Question

How many molecules of water are in 345g

Answer 1

1.15 molecules

Step-by-step explanation:

To get to molecules, you need to first convert grams into moles, then moles into molecules.

345g of water x
`(1 mol )/(18.02g)`

This will get you the moles of water. (The number 18.02 came form the molar mass of water which is H2O)

I MOLE EQUALS AVOGADRO'S NUMBER

19.15 mol of water x
`(6.022*10^(23)molecules )/(1 mol)`

= 1.15

Answer 2

There are
`1.1542* 10^(25)` molecules of water are in 345 grams.

Step-by-step explanation:

`n=(m)/(M)`

`N=n* N_A`

Where:

m = mass of compound

M = Molar mass of compound

N = Number of particles / atoms/ molecules

n = Number of moles

`N_A=6.022* 10^(23) mol^(-1)` = Avogadro's number

Mass of water = m = 345 g

Molar mas of water = M = 18 g/mol

`n=(345 g)/(18 g/mol)=19.167 mol`

Number of molecules of water = N

`N=19.167 mol* 6.022* 10^(23)mol^(-1)`

`N = 1.1542* 10^(25) molecules`

There are
`1.1542* 10^(25)` molecules of water are in 345 grams.