Question

Question #336a1

Answer 1

`5.018xx10^29` molecules of `H_2O`

Explanation:

According to mole concept :

1 mole of `H_2`0 = `6.022xx10^23` molecules of water = 18 gram `H_2`0

So 18 grams of `H_2O` = `6.022xx10^23` no. of molecules `H_2O`

And

150 grams of `H_2O` = `6.022xx10^23/"18"xx 150` molecules `H_2O`

= `5.018xx10^29` molecules of `H_2O`

Answer 2

`5.016326 * 10^24`

Explanation:

To calculate the number of molecules of a substance, we simply multiply the amount of moles by Avogadro's number, which is equal to `6.022 * 10^23`

But how many moles are in `150 g` of `H2O`?

Moles = Grams of a substance / Atomic Mass Of A Substance

Moles = `150g` / `18.015` (The atomic mass of two `H` is `2.016`. The atomic mass of `O` is `15.999`)

Moles = `8.33 mol`

Therefore there are `8.33 * 6.022 * 10^23` molecules. (`5.016326 * 10^24`)