Question

1) 4.25 x 1022 atoms Ni = _g Ni

Answer 1

Answer:

Mass of Ni = 4.14  grams

Explanation:

Molar mass : It is the amount of substance present in 1 mole of the molecules.

Moles : It is the quantity that contains as many atoms as present in 12 gram of C-12. This is equal to Avogadro Number .

$Avogadro\ Number= N_{0}$

$N_{0}=6.022\times 10^{23}$

Molar mass of Ni = 58.69 g/mole

Moles can be calculated by two formula:

$moles(n)= \frac{given\ mass(m)}{Molar\ mass(M)}$

$n=\frac{m}{M}$........(1)

And ,  

$moles=\frac{Number\ of\ atoms(N)}{N_{0}}$

$n=\frac{N}{N_{0}}$.........(2)

Comparing equation 1 and 2

$\frac{m}{M}=\frac{N}{N_{0}}$

$N = 4.25\times 10^{22}$

$N_{0}=6.022\times 10^{23}$

M = 58.69 g/mole

Put these value in the formula and solve for m

$\frac{m}{58.69}=$

$\frac{4.25\times 10^{22}}{6.022\times 10^{23}}$

$\frac{m}{58.69} = 0.0705$

$m=58.69\times 0.0705$

m = 4.14 gram

Mass of Ni = 4.14  grams

Second Approach :

Find the moles first using :

$n=\frac{N}{N_{0}}$

Then put value of n in the formula(1) and solve for m

$n=\frac{m}{M}$........(1)