- #1
IB
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The textbook told me that there's a relationship between the amu and the gram, but I fail to see any. Could you please show me? Thank you.
What is the relationship between the amu and the gram?
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Discussion Overview
The discussion revolves around the relationship between atomic mass units (amu) and grams, exploring their definitions, conversions, and implications in the context of mass measurement in chemistry and physics.
Discussion Character
- Conceptual clarification
- Debate/contested
- Mathematical reasoning
Main Points Raised
- Some participants note that both amu and grams are measures of mass, with specific numerical relationships provided, such as 1 amu equaling approximately 1.66053886 × 10-24 grams.
- One participant expresses confusion regarding the equivalence of 1 gram to 6.022 × 1023 amu, questioning the derivation of this relationship and its connection to the definition of amu as 1/12th the mass of a Carbon-12 atom.
- Another participant emphasizes that definitions of units like amu are context-specific and that amu serves as a convenient unit for atomic-scale masses.
- It is suggested that the relationship between grams and amu is convenient in that the mass of a mole of an atom or compound in grams is numerically similar to its mass in amu, linking this to the historical context of the mole's development.
Areas of Agreement / Disagreement
Participants express varying degrees of understanding and confusion regarding the relationship between amu and grams, with no consensus reached on the clarity of the conversion or its implications.
Contextual Notes
Some limitations in the discussion include the dependence on specific definitions of mass units and the unresolved nature of the mathematical relationships presented, particularly regarding the mole and its historical context.
- #2
dav2008
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They are both are a measure of mass.
1 atomic mass unit = 1.66053886 × 10-27 kilograms = 1.66053886 × 10-24 grams. You can look this value up in books/online pages.
You can derive it by realizing that 1 amu is defined as 1/12th the mass of a C-12 atom.
1 atomic mass unit = 1.66053886 × 10-27 kilograms = 1.66053886 × 10-24 grams. You can look this value up in books/online pages.
You can derive it by realizing that 1 amu is defined as 1/12th the mass of a C-12 atom.
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- #3
IB
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dav2008 said:
But how is 1g of anything = 6.022 X 10^23 amu
Isn't 1 amu = 1/12 Carbon-12 so therefore 6.022 X 10^23 amu = 6.022 X 10^23 amu / 12 Carbon-12 ?
I'm quite confused. Where did chemists get 1g of anything = 6.022 X 10^23 amu.
- #4
dav2008
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A lot of things are defined in respect to very specific situations. For example, the second is defined as "9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom". The meter is defined as "the length of the path traveled by light in absolute vacuum during a time interval of 1/299,792,458 of a second".
That doesn't mean that we are restricted to using seconds only when talking about cesium atoms, or using meters only when talking about how far light travels.
The amu is just a convenient unit to use when talking about things with mass on the scale of atoms. (And those things are typically atoms)
That doesn't mean that we are restricted to using seconds only when talking about cesium atoms, or using meters only when talking about how far light travels.
The amu is just a convenient unit to use when talking about things with mass on the scale of atoms. (And those things are typically atoms)
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- #5
GCT
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It's somewhat convenient, the relation between grams to amu that is, in the sense that the value in amu of a particular atom/compound is pretty much the same with the mass of a mole of that atom/compound. Thus reading up on the history of moles, and why it was created, should add some excitement to this matter, that of the relationship between the mass of an individual atom/compound with that of a sample. The whole thing was somewhat devised, that is they were seeking for such a method of gravimetric analysis, and that's why the "mole" is so special.
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