How many hydrogen atoms in a 250*g mass of water?

2 Answers
Oct 6, 2017

There are (2xx250*g)/(18.01*g*mol^-1)xx6.022xx10^23*mol^-1=....

Explanation:

(2xx250*g)/(18.01*g*mol^-1)xx6.022xx10^23*mol^-1=1.67xx10^25*"H atoms"

.....and HALF this number of "oxygen atoms".

Note that our calculation gave a dimensionless number, as required by the question.

Oct 6, 2017

5.57times10^24 " H" atoms

Explanation:

Glass contains 250 "g" of water.

Molar mass of water = 1times2+16=18g/"mol"

www.chemteam.infowww.chemteam.info

=>"Molecules of of water"=(N_A*"Mass")/"Molar mass"

=6.02*10^23 * (250g)/(18g/"mol") = 8.36times10^24

8.36times10^24 molecules of water has 2/3 " of " 8.36times10^24 atoms of Hydrogen.

2/3 " of " 8.36times10^24=2/3 times 8.36times10^24

=5.57times10^24 atoms of Hydrogen