Question

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?

Answer 1

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"`.