What is the actual mass of a water molecule?

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(B) The molar mass of water $(H_2O)$ is $18 \ g/mol$.According to the mole concept,$1 \ mol$ of water contains $N_A$ (Avogadro's number,$6.022 	imes

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$2.99 	imes 10^{-23} \ g$

Vedclass · Answer

(B) The molar mass of water $(H_2O)$ is $18 \ g/mol$.According to the mole concept,$1 \ mol$ of water contains $N_A$ (Avogadro's number,$6.022 	imes 10^{23}$) molecules.Therefore,the mass of $N_A$ molecules of water is $18 \ g$.The mass of $1$ molecule of water is calculated as $\frac{18}{N_A} \ g$.Substituting $N_A = 6.022 	imes 10^{23}$,we get $\frac{18}{6.022 	imes 10^{23}} \approx 2.99 	imes 10^{-23} \ g$.

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