Question #0de15

1 Answer
Apr 15, 2016

A_r=58.99Ar=58.99

Explanation:

The number of moles of a substance is given by:
(mass (grams))/("Relative atomic mass", A_r)mass(grams)Relative atomic mass,Ar

And one mole comprises (Avogadro's constant), N_A =6.022 times 10^23NA=6.022×1023 atoms / molecules.

So number of atoms is given by:
(mass (grams)*N_A)/("Relative atomic mass", A_r)mass(grams)NARelative atomic mass,Ar

In this case

((16.26times 10^-3g)/A_r)*(6.022 times 10^23)=1.66 times 10^20(16.26×103gAr)(6.022×1023)=1.66×1020

Rearranging gives:

A_r= (16.26times 10^-3g)*(6.022 times 10^23)/(1.66 times 10^20)Ar=(16.26×103g)6.022×10231.66×1020
so
A_r=58.99Ar=58.99