Plus or minus %10 how many tons of Hydrogen are in the Earth's Oceans?

pdy-ga,


The best scientific estimates put the mass of the world's oceans at
about 1.37 x 10^21 kg:



http://hypertextbook.com/facts/1998/AvijeetDut.shtml
Mass of the Oceans




The average salinity of the oceans is 35 parts per thousand:


http://www.palomar.edu/oceanography/salty_ocean.htm
...Throughout the world, the salinity of sea water averages about 35 o/oo


or 3 1/2% salt.  Therefore, the oceans are 96.5% water, and amount of
water in the oceans is:


96.5% of 1.37 x 10^21 kg = 1.32 x 10^21 kg.


Each molecule of water is (by weight, and on average) 16 parts oxygen
and 2 parts hydrogen, so that water is:


2/16 = 1/8th = 12.5% hydrogen.



12.5% of 1.32 x 10^21 kg = 0.165 x 10^21 kg = 1.65 x 10^20 kg.



Therefore, there are 1.65 x 10^20 kg of hydrogen in the world's
oceans, which can also be expressed as 1.65 x 10^17 metric tons.


I trust that's what you needed.  However, if there's anything else I
can do for you, just let me know by posting a Request for
Clarification.

And thanks for a fun question!

pafalafa-ga



search strategy -- Google searches on:

volume oceans

average salinity oceans

---

Clarification of Answer by pafalafa-ga on 17 Apr 2006 07:37 PDT

Thanks to palitoy-ga for politely pointing out an error in my
calculations, which -- though small -- is certainly not an
insiginificant one.

The corrected calculations are:


==========
Each molecule of water is (by weight, and on average) 16 parts oxygen
and 2 parts hydrogen, so that water is:


2/18 = 1/9th = 11.1% hydrogen.



11.1% of 1.32 x 10^21 kg = 0.147 x 10^21 kg = 1.47 x 10^20 kg.



Therefore, there are 1.47 x 10^20 kg of hydrogen in the world's
oceans, which can also be expressed as 1.47 x 10^17 metric tons.

==========


Again....let me know if there's anything else you need on this.

paf

Just a minor correction to pafalafa-ga's reasoning which is obviously
a typo on his part - water is approximately 16 parts oxygen and
approximately 2 parts hydrogen by atomic mass.  Hydrogen atoms
therefore make up 2/18 of the mass and not 2/16 as stated.