Learn About Using the Liter in Chemistry Courses

[brycenrg]

I'm taking my 3rd chem course and I was just wondering why do we use the Liter?
Shouldn't we just use cm^3 on the instruments and use dm^3? I never got it.

 

[fresh_42]

I'm taking my 3rd chem course and I was just wondering why do we use the Liter?
Shouldn't we just use cm^3 on the instruments and use dm^3? I never got it.

Since a liter is $1000 cm^3$ or $1 dm^3$ it doesn't make a difference. Liter is allowed within the SI system so it's just a matter of taste.

 

[Dr. Courtney]

Tradition?

It's not too hard to go back and forth between metric units. 1 L = 1000 cm^3.

 

[Ygggdrasil]

It's also easier to convert between different orders of magnitude (the relationship between L, mL, µL is more apparent than between cm^3, dm^3 etc).

 

[brycenrg]

For a sec I thought order of magnitude was a good enough reason but then I realized when you use maths you don't ever use liter, you convert it to cm^3. So it doesn't make it easier :( lol I guess it's just our primordial slime

 

[Ygggdrasil]

Chemists and biochemists typically do a lot of math involving L. For example, today in lab, I had to figure out how many µL of specific solution (whose concentration was in mg/mL) to get a final concentration of 10 µM in a 20µL reaction. Not impossible to do in terms of cm^3 etc, but using the L system helps a little.

 

[Borek]

I realized when you use maths you don't ever use liter, you convert it to cm^3

In some areas mL (or c³) is preferred over liter, in others it is not.

In general, you choose a unit that is most convenient to use.

I wouldn't say my car burns 7500 mL gasoline per 100 km, I would say it needs 7.5 L per 100 km.

The volume of gas collected at STP when you decompose 1 mole of CaCO₃ is commonly listed as 22.4 L, not 22400 mL.

And the hydrogen tanks of the LZ 129 Hindenburg had a volume of about 200 000 m³, I wouldn't report it neither using L nor mL.

 

[epenguin]

If you look in old textbooks till the 1950's or so I think you will find cc's. I don't know the exact history and the whys of it, but I did see the changeover mnyah mnyah. In the years of school up to English 'O level' (around age 16) I remember nothing but cc's. But then the next two years ('A levels) from the start it had switched over entirely to litres and ml.

I think, at least this is my memory, if you look into scientific book reviews for 10 or 20 years around that time, you'll find them a very often saying 'the MKS system is used' or 'unfortunately the CGS system is used' (or maybe if they were reactionary the other way round). I guess this was important for school purchasing decisions. I seem to remember we had books with both systems; as the conversion is so easy it never bothered me, in fact I never saw what the fuss was about

 

[ogg]

Most of the world uses the liter as THE measuring unit of ( human use size) volume. When is the last time you measured a liquid by measuring its (container's) length, width and height? Who does that? When I was in school, warning! ancient history alert!, the liter was NOT exactly 1000 cm^3, believe it or not. Anyway. You can easily measure volumes (liquids and gasses) in terms of intuitive units of volume, whether gallons or liters, cups or barrels. It requires a bit of abstract thinking to understand that a cubic cm is a unit of volume. Also, (and while this may seem like a restatement of the previous, it really is different) using what to a lot of people is the same unit for length, area, and volume (ie the meter or the centimeter) would cause confusion. It takes some training to understand that multiplying cm x cm does NOT result in cm. If you really think about it, can you explain why cm x cm = cm² ? (Hint: the directions of the basis vectors are orthogonal...but why do you get ANYTHING meaningful when you multiply two orthogonal vectors? And why should we assume that as soon as the "same" units are multiplied, the bases (abstract coordinate system) are orthogonal? See, its a rat hole, better left to those geeks amongst us who can do algebra, etc.

 

[rootone]

A typically full human bladder contains about a liter.

 

[DrClaude]

When I was in school, warning! ancient history alert!, the liter was NOT exactly 1000 cm^3, believe it or not.

I actually did not believe you, because the original definition of the liter after the French revolution was dm³. But you are right! from 1901 to 1964, the liter was defined based on the properties of water, so it was about 1.000028 dm³. Learned something today...

 

[Borek]

I actually did not believe you, because the original definition of the liter after the French revolution was dm³. But you are right! from 1901 to 1964, the liter was defined based on the properties of water, so it was about 1.000028 dm³. Learned something today...

Actually I was taught of liter not being exactly 1000 cm³ somewhere in mid seventies. Probably because it took time for the altered SI definition to seep down.

 

[Rx7man]

I actually did not believe you, because the original definition of the liter after the French revolution was dm³. But you are right! from 1901 to 1964, the liter was defined based on the properties of water, so it was about 1.000028 dm³. Learned something today...

While it's not exact, you're still accurate to 5 significant digits...
The meter is also defined as a portion (is it 1/1,000,000) of the distance from the equator to the north pole?.. A second is also defined as a period of the Earth's rotation (1/(24*60*60)), but the Earth's rotation is measurably slowing down, so either you keep the time period of the old definition and most everyone is happy, or you change it, and every physics constant involving time will have to be recalculated. Just as a year isn't exactly 365 days, a day is not exactly 86400 seconds, and THERE ARE LEAP SECONDS every once in a while.

 

[Borek]

The meter is also defined as a portion (is it 1/1,000,000) of the distance from the equator to the north pole?

Why don't you google that instead of guessing? No, it was never a part of the distance from the equator to the north pole (even if the equator was definitely involved).

 

[Rx7man]

It was in fact.. It was a 10 millionth from the equator to the north pole according to wiki
https://en.wikipedia.org/wiki/Metre

 

[Borek]

Sigh, you learn all your life and you die stupid I swear I was taught it was 1/40000000 of the equator length.

Honestly, I feel like in those films where someone learns he doesn't exist and nobody recognizes him. It was always the equator based definition! Have you edited everything in the world just to make me feel like an idiot?

 

[pbuk]

Most of the world uses the liter as THE measuring unit of ( human use size) volume.

Most of the world calls it a litre.

Sigh, you learn all your life and you die stupid I swear I was taught it was 1/40000000 of the equator length.

Honestly, I feel like in those films where someone learns he doesn't exist and nobody recognizes him. It was always the equator based definition! Have you edited everything in the world just to make me feel like an idiot?

I assume the French, who invented the metre chose their prime meridian as the defining circumference because it passes through Paris whereas the equator does not.

 

[Rx7man]

Sigh, you learn all your life and you die stupid I swear I was taught it was 1/40000000 of the equator length.

Honestly, I feel like in those films where someone learns he doesn't exist and nobody recognizes him. It was always the equator based definition! Have you edited everything in the world just to make me feel like an idiot?

If you're talking about my post, I only edited it for styling and spelling... I didn't edit Wikipedia though.

As for the spelling of meter/metre.. Being in Canada I should abide by the international spelling, but it doesn't make any sense phonetically... If I were speaking french I'd be fine with Metre because then it's phonetically correct.

 

[epenguin]

Sigh, you learn all your life and you die stupid I swear I was taught it was 1/40000000 of the equator length.

Honestly, I feel like in those films where someone learns he doesn't exist and nobody recognizes him. It was always the equator based definition! Have you edited everything in the world just to make me feel like an idiot?

Ah, but if the Earth were spherical it would be exactly the same thing. Perhaps in seventeen ninety-noo they thought it was.

 

[sophiecentaur]

Most of the world calls it a litre.

and they also call a metre a metre. A meter is a measuring instrument and a liter is not part of SI, afaiaa. Liter is, presumably, and Americanism, which is a bit of a librety as they don't even use the damn thing.

 

[fresh_42]

and they also call a metre a metre. A meter is a measuring instrument and a liter is not part of SI, afaiaa. Liter is, presumably, and Americanism, which is a bit of a librety as they don't even use the damn thing.

There are several non SI units which are allowed to use along side the SI system. The liter is one of them.

 

[sophiecentaur]

There are several non SI units which are allowed to use along side the SI system. The liter is one of them.

HAHA. They are only allowed because of usage and inertia and because Europeans are so polite to strangers . It doesn't make them right, though. One of these years, people will start to spell things correctly, put the U in colour, the I in aluminium and the d in pedantry.
But I would have thought that the right spelling would be appropriate in a discussion about SI units. Is there any objection to spelling the units according to the System?

 

[Zachary Smith]

If you're talking about my post, I only edited it for styling and spelling... I didn't edit Wikipedia though.

As for the spelling of meter/metre.. Being in Canada I should abide by the international spelling, but it doesn't make any sense phonetically... If I were speaking french I'd be fine with Metre because then it's phonetically correct.

Focus on the centre of your argument.

 

[fresh_42]

But I would have thought that the right spelling would be appropriate in a discussion about SI units. Is there any objection to spelling the units according to the System?

As English isn't my nature language I follow the spell-check. I don't know whether it's within the platform or the browser. Unfortunately it seems to be an American one. However, it supports my laziness. It simply takes too much time to type words like 'Pittsborough'.

 

[sophiecentaur]

As English isn't my nature language I follow the spell-check. I don't know whether it's within the platform or the browser. Unfortunately it seems to be an American one. However, it supports my laziness. It simply takes too much time to type words like 'Pittsborough'.

If you rely on a spell check to get your Scientific terms right then you risk serious problems at some stage. A spell check is not a sense check and I have a feeling that not many Scientists actually get into writing dictionaries and encyclopediae. Pittsborough may still be a real place on a map and, if the Americans chose to rename their own town Pittsburgh then I will spell it the way they write it on their maps. "Too much time"? There's always time for doing what we want to do (he said, whilst glancing at Facebook and checking his mail).

 

[Zachary Smith]

Proofreading is the cornerstone to successful text messages.
.

 

[sophiecentaur]

Proofreading is the cornerstone to successful text messages.
.

Keep 'em coming!

 

[fresh_42]

If you rely on a spell check to get your Scientific terms right then you risk serious problems at some stage. A spell check is not a sense check and I have a feeling that not many Scientists actually get into writing dictionaries and encyclopediae. Pittsborough may still be a real place on a map and, if the Americans chose to rename their own town Pittsburgh then I will spell it the way they write it on their maps. "Too much time"? There's always time for doing what we want to do (he said, whilst glancing at Facebook and checking his mail).

We call your 'litre' 'Liter' and it happens to be the same way the Americans spell their 'liter'.
Therefore I think I have some right to spell it 'liter' as well.
To call the French 'litre' as witness to consolidate your case I will start to take into account the moment you start to follow Napoleon's regulation and drive on the right side of the road.

 

[sophiecentaur]

We call your 'litre' 'Liter'

But it isn't 'my litre', it's the litre of SI (lower case l), which is the language for communicating in Science.
When in the UK, drive on the left. When in Europe etc. drive on the right. When in Science, use the appropriate language - to avoid misunderstanding. milli and Mega both use an 'emm' but the case has to be right or you fly into the side of a hill.
If someone can't be bothered to follow conventions in units then can they be relied on to follow the conventions of algebra, calculus and geometry? Science and Maths only work when people take stuff seriously. I am only attacking the spelling - not the spellers. Despite everything, you are probably all perfectly nice chaps and do not kick dogs, beat wives or put your elbows on the table.

 

[fresh_42]

But it isn't 'my litre', it's the litre of SI (lower case l), which is the language for communicating in Science.

I am sorry, but the usage of SI does not overrule the rules of language. To derive a frowsy habit on scientific care is ridiculous, if not offensive. Conventions, even those on units, are not context-free. E.g. the meaning of 1 billion differs from country to country. By the way, why did the British changed its usage? Because the colony did?

 

[Ygggdrasil]

But it isn't 'my litre', it's the litre of SI (lower case l), which is the language for communicating in Science.
When in the UK, drive on the left. When in Europe etc. drive on the right. When in Science, use the appropriate language - to avoid misunderstanding. milli and Mega both use an 'emm' but the case has to be right or you fly into the side of a hill.

The style guide for the American Chemical Society, which publishes many major journals in chemistry such as JACS, prefers liter over litre.

 

[sophiecentaur]

I am sorry, but the usage of SI does not overrule the rules of language. To derive a frowsy habit on scientific care is ridiculous, if not offensive. Conventions, even those on units, are not context-free. E.g. 1 billion differs from country to country. By the way, why did the British changed its usage? Because the colony did?

No offence intended but I would say that SI does overrule the local conventions of the vernacular, in Scientific discussion. If not, then how approximate are we allowed to be (in the context of Science) before we start to affect the communications channel.? Apart from in a sloppy news item, who would use the term "billion" if they wanted to get across the number 10⁹ accurately? The history of the term "billion" doesn't interest me but I do use context when reading financial news. Context would not work if astronomical distances were being described in billions. Using the 'small' billion makes sense because there is such a massive jump between 10⁶ and 10¹².
"Context": People often make assumptions about what is meant by c,t,T,W,E,V,A etc but when you want to be understood unequivocally, you need to state, formally, what each letter stands for. I don't see a problem with trying to stick as close as possible to the conventions in the constext of PF.
We do not accept txt speak, for the same reasons.

 

[sophiecentaur]

The style guide for the American Chemical Society, which publishes many major journals in chemistry such as JACS, prefers liter over litre.

Noted and accepted. (I don't have access to it, I'm afraid)
I wonder why, orignally they had a problem with a 'foreign' word. Because it started off as 'litre'.
Some of my best friends are Chemists so they can't be all bad.

 

[fresh_42]

You are right as I won't use my local 'AE' instead of 'AU', however, I can't consider it as a big deal whether someone is writing 'liter' instead of 'litre'. After all it's an American website. (And the 'big step' argument between 10⁶ and 10¹² is not valid as there is a term for 10⁹, too, in the long scale definition.)

 

[Ygggdrasil]

Noted and accepted. (I don't have access to it, I'm afraid)
I wonder why, orignally they had a problem with a 'foreign' word. Because it started off as 'litre'.
Some of my best friends are Chemists so they can't be all bad.

To be fair the IUPAC prefers litre. Anyway, there are no situations I can think of where using litre or liter would cause any type of confusion, so it's probably not a very important point (compare to the example of billion which can sometimes mean 10^9 or 10^12). The different spelling conventions of US vs UK English are annoying (I remember a labmate having to spend a day reformatting him manuscript to British spelling so that he could submit it to Nature), but in most cases are unlikely to cause any sort of confusion or ambiguity in scientific communication.

 

[Zachary Smith]

Here is one that should baffle nobody here, but did, many years ago at school. The problem starts with a rope around the Earth at the equator. How much more rope would you need to lift the rope off the ground by a foot all the way around the world?

 

[vanhees71]

Well, nowadays the litre (or liter for the Americans ;-)) is defined as just $10^{-3} \,\mathrm{m}^3$ (I guess since the 1960ies), but before it was the volume of 1 kg of water at maximum density at normal pressure (which it takes at a temperature of around $4^{\circ} \mathrm{C}$), and this is a tiny bit more than $10^{-3} \mathrm{m}^3$.

 

[sophiecentaur]

After all it's an American website.

I think PF prides itself on being very International. If it weren't, this conversation wouldn't be happening. And that's a good point. People who read this site are often not familiar with 'English'. Unexpected spellings can add uncertainty where it's not needed.

there is a term for 10⁹,

What is that?

 

[fresh_42]

I think PF prides itself on being very International.

Fine. But that comes to the prize that not all of us are able to speak a perfect British English. Me, e.g.

If it weren't, this conversation wouldn't be happening.

Inadmissible conclusion.

And that's a good point. People who read this site are often not familiar with 'English'. Unexpected spellings can add uncertainty where it's not needed.

That is why I use the spell checker, it reduces my mistakes. To distinguish between American and British spelling is in my opinion a little too sophisticated. Once a scientist said to me in a very staccato way: "Scientific English is broken English." I don't remember where he was from.

What is that?

1 milliard = 10⁹
1 billiard = 10¹⁵
1 trilliard = 10¹⁸
etc.
Wiki says the British have been using this until they went short like the Americans do.

 

[sophiecentaur]

British spelling

The word "litre" is not British. It was invented and used long before the British stopped using the fps system. I am not being propriatorial about this; I am just in favour of as much standardisation as possible in scientific spelling and symbolism. The fact that people have problems with 'foreign' terms shouldn't get in the way of that.
Milliard etc rings a bell. I seem to remember something in our 'lads talk'. I also remember hearing the 'big' million being referred to as a decimal million.
It is interesting that the Imperial unit system is still alive and well in the US. I believe that SI is starting to make inroads, though.

"Scientific English is broken English."

I have heard similar comments. But I'm not offended. In fact I am very attracted by some of the expressions and words used in Americal English - it flows more freely than the pukka (Indian word) version.

 

[fresh_42]

But I'm not offended.

Well, it hasn't been intended as an offense. To be honest I share your feelings what has happened to your language. Mine is loosing its depths nowadays. I learned English at school and it makes me insecure each time the spell checker becomes red when I talk about a colourful neighbourhood. It's then when I realize the differences. Eventually you may have recognised I was quoting John Cleese's "Letter to America" in spirit by talking about Pittsborough. However, meanwhile my conversations in English are almost all with Americans, including those with my nephews. This is one reason the spell checker's 'liter' appears more natural to me. If I read 'litre' I cannot prevent from pronouncing it french which makes it kind of artificial in the middle of an English sentence.

 

[vanhees71]

Well, if you prefer the British spelling, just switch your spell checker (system wide, if possible) to British English. Where's the problem?

Concerning the billion-billiard problem, it's very easy to just say not to use it. If you read old texts it's important to know, what the meaning of these words was at the time and place when the text was written. Just use the SI decimal symbols and/or the scientific notation of numbers.

 

[sophiecentaur]

It isn't "the British spelling"; the way round to put it is that "liter" is the "American Spelling'.
I am quite surprised (wake up, Sophiecentaur!) that the spellchecker is used as the final arbiter for spelling for you guys. Having had to fight, for years, with strange Microsoft ideas about how things should be spelled (irrespective of which dictionary I select), I tend to look elsewhere for the best fit. Actually, a Google search can often give a good page full of hits with different ideas about versions of spelling.

To be honest I share your feelings what has happened to your language. Mine is loosing its depths nowadays.

The way to keep ahead is to do a lot of reading of non-tech books. English language novels by American or English authors are a good source of well thought out sentence construction, vocabulary and spelling. I was always very disappointed with the reactions of my often more technically able colleagues to the idea of that idea. ("Booring". I ask you.)
Hey - we seems to have hijacked this thread well and truly. I don't think I have actually voiced an opinion on the philosophy and practice of standardising units. . . . yet.
Still, it has been interesting and none of us has thrown toys out of their pram about the subject.

 

[Ygggdrasil]

I am quite surprised (wake up, Sophiecentaur!) that the spellchecker is used as the final arbiter for spelling for you guys.

It is not, which is why I cited the style guide for the American Chemical Society.

 

[arydberg]

Sigh, you learn all your life and you die stupid I swear I was taught it was 1/40000000 of the equator length.

Honestly, I feel like in those films where someone learns he doesn't exist and nobody recognizes him. It was always the equator based definition! Have you edited everything in the world just to make me feel like an idiot?

Wikipedia is riddled with errors. Here is some information on the definition of meter

From:
http://dictionary.reference.com/browse/meter
I get

meter definition

The basic unit of length in the metric system; it was originally planned so that the circumference of the Earth would be measured at about forty million meters. A meter is 39.37 inches. Today, the meter is defined to be the distance light travels in 1 / 299,792,458 seconds.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition

Copyright © 2005 by Houghton Mifflin Company.

Published by Houghton Mifflin Company. All rights reserved.

Cite This Source
Be very careful about believing anything on Wikipedia. Most of what they say is more what is generally accepted but has little to do with truth.

 

[sophiecentaur]

It is not, which is why I cited the style guide for the American Chemical Society.

I should have called it the routine arbiter and not the final one. The spell checker was certainly mentioned in several of the posts. It's good for spotting typos but little else and gives a false sense of security. That's my problem with it. One stage worse, of course, is predictive text which needs proofreading for even the shortest message.

 

[Borek]

it was originally planned so that the circumference of the Earth would be measured at about forty million meters

While it refers to the definition I remember, it doesn't contradict what wiki says about the subject. "About forty million" is perfectly in line with the meridional definition listed as original.

No, I don't trust wiki, but in this case the claim seems to be reasonably well supported by the references listed.

 

[sophiecentaur]

No, I don't trust wiki,

No one should trust them completely but in matters like this and where the word "approximately" is involved - plus a good justification- it's not going to be horribly wrong, is it?
It's not hard to do some sums to justify it, in any case.