Need help with this question (see screenshot) Your answer is partially correct.
ID: 1731593 • Letter: N
Question
Need help with this question (see screenshot)
Your answer is partially correct. Try again. 2 Deuterium ( 1 ? ) is an attractive fuel for fusion reactions because it is abundant in the waters of the oceans. In the oceans, about 0.0155% of the hydrogen atoms in the water (H2O) are deuterium atoms. (a) How many deuterium atoms are there in one kilogram of water? (b) If each deuterium nucleus produces about 7.20 MeV in a fusion reaction, how many kilograms of ocean water would be needed to supply the energy needs of a large country for a year, with an estimated need of 7.00 x 1020 j? (a) NumberT 104000000000000000 11 Units || No units (b) NumberT585000000 Units kgExplanation / Answer
Solution ;
molar mass of water is 18 grams so in one kg of water there are
1000 grams water * 1 mole / 18 grams * 6.022x10^23 molecules / 1 mole = 334.56 x 10^23 molecules of water
there are two hydrogen atoms per molecule of water, so in 1 kg of water there are
2 * 334.56 = 669.11x10^23 hydrogen atoms
but only 0.0155% of these are deuterium so there are
0.000155 * 669.11 = 0.1037 x10^23 = 10.37 x 10^21 deuterium atoms in one kg of water
B)
so one kg of water can produce energy of
10.37 x 10^21 atoms * 7.20 MeV / 1 atom * 1.60x10^-13 Joules / 1 MeV = 1.195 x 10^10 Joules of energy
so a country would need
7 x 10^20 Joules * 1 kg / 1.195 x 10^10 Joules
= 5.86 x 10^10 kg of water
Comment in case any doubt please rate my answer ...