Question

How many water molecules does it contain? The density of water is 1.0 g/cm3.

Answer 1

Complete question is;

A drop of water has a volume of approximately 7 × 10⁻² ml. How many water molecules does it contain? The density of water is 1.0 g/cm³.

This question will require us to first find the number of moles and then use avogadro's number to get the number of water molecules.

Number of water molecules = 2.34 × 10²¹ molecules

We are given;

Volume of water; V = 7 × 10⁻² ml

Density of water; ρ = 1 g/cm³ = 1 g/ml

Formula for mass is; m = ρV

m = 1 × 7 × 10⁻²

m = 7 × 10⁻² g

from online calculation, molar mass of water = 18.01 g/mol

Number of moles(n) = mass/molar mass

Thus;

n = (7 × 10⁻²)/18.01

n = 3.887 × 10⁻³ mol

from avogadro's number, we know that;

1 mol = 6.022 × 10²³ molecules

Thus,3.887 × 10⁻³ mol will give; 6.022 × 10²³ × 3.887 × 10⁻³ = 2.34 × 10²¹ molecules

Read more at; brainly.in/question/17990661