Question

The density of water at 4.00°C is 0.967 g/mL. How many molecules of water are present in a 499.8 mL bottle of water? Express your answer to the correct number of significant figures. Be sure to show all steps completed to arrive at the answer.

Answer 1

Density of water at 4.00^oC is 0.967 g/mL . Volume of water = 499.8 mL

Mass of water =$density \times volume = 0.967 \times 499.8=483.3066 g$

Number of moles of water molecules in given mass of water =$\frac{given mass}{molar mass}= \frac{483.3066}{18}=26.85$

we know that 1 mole has $6.022\times 10^{23}$ molecules of water

so,

number of water molecules=$6.022\times 10^{23} \times 26.85=161.69\times 10^{23}=1.62 \times 10^{25}$ molecules of water. It is upto 3 significant figure.