Question

Multi-Step Conversions (Always go through moles!)

Answer 1

Mass of water needed : 96.3 g

Further explanation  

A mole is a number of particles(atoms, molecules, ions)  in a substance

This refers to the atomic total of the 12 gr C-12  which is equal to 6.02.10²³, so 1 mole = 6.02.10²³ particles  

Can be formulated :

N = n x No

N = number of particles

n = mol

No = 6.02.10²³ = Avogadro's number

moles H₂O=

$\tt moles=\dfrac{N}{No}\\\\moles=\dfrac{3.22\times 10^{24}}{6.02\times 10^{23}}\\\\moles=5.35$

mass H₂O(MW=18 g/mol) :

$\tt mass=moles\times MW\\\\mass=5.35\times 18\\\\mass=96.3~g$