主题：【求助】分子量，还是分子量

I prefer molecular weight.

From NIST :

……The terms atomic weight and molecular weight are obsolete and thus should be avoided. They have been replaced by the equivalent but preferred terms relative atomic mass, symbol Ar, and relative molecular mass, symbol Mr, respectively [4: ISO 31-8]……
(see 8.4 at http://physics.nist.gov/Pubs/SP811/sec08.html )

However, the term “molecular weight” is still used in NIST webbook (see  http://webbook.nist.gov/chemistry/mw-ser.html ).  I think that “relative molecular mass” may be more scientific, but the traditionally used term “molecular weight” is still acceptable.

今天看了一个英文资料，上面是 mass
个人还是倾向于mass
资料名称： 分析化学中的仪器技术（手册）  chapter 12  IC 

欧盟的法规网站（应该算是比较权威了的吧），某物质的MSDS中是这样写的：


molecular weight

原文由 poorlittle(poorlittle) 发表:
I am a layman in chemistry.  However, if I have to choose between “mass” and “weight”, I prefer “mass” because “weight” involves the gravitational acceleration in general physics (W=m×g).

But when I was in high school, it was called “Molecular Weight”

It is said “为了避免质量和重量的混淆，所以，国际计量大会建议在科学用语中，取消重量概念。”  (please refer to 28#, http://bbs.instrument.com.cn/shtml/20110712/3410991/index_3.shtml )

It was over 40 years ago when I learnt the term “Molecular Weight” in high school.  During that time, we also frequently used公斤 instead of千克.



Would 欧盟的法规 change later?

All the three terms are different:

molar mass = 摩尔质量 = the mass of 1 mole substances (unit = kg/mol or g/mol)

molecular weight = 相对分子质量 = the ratio of the mass of the molecule to 1/12 of the mass of carbon 12.Since it is a ratio, it has no unit.

molecular mass =分子量/分子质量 = the mass of a single molecule/atom (unit = amu or Da, 1amu = 1/12 mass of a C-12 atom)

However, some of the terms are already outdated. Molecular weight is a ratio instead of "weight". It has been replaced by "relative molecular mass".

In Chinese, 分子量 was actually used to represent "molecular weight", therefore, the terms has been regulated as 相对分子质量.

There are more complicated stories behind molecular mass. Therefore, contemporary science is avoiding to use this term any more.

Actually, the value of molecular weight = molecular mass. The differences are just on the definitions and the units.

原文由 poorlittle(poorlittle) 发表:

原文由 poorlittle(poorlittle) 发表:
I am a layman in chemistry.  However, if I have to choose between “mass” and “weight”, I prefer “mass” because “weight” involves the gravitational acceleration in general physics (W=m×g).

But when I was in high school, it was called “Molecular Weight”

It is said “为了避免质量和重量的混淆，所以，国际计量大会建议在科学用语中，取消重量概念。”  (please refer to 28#, http://bbs.instrument.com.cn/shtml/20110712/3410991/index_3.shtml )

It was over 40 years ago when I learnt the term “Molecular Weight” in high school.  During that time, we also frequently used公斤 instead of千克.



Would 欧盟的法规 change later?

40 years ago, SI units were not introduced yet. After the adoption of SI units, the use of kilo-, mega-, giga-, etc. has been standardized.