Question

how many hydrogen atom in 9 gram of H2O molecules

Answer 1

Water has 18 grams per mole so 9 grams is 0.5 moles of water.

There are 6.022* 10^23 molecules in a mole.

Each water molecule contains *one* oxygen and *two* hydrogens.

SO! We have

0.5*(6.022*10^23) * 1 oxygens = 3.011 * 10^23 oxygens

~~~~~~~~AND~~~~~~~~

0.5*(6.022*10^23) * 2 hydrogens = 6.022 * 10^23 hydrogens

in 9 grams of water.

Answer 2

1 mole of water=18g

So, 9g water =0.5mole

1mole water contains 2*6.022 x 10^23 Hydrogen atoms

0.5 mole will contain (2*6.022*10^23) x 0.5=6.022 x 10^23 atoms(ans)