What are (a) the number of molecules in a water drop whose mass is #0.05*g#; (b) the number of hydrogen atoms in such a drop; and (c) the number of oxygen atoms?

1 Answer
anor277
Jun 12, 2017

We know that #18.01*g# of water is a molar quantity that contains #6.022xx10^23# individual water MOLECULES......and thus we can answer each question quantitatively..........

Explanation:

#a.# #"Molecules of water in a rain drop"# #=# #(0.05*g)/(18.01*g*mol^-1)xx6.022xx10^23*mol^-1=1.67xx10^21*"water molecules"#

#b.# #"Hydrogen atoms in a rain drop"# #=# #"TWICE the number of water molecules"# #2xx1.67xx10^21*"hydrogen atoms"#.

#c.# #"Oxygen atoms in a rain drop"# #=# #"THE SAME NUMBER as the number of water molecules"# #1.67xx10^21*"oxygen atoms"#.

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