Question

What is the mass of a sample of water containing 3.55×1022 molecules of h2o?

Answer 1

6,02×10²³ -------------- 18g
3,55×10²² --------------  x$x=\frac{3,55*10^{22}*18g}{6,02*10^{23}}=10,61*10^{22-23}g=10,61*10^{-1}g=1,061g$

Answer 2

Answer: The mass of water sample is 1.062 g

Explanation:

We are given:

Number of molecules of water = $3.55\times 10^{22}$

According to mole concept:

$6.022\times 10^{23}$ number of molecules are present in 1 mole of a compound

So, $3.55\times 10^{22}$ number of molecules will be present in = $\frac{1}{6.022\times 10^{23}}\times 3.55\times 10^{22}=0.059moles$ of water.

To calculate the mass of a substance, we use the equation:

$\text{Number of moles}=\frac{Given mass}}{\text{Molar mass}}$

Molar mass of water = 18 g/mol

Moles of water = 0.059 moles

Putting values in above equation, we get:

$0.059mol=\frac{\text{Mass of water}}{18g/mol}\\\\\text{Mass of water}=1.062g$

Hence, the mass of water sample is 1.062 grams