Ok, Need some more help... This is what I have so far.
4. Urea (NH2)2CO is prepared by reacting ammonia with carbon dioxide. The byproduct is water. 637.2g of ammonia are reacted with 787.3 g of carbon dioxide.
molar mass:NH3=17 CO2=44 CO(NH2)2=60.1
a. (10 points) Write a balanced chemical equation.
2NH3+CO2--->CO(NH2)2 +H20
Is this right?
b. (5 points) Determine which of the two reactants (ammonia or carbon dioxide) is a limiting reactant. Show
calculations to support your choice. No credit will be given if your supporting calculations are wrong.
2 moles NH3 is require 1 mole of CO2 to produce one molecule of CO(NH2)2. 2 moles NH3 is 637.2/17=37.5 moles =37.5/2=18.74 moles in 1 NH3?
Available CO2 = 787.3 = 787.3/44=17.89 moles CO2 So since CO2 is smaller, wouldn't it be the limiting agent?
c. (10 points) Which of the two reactants should you use to calculate the theoretical yield (= the maximum amount
possible) of urea? Explain why. UMMM I would calculate the NH3 because it is the larger one? why? I don't have a clue help?
Answered above.
a. The balanced chemical equation is correct: 2NH3 + CO2 ---> (NH2)2CO + H2O
b. To determine the limiting reactant, we need to calculate the number of moles of each reactant and compare their stoichiometric ratios. Your calculations are almost correct, but there's a small mistake in calculating the moles of NH3.
Correct calculation:
- Moles of NH3 = 637.2 g / 17 g/mol = 37.48 mol (You rounded it to 37.5, which is fine)
- Moles of CO2 = 787.3 g / 44 g/mol = 17.89 mol
Now, comparing the stoichiometric ratio:
- For the balanced equation, we need 2 moles of NH3 for every 1 mole of CO2.
- Moles of NH3 / 2 = 37.48 mol / 2 = 18.74 mol (You previously wrote this value for moles of NH3 incorrectly)
Since we have fewer moles of CO2 (17.89 mol) than the required 18.74 mol of NH3, CO2 is indeed the limiting reactant.
c. To calculate the theoretical yield of urea, we need to use the stoichiometric ratio from the balanced equation and the moles of the limiting reactant. In this case, since CO2 is the limiting reactant, we should use the moles of CO2.
The moles of CO2 (17.89 mol) will determine the maximum amount of urea that can be produced according to the balanced equation. Using the molar mass of urea (60.1 g/mol), we can calculate the theoretical yield.
Theoretical yield of urea = Moles of CO2 × Molar mass of urea
Theoretical yield of urea = 17.89 mol × 60.1 g/mol = 1074.49 g
Therefore, the theoretical yield of urea is 1074.49 grams.