Question

How many moles of water are there in 1.000 l at stp? assume the density of water is 1000 kg/m3?

Answer 1

Assume 1 liter = 1 kilogram of water = 1000 grams of water.

Part A)
MW of hydrogen is 1.008g/mol, and oxygen is 16.00g/mol.

Find the MW of water by
2*(1.008) + (16.00) = 18.016g/mol.

Convert 1000g H2O to moles :

(1000g H2O)*(1mol H2O / 18.016g H2O) = 55.51 mol

Part B)
Using the answer from part A and Avogadro's number:

(55.51mol)*(6.022*10^23) =

3.343*10^25 molecules.
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