Question

How many moles are in a 1.00-kg bottle of water? How many molecules? The molar mass of water is 18.0 g/mol.

Short answer

$0.055\times {10}^{3}mol$are present in a 1 kg bottle of water.

No. of molecules present is$3.35\times {10}^{25}$molecules.

Step-by-step solution

Moles present in water

No. of moles (n)

$$\begin{gathered} n=\frac{m_w}{M} \\ =\frac{1kg}{18\times {10}^{-3}kg/mol} \\ =0.055\times {10}^{3}mol \end{gathered}$$

$0.055\times {10}^{3}mol$are present in a 1 kg bottle of water.

Molecules present in water

No. of molecules$=n\times N_A$

Here,$N_A$is Avogadro Number and its value is $6.022\times {10}^{23}$molecules/mol

No. of molecules

$$\begin{gathered} =n\times N_A \\ =0.055\times {10}^3\times 6.022\times {10}^{23} \\ =3.35\times {10}^{25}Molecules \end{gathered}$$

No. of molecules present is $3.35\times {10}^{25}$molecules.