Respuesta :
Answer:
NH3 is the limiting reactant
The % yield is 36.1 %
Explanation:
Step 1: Data given
Mass of NH3 = 2.15 grams
Mass of O2 = 3.23 grams
Molar mass of NH3 = 17.03 g/mol
Molar mass of O2 = 32 g/mol
volume of N2 produced = 0.550 L
Temperature = 295 K
Pressure = 1.00 atm
Step 2: The balanced equation:
4NH3 (aq) + 3O2 (g) → 2 N2 (g) + 6H2O (l)
Step 3: Calculate moles of NH3
Moles NH3 = Mass NH3 / Molar Mass NH3
Moles NH3 = 2.15 grams / 17.03 g/mol
Moles NH3 = 0.126 moles
Step 4: Calculate moles of O2
Moles O2 = 3.23 grams / 32 g/mol
Moles O2 = 0.101 moles
Step 5: Calculate the limiting reactant
For 4 moles NH3 consumed, we need 3 moles of O2 to produce, 2 moles of N2 and 6 moles of H2O
NH3 is the limiting reactant. It will completely be consumed ( 0.126 moles).
O2 is in excess, there will be 3/4 * 0.126 = 0.0945 moles consumed
There will remain 0.101 - 0.945 = 0.0065 moles of O2
Step 6: Calculate moles of N2
For 4 moles NH3 consumed, we need 3 moles of O2 to produce, 2 moles of N2 and 6 moles of H2O
For 4 moles NH3 , we'll have 2 moles of N2 produced
For 0.126 moles NH3 consumed, we'll have 0.063 moles of N2 produced.
Step 7: Calculate volume of N2 produced
p*V = n*R*T
⇒ with p = the pressure of the gas = 1.00 atm
⇒ with V = the volume = TO BE DETERMINED
⇒ with n = the number of moles N2 = 0.063 moles
⇒ with R = the gasconstant = 0.08206 L*atm/K*mol
⇒ with T = the temperature = 295
V = (nRT)/p
V = (0.063*0.08206*295)/1
V = 1.525 L = theoretical yield
Step 8: Calculate the % yield
% yield = actual yield / theoretical yield
% yield = (0.550 L / 1.525 L)*100%
% yield = 36.1 %
Ammonia (NH₃) is the limiting reactant
The percent yield is 36%
Stoichiometry
From the question,
We are to determine which reactant is limiting and the percent yield
First we will write the balanced chemical equation for the reaction
4NH₃(aq) + 3O₂(g) → 2N₂(g) + 6H₂O(l)
This means, 4 moles of ammonia reacts with 3 moles of oxygen gas to produce 2 moles of nitrogen gas and 6 moles of water
Now, we will determine the number of moles of each of the reactants present
- For ammonia, NH₃
Mass = 2.15 g
Using the formula,
[tex]Number\ of\ moles = \frac{Mass}{Molar\ mass}[/tex]
Molar mass of ammonia = 17.031 g/mol
∴ Number of moles of ammonia present = [tex]\frac{2.15}{17.031}[/tex]
Number of moles of ammonia present = 0.12624 mole
- For oxygen gas, O₂
Mass = 3.23 g
Molar mass of O₂ = 32.0 g/mol
∴ Number of moles of O₂ present = [tex]\frac{3.23}{32.0}[/tex]
Number of moles of O₂ present = 0.1009375 mole
Since, 4 moles of ammonia is required to react with 3 moles of oxygen gas
Then,
0.12624 mole of ammonia will react with [tex]\frac{0.12624\times 3}{4}[/tex] moles of oxygen gas
[tex]\frac{0.12624\times 3}{4} = 0.09468[/tex]
∴ The 0.12624 mole of ammonia will react with 0.09468 mole out of the 0.1009375 mole of oxygen present
This means oxygen is in excess.
Hence, Ammonia (NH₃) is the limiting reactant
Now, for the percent yield
Percent yield can be calculated using the formula,
[tex]Percent \ yield =\frac{Actual\ yield }{Theoretical \ yield } \times 100\%[/tex]
Now, we will determine the theoretical yield
From the balanced chemical equation,
4 moles of ammonia reacts with 3 moles of oxygen gas to produce 2 moles of nitrogen gas
Then,
The 0.12624 mole of ammonia will react with 0.09468 mole os oxygen gas to produce 0.06312 mole of nitrogen gas
∴ The theoretical yield of nitrogen gas is 0.06312 mole
Now, we determine the actual yield in terms of number of moles
From the given information,
Actual yield in volume = 0.550 L
Temperature = 295 K
Pressure = 1.00 atm
From the ideal gas equation
PV= nRT
Then,
[tex]n = \frac{PV}{RT}[/tex]
[tex]n = \frac{1.00 \times 0.550}{0.08206 \times 295}[/tex]
[tex]n = 0.02272 \ mole[/tex]
This is the actual yield in terms of number of moles
∴ [tex]Percent\ yield = \frac{0.02272}{0.06312} \times 100\%[/tex]
Percent yield = 0.359949 × 100%
Percent yield = 35.9949%
Percent yield ≅ 36%
Hence, the percent yield is 36%
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