Stoichiometry question number 5 (last one)?

Question

Note- please do not just solve these for the answer, but give a brief explanation as to how you got them, so I can refresh my memory on how to do this branch of Chemistry again. Thanks!!!

5. Your Body deals with excess nitrogen by excreting it in the form of Urea, NH2CONH2. The reaction producing it is the combination of Arginine (C6H14N4O2) with water to give urea and ornithine (C5H12N2O2).

C6H14N4O2 +H2O --> NH2CONH2 +C5H12N2O2

if you excrete 95 mg of urea, what quantity of arganine must have been used? what quantity of ornithine must have been produced?

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thanks so much!!

Answer 1

1. Calculate the molecular weight of urea and convert the 95 mg into moles.

2.  Based on the reaction equation it's 1:1 mole ratio between all components, so that you will use the same number of moles of arganine as the number of moles of urea excreted in #1.  Just convert the moles back to grams of arganine, using its molecular weight.

3.  the quantity of ornithine produced is the same number of moles as in #1 and #2, and again just convert that into grams with its molecular weight.  (M.W. can be calculated from individual atomic weight loated in the table of elements for each molucule, for example, water, H2O molecular weight is the sum of the weights of each element: 2x2g + 16 grams = 18 grams/mol)