Question

A scientist has 207.45g of H2O in a beaker. How many water molecules are in the beaker?

Answer 1

6.94 x 10²⁴molecules

Step-by-step explanation:

Given parameters:

Mass of water = 207.45g

Unknown:

Number of molecules = ?

Solution:

To solve this problem, we must understand:

1 mole of a substance contains 6.02 x 10²³ molecules

Now, first find the number of moles of water;

Number of moles =
`(mass)/(molar mass)`

Molar mass of water = 2(1) + 16 = 18g/mol

Number of moles =
`(207.45)/(18)` = 11.53moles

So;

1 mole of a substance contains 6.02 x 10²³ molecules

11.53moles of carbon dioxide will contain 11.53 x 6.02 x 10²³

= 6.94 x 10²⁴molecules