Question #336a1

2 Answers
Jul 31, 2017

Answer:

#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#

Jul 31, 2017

Answer:

#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#)