, and minced shallots 00:01:27
all floating around in a liquid. In this case, vinegar and water. This is called a suspension 00:01:31
because you've got particles of one thing suspended in another. Now, on the other end 00:01:36
of the spectrum is a solution. The particles in this mixture are so small, they are the 00:01:41
actual molecules. A solution is sort of like a suspension of molecules, where one type 00:01:45
of molecule is blended or dissolved with another. Vinegar is an example of a solution where 00:01:50
the molecules of acetic acid are blended with molecules of water. The chemical properties 00:01:55
of the molecules haven't changed, they're just evenly mixed together now. Salt water 00:02:00
and carbonated soda are both examples of solutions where other molecules are dissolved in water. 00:02:04
The last type of mixture is called a colloid, which is somewhere between a suspension and 00:02:09
a solution. It's when you take two materials that don't dissolve and you make the particles 00:02:14
so small that they can't separate. Mayo is what happens when you take oil and water, 00:02:18
don't mix, and you bind them together, usually with the help of another substance called 00:02:23
an emulsifier, in the case of mayo it's lecithin found in eggs, and now you're left with really 00:02:27
small globs of oil hanging out with really small droplets of water. Whipped cream, hair 00:02:32
spray, styrofoam, and jello are all other examples of colloids. So, let's get back to 00:02:37
macaroni salad. You've got colloids like mayo, suspensions like mustard, and solutions like 00:02:43
vinegar, but you've also got celery, shallots, and all other vegetable chunks that are also 00:02:48
part of the salad. These aren't mixtures, really, but we can break them up, just like a TV can be 00:02:52
broken up into smaller and smaller complex component parts. In the case of vegetables, 00:02:57
if you keep breaking things up, you'll eventually end with thousands of complex organic molecules, 00:03:01
things like ATP synthase, and RNA transcriptase, and water. So now, once we've unblended all the 00:03:06
solutions, unmixed all the colloids, separated all the suspensions, and taken apart all of our 00:03:15
vegetables, we've reached the end of what we can unmix physically. What we're left 00:03:20
with is a whole bunch of molecules, and these molecules remain chemically the 00:03:25
same whether they are by themselves or thrown together in a salad. If you want 00:03:29
to separate these guys even further, we need to unmix things chemically, which 00:03:33
means we need to start breaking some bonds. 00:03:38
Idioma/s:
en
Autor/es:
Josh Kurz
Subido por:
Juan C. F.
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
60
Fecha:
4 de agosto de 2020 - 19:20
Visibilidad:
Público
Enlace Relacionado:
https://ed.ted.com/lessons/the-science-of-macaroni-salad-what-s-in-a-mixture-josh-kurz
Centro:
IES CLARA CAMPOAMOR
Duración:
03′ 57″
Relación de aspecto:
1.78:1
Resolución:
1920x1080 píxeles
Tamaño:
28.93 MBytes

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