Calculate the mass of 20 water molecules. | vedclass

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Question

(A) The molar mass (gram molecular mass) of water $(H_2O)$ is $18 	ext{ g/mol}$.One mole of water contains $6.022 	imes 10^{23}$ molecules (Avogadro

Vedclass · Accepted Answer

$5.98 	imes 10^{-22} 	ext{ g}$

Vedclass · Answer

(A) The molar mass (gram molecular mass) of water $(H_2O)$ is $18 	ext{ g/mol}$.One mole of water contains $6.022 	imes 10^{23}$ molecules (Avogadro's number).Therefore,the mass of $1$ water molecule is calculated as:$	ext{Mass of } 1 	ext{ molecule} = \frac{	ext{Molar mass}}{	ext{Avogadro's number}} = \frac{18 	ext{ g}}{6.022 	imes 10^{23}} \approx 2.99 	imes 10^{-23} 	ext{ g}$.To find the mass of $20$ water molecules,we multiply the mass of one molecule by $20$:$	ext{Mass of } 20 	ext{ molecules} = 20 	imes 2.99 	imes 10^{-23} 	ext{ g} = 5.98 	imes 10^{-22} 	ext{ g}$.

Calculate the mass of $20$ water molecules.

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One mole of $H_{2}O$ means:
$(i)$ $18 \text{ g}$ of $H_{2}O$
$(ii)$ $6.022 \times 10^{23}$ molecules of $H_{2}O$
$(iii)$ $180 \text{ g}$ of $H_{2}O$
$(iv)$ $1.8 \text{ g}$ of $H_{2}O$

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