Unit Conversion & Significant Figures: Crash Course Chemistry #2

A unit is the frequently arbitrary designation we have given to something to convey a definite magnitude of a physical quantity and every quantity can be expressed in terms of the seven base units that are contained in the international system of units. Hank thinks this is a thrilling subject, and while you may not agree, it is a subject that is very important if you want to be a scientist and communicate with accuracy and precision with other scientists. So listen up and learn something or Hank might have to kill you! (NOT REALLY!)

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Table of Contents
Unit Conversion 02:27
Scientific Notation 03:26
Sig Figs 07:40

• Category

  Education

[Andrew Becker]

and afterwards we'd Barium.

[Sebastian Muñiz]

I think the a very BIG idea behind a kilogram is being completely missed here: 1 Kg = 1 cubic decimeter of water at 273 kelvin degrees. So, you can be really sure that a 1 cubic meter of water has 1000 liters (since 1 liter = 1000 cubic centimeters). Make yourself a big favor and start _thinking_ in international units.

[BlackMagicProd]

In the video, see 1:14 - 1:23. Hank doesn't really cover temperature in this episode, but the absolute unit is included at least.

[Sebastian Muñiz]

I see.. I didn't know that. I put the degree word in order to stress I was speaking of temperature; but didn't know Kelvin was the unit itself.

[BlackMagicProd]

"Kelvin degrees" aren't a thing. The correct way to say that would be "273 kelvin," not "kelvin degrees." Kelvin are an absolute unit, as Hank mentioned in the video. If we're going to think in international units, we should think them correctly.

[animalzamzam]

And you know what we do to liars in chemistry? We kill them

[pcljet]

Regarding the notation at 10:00 about rounding conventions: there are some conventions that would round to 300 and not 310, including one used by some engineers which rounds to the even number when the closest dropped term is a 5. That is, both 295 and 305 would round to 300 and both 315 and 335 would round to 320.

However, the exact rounding convention being used seems to be as much a matter of personal preference as standards, so I will leave my statement at that.

[LawnPygmy]

80085

[RawMaths]

At around 2m40s it is said that a second is defined as 1/60 of 1/60 of 1/24 of the time it takes for the earth to rotate a single time, but I believe that it only takes 23 hours and 56 minutes for the earth to rotate once on its axis and one day is actually the time it takes for the sun to appear at the same point in the sky from one day until the next!

[Antony Hamilton]

That's actually an approximate number, not really exact. Also, stop lying, because water at 273 degrees kelvin would be ice. You know what we do with liars in chemistry?

>video

[Charles Yip]

boobs@5:29

[EpicGamerBot]

Yah