Question: how many molecules are in each sample 6.5g h2o?
Answer: This means that 1 mole of water weighs 18 grams. Therefore x = (6.5x1)/18 = 0.361 moles. We have 0.361 moles, so: 0.361 x 6.022141 x 10 = 2.174 x 10 molecules.