Question

Chemistry Honors:
Calculations Involving a Limiting Reactant
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:
2NH3(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?

Answer 1

i got it thx. :p

Answer 2

dang... i typed up this whole thing...

Answer 3

sorry ill give u a medal for it :3

Answer 4

ok well im going to post it anyways for other people

Answer 5

haha thanks

Answer 6

the synthesis of urea contributed to the formation of organic chem? O.o wow... haha well this is a basic stoich problem. the conventional way to do it is to solve for two cases, one with 100g of ammonia and excess carbon dioxide and the other is to solve with 100g of carbon dioxide ad excess ammonia and see which of the two reactions produces less product (thus your limiting reactant). In my calculations im going to round quite a bit, your chem professor will expect better "sig figs" then that.
so the molar masses of each is roughly 44 for CO2, 17 for NH3, 60 for urea, and 18 for water.

we start with 100g of co2, divide it by the molar mass to get the molar amount given and end up with 2.3 ish. so we know that 100g of co2 is 2.3 moles of it. well we know that 1 mole of co2 with excess ammonia makes 1 mole of urea so 2.3 moles must make 2.3 moles of urea.

what if we start with 100g of ammonia? well 100g of ammonia divided by its molar mass gives us about 5.9 moles of ammonia. since two moles with excess co2 makes one mole of urea then 5.9 moles must make 2.95 moles of urea.

we can see that if we only have 100g of both, then we will only end up with 2.3 moles of urea since there isint enough co2 to make more (even though there is enough ammonia).

Answer 7

wow thats a lot haha :)

Answer 8

i dont like using the "fence" equations for dimensional analysis because students often dont understand why they work. i would rather type up and explanation so that you can see WHY you do all that math :P

Answer 9

an explanation*

Answer 10

yeah, but i usually like it if you show me how to do it
that's what my teacher does anyways =)

Answer 11

like work out the problem xD

Answer 12

**i can do that** if you need, but you said you already got it haha. plus the actual math is in the explanation so it just takes some reading haha

Answer 13

ok thx o-o but i think it would be easier and less time consuming if you worked out the problem

Answer 14

iight

Answer 15

did you solve this task or not?

Answer 16

yeah, haha :)