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

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Answer 1 · 2017-10-06T15:49:33

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

#(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.

Answer 2 · 2017-10-06T16:07:25

#5.57times10^24 " H"# atoms

Glass contains #250 "g"# of water.

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

www.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