Question

1.
Calculate the number of moles for the
following:
(i) 52 g of He (finding mole from
mass)
(ii) 12.044 x 1023 number of He atoms
(finding mole from number of
particles).​

Answer 1

❄️ Solution :

No. of mass = n

Given mass = m

Molar mass = M

Given number of particles = N

Avogadro number of particles = $\sf N_0$

(i) Atomic mass of moles

$\sf \: = \: \pink{ \dfrac{given \:mass}{molar \: mass} } \\ \\ \implies \sf \: n = \frac{m}{M} = \frac{52}{4} = \pink{13}$

(ii) we know,

1 mole = 6.022 × 10²³

The number of moles

$\sf \: = \pink{ \dfrac{given \: number \: of \: particles}{ Avogadro~ number }} \\ \\ \implies \sf \: n \: = \frac{ N }{N _0} = \frac{12.044 \times 10 {}^{23} }{6.022 \times 10 {}^{23} } = \pink{ 2}$