If 10000001000000 silver atoms weigh 1.79 xx 10^(-16) "g"1.79×1016g, what is the atomic mass of silver?

1 Answer

The atomic mass of silver is "107.87 amu"107.87 amu or "g/mol"g/mol.

Explanation:

Actually, atomic mass is a relative mass of an atom of an element and is represented by the ratio of actual mass of an atom of the element to the mass of 1/12112th part of a ""_6^12 "C"126C atom.

So atomic mass is a "unitless" quantity. But actual mass of an atom is not unit-less quantity.

The mass of 1/12112th of a ""_6^12 "C"126C atom is taken as a unit of mass and is known as 1 amu or 1 u .

"1 u" = 1/(N_A) g=1.66xx10^-24 g1 u=1NAg=1.66×1024g,

where N_ANA is Avogadro's Number.

Example

When we write atomic mass of "Na"Na, it is "22.989 amu"22.989 amu for one atom, or "22.989 g/mol"22.989 g/mol in general.

When we write mass of one atom of "Na"Na, it is:

"22.989 amu" xx (1.66xx10^-24 "g")/"1 amu" = 3.82xx10^-24 "g"22.989 amu×1.66×1024g1 amu=3.82×1024g for one atom of "Na"Na.

Now the answer of the given question

Let the atomic mass of silver be M_"Ag"MAg.

So one atom of silver weighs:

M_"Ag" "amu" xx (1.66xx10^(-24) "g")/"1 amu" = 1.66xx10^(-24)M_"Ag"MAgamu×1.66×1024g1 amu=1.66×1024MAg "g"g

10^6106 atoms of silver weighs:

= 1.66xx10^-24M_"Ag"=1.66×1024MAg "g"g xx 10^6 = 1.66xx10^-18 M_"Ag"×106=1.66×1018MAg "g"g

Equating this with the given value we can write:

1.66xx10^-18 M_"Ag"1.66×1018MAg "g"g = 1.79xx10^-16 "g"=1.79×1016g

:. M_"Ag" = 1.79/1.66xx10^2~~"107.87 amu" or "g/mol"

You can see this conversion work:

"107.87 amu" = 107.87/(6.022xx10^(23)) "g", as stated at the top.

Therefore...

107.87/(cancel(6.022xx10^(23))) "g" xx (cancel(6.022xx10^(23)))/"mol"

= "107.87 g/mol"

So, the atomic mass of Silver is "107.87 amu" or "g/mol".

Please inform if not clear.