Question

Find out the mass of 10^21 molecules of Cu.

Answer 1

Answer:

We know that 1 Mole of copper is 63.5g.

Therefore we need to find the number of moles.

Since 1 Mole is 6.022 x 10^23 molecules.

Therefore, 10^21 molecules is 10^21/(6.022 10^23)

i.e 1.66 x 10^(-2) moles.

Hence, mass of 10^21 moles is,

(1.66 x 10^(-2) x 63.5 )

= 0.105 Grams.

Answer 2

Answer:

0.105 (approx)

Explanation:

n = given mass/molar mass = mass/ 63.5

n = no of particles/ avogadro no = $10^{21}$/6.022*$10^{23}$

equating both sides,

mass/63.5 = $10^{21}$/6.022*$10^{23}$ ;

mass*6.022*$10^{23}$ = $10^{21}$*63.5

mass*60.22*10 = 63.5

mass = 63.5/60.22*10 = 0.105 (approx)

hope this helps!