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Show that the percentages of nitrogen, by mass of the 3 compounds that are used in...

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thisisalongword | Student, Grade 11 | (Level 1) Salutatorian

Posted January 9, 2012 at 9:10 PM via web

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Show that the percentages of nitrogen, by mass of the 3 compounds that are used in fertilisers as a source of nitrogen:

Show that the percentages of nitrogen, by mass of the 3 compounds that are used in fertilisers as a source of nitrogen:

Ammonia (NH3) = 82.4%
Ammonium nitrate (NH4NO3) = 35.0%
Urea (CO(NH2)2) = 46.7%

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ndnordic | High School Teacher | (Level 2) Associate Educator

Posted January 10, 2012 at 6:01 AM (Answer #1)

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I will show you how to do the first compound, ammonia, and then you can use the same procedure for the other two.

First:

find the formula mass of the compound by finding the elemental mass of each element in the compound:

1 nitrogen atom * 14.01 g/atomic mass = 14.01 g

3 hydrogen atoms * 1.01 g/atomic mass  3.03 g

Second: add the elemental masses

14.01 + 3.03 = 17.04 g/mole of ammonia

Third:

Find the % of the desired element in the compound:

% N = 14.01 g Nitrogen/17.04 g of ammonia * 100 =82.2% N

Now you do the other two compounds using the same three step process.

 

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