posted by Jack on .
An experiment that led to the formation of the new field of organic chemistry involved the synthesis of urea, CN2H4O, by the controlled reaction of ammonia and carbon dioxide.
2 NH3(g) + CO2(g)= CN2H4O(s) + H2O(l)
What is the theoretical yield of urea when 100. g of ammonia is reacted with 100. g of carbon dioxide?
This is a limiting reagent problem. I do those this way.
mols NH3 = grams/molar mass
mols C = grams/molar mass
Using the coefficients in the balanced equation convert mols NH3 to mols urea.
Do the same with mols C to urea.
It is quite likely these values will be different which means one of them is not right. The correct value for mols in limiting reagent problems is ALWAYS the smaller value and the reagent responsible for that is the limiting reagent.
Using the smaller value, convert mol urea to g. g = mols x molasr mass. This is the theoretical yield.