How many grams of water are in 4.589 x 10^23 molecules of water (h2o)? okay i'm trying this by every mole to gram method for an hour and still can't solve pl me

Answer is: 13.7 grams of water.

N(H₂O) = 4.589·10²³; number of water molecules.

n(H₂O) = N(H₂O) ÷ Na(Avogadro constant).

n(H₂O) = 4.589·10²³ ÷ 6.022·10²³ 1/mol.

n(H₂O) = 0.76 mol; amount of substance.

M(H₂O) = 2 · Ar(H) + Ar(O) · g/mol.

M(H₂O) = 2 · 1 + 16 · g/mol.

M(H₂O) = 18 g/mol; molar mass of water.

m(H₂O) = n(H₂O) · M(H₂O).

m(H₂O) = 0.76 mol · 18 g/mol.

m(H₂O) = 13.7 g.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.