Question #b64d1
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"How does Bohr improve Rutherford's atomic model?"
MW is 18 grams per mol (for water). In 27 grams of water there are #9.03times10^23# molecules of water.
Water has molecular weight of 18 grams per mol (remember that hydrogen atomic weight is 1 and oxygen atomic weight is 16 grams and water formula is #H_2O#).
1 mole of water contains #6.02times10^23# molecules.
If you have 27 grams of water, it means you have #27/18 = 1.5# moles of water.
If you have 1.5 moles of water, it means #1.5times6.02times10^23# water molecules are in it.
When you do the multiplication, you will get
1.5 moles of water contain #9.03times10^23# molecules of water.
#9.03 xx 10^23 "Molecules"#
Recall #-> "no of moles" = "No of Entity"/"Avogadro Constant"#
Also #-> "no of moles" = "mass"/"molar mass"#
Water #-> H_2O#
#"Mass of" color(white)(x) H_2O -> 27g#
#"Molar mass of" color(white)(x) H_2O -> (1 xx 2) + 16 = 2 + 16 = 18gmol^-1#
#:. "no of moles of" color(white)(x) H_2O = (27cancelg)/(18cancelgmol^-1)#
#"no of moles of" color(white)(x) H_2O = 1.5mols#
But # "No of Entity" = "no of moles" xx "Avogadro Constant"#
Hence #"No of Entity (Molecules)" = 1.5 xx 6.02 xx 10^23#
#"No of Entity (Molecules)" = 9.03 xx 10^23 "Molecules"#
