Question

How many moléculas of Water are there there in 54g of H2O

Answer 1

Answer:

mass of 1 mole of water = 1 × 2 + 16

                                          =2+16

                                         =18 gm

no.of moles in 54 gm of water = mass in grams of water÷molar mass

                                                                                                 

                                                   = 54÷18

                                                    = 3

∵no. of molecules in mole = 6.023 × 10²³

∴  no. of molecules in 3 mole = 3× 6.023 × 10²³

                                                    = 18.069 × 10²³      

hope this may help you

                 

Answer 2

Answer:

Number of molecules of water in 54g water = 18.066 * 10²³

Explanation:

We know that,

Number of moles = $\dfrac{Given \ mass}{Molar \ mass}$

Number of moles = $\dfrac{Number \ of \ molecules}{Avogadro \ number}$

Therefore,

$\dfrac{Given \ mass}{Molar \ mass}$ = $\dfrac{Number \ of \ molecules}{Avogadro \ number}$

Given that,

Given mass = 54g

Molar mass = (1*2) + (16*1)

                   = 2 + 16

                   = 18g

Avogadro number = 6.022 * 10²³

Substituting these values in we get,

$\dfrac{54}{18} = \dfrac{Number \ of \ molecules}{6.022 \times 10^{23}}$

$Number \ of \ molecules = 3 \times 6.022 \times 10^{23}$

Number of molecules = 18.066 * 10²³