Question

Calculate
(1)mass of 1.0505×10²³molecules of Co2
(2)the no.of moles in 0.25 mole of NH3
(3) the formula unit mass of Na2So3

Answer 1

Ans

(1) given mass/molar mass=no.of molecules/Avogadro's no.

m/44=1.0505×10^23/6.022×10^23

m/44=1.0505/6.022

m=1.0505×44/6.022

m=7.67g

(2)no.of moles =No.of molecules/Avogadro's no.

0.25=no.of molecules/6.022×10^23

no.of molecules=0.25×6.022×10^23

no.of molecules=1.5055×10^23

(3)Mass of Na=23u

Mass of S=32u

Mass of O=16u

therefore mass of Na2SO3=

(2×23)+32+(3×16)

Mass of Na2SO3=46+32+48=126u.

hope it helps...

Answer 2

${\huge {\mathfrak {\red {Answer :-}}}}$

$<b>$1. There is a mistake in your typing. It will be 1.505 * 10^23. Please correct it.

Answer is 11 gms.

2. 1.505 * 10^23 molecules.

3. Mass of Na2SO3 = 126 u.

Refer to the attachment. ⬆️ ⬆️

$</b>$ That's it..