Question

how do i use the atomic mass unit (amu) to find the mass of an Ar atom?

Answer 1

@Sheng @Preetha can u plz help

Answer 2

Well, there are many instances that you will use atomic mass. Could you be more specific? I use the atomic mass generally for conversions at the moment. Determining what "1 mol" of something is requires the atomic mass.

Answer 3

For example: Finding what 1 mol of NaCl2 would be adding the atomic mass of (1) Na and (2) Cl. So you look to your periodic table for the mass of each and add them.

(1) Na= 22.989769g (2) Cl= 35.453 x 2

So one mol of NaCl2 is equivalent to 93.895769 grams

Answer 4

http://chemwiki.ucdavis.edu/Physical_Chemistry/Atomic_Theory/Atomic_Mass

Answer 5

how to use the amu for finding the mass of an Ar atom ?

Answer 6

Wouldn't the amu of Ar (39.948) divided by Avogadro's number be the mass of one atom of Ar?
I may be wrong...

Answer 7

no, 39.948 is the mass of 1 mol Ar

Answer 8

this is just ONE atom, so it will be so much smaller

Answer 9

first convert one atom to mol

1 atom Ar x (1 mol)/(6.022 x 10^23)

Answer 10

39.948/6.02214179(30)×1023, right?

Answer 11

*^23
sorry

Answer 12

after you convert to mol, you can then convert it to grams using 39.948

Answer 13

one sec, lemme do the math

Answer 14

so how do i use the amu in the end
is it like the following

Ar atom mass= 39.9g (1.66 x 10^24 kg/ 1 amu )

Answer 15

ok i will wait

Answer 16

1.00 atom Ar = 1.66 x 10^-24

Answer 17

mol

Answer 18

1.66 x 10^-24 mol x (39.948g)/(1 mol) = 66.3 x 10^-24g

Answer 19

i believe...

Answer 20

i think that is right but why is 1.66 x 10 ^24 MOL and not kg

Answer 21

because we had to convert atom to mole, then mole to grams

Answer 22

in the back of my book it says 1 amu = 1.66 x 10^24 g

Answer 23

i'm not sure :/ i learned that 1 mole = 6.022 x 10^24 atoms.

Answer 24

yeah that is right

Answer 25

but u did not use the amu so what is the point

my question is how do i use the amu in this situation

Answer 26

:/ sorry.

Answer 27

it is ok thanku for trying

Answer 28

This is from the Wikipedia:

"In chemistry and physics, the Avogadro constant (symbols: L, NA) is defined as the number of constituent particles (usually atoms or molecules) in a mole of the substance. It is a dimensionless number and has the value 6.02214129(27)×1023 mol−1

So wouldn't the amu of Ar (39.948 g / mol) divided by 6.02214129(27)×1023 mol−1 be the mass of one atom of Ar?

Answer 29

no i already know how to use that rule but my teacher gave an example of finding the mass of an Ar atom and he used the amu value not the avogardo's number

avagardo's number is supposed to be used when i want know the mass of one mole of Ar atoms not just one Ar atom

Answer 30

Hmmm... Do you have an answer sheet? If so, what does it say?

Answer 31

i have the answer but i wanted to make sure and i think i copied it wrong

i have 39.95 g x 1.66 x 10^24 g = 6.63 x 10^ 26

Answer 32

it would just be 10^24?

Answer 33

it is ok i think i have the wrong answer though