Consider the following reaction:
2 SO2 (g) + O2 (g)----> 2 SO3 (g)
If 285.3 mL of SO2 is allowed to react with 158.9 mL of O2 (both measured at 315 K and 50.0 mmHg), what is the limiting reactant and theoretical yield of SO3 in moles? If 187.2 mL of SO3 is collected (measured at 315 K and 50.0 mm Hg), what is the percent yield for the reaction?
limiting reactant:
theoretical yield:
percent yield:
I am having troubles starting this problem, anyone know where to begin? I know we need to get from SO2 to SO3 and likewise O2 to SO3 but starting out with Ml I am not sure how to get a molar mass.
Use PV = nRT, substitute for P, V, R, and T, and solve for n = mols. Go from there.
I tried doing it that way already but it just doesn't look correct, because I set up PV=nRT to n=PV/RT. Entering the numbers I would get
((0.0658 atm)(0.2853))/((0.08206 L*atm/K*mol)(315K)) and I would get 0.000726 moles. After that would I just go straight to the number of moles of SO2 and SO3 so set up like so: 0.000726 mol SO2* 2 mol SO3/ 2 mol SO2* 80.07 g/ 1 mol SO3 ?
7.26E-4 is correct for moles SO2.
And your next step is ok but you don't need to go all the way to grams (yet).
7.26E-4 x (2 moles SO3/2 moles SO2) = 7.26E-4 mols SO3 (if all of the SO2 reacts).
Now do the same thing with oxygen, see how many moles oxygen you have initially, and convert that to moles SO3.
Those two numbers you get for moles SO3 probably will not be the same which means one of them is wrong. The correct value in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting reagent. Use that smaller value, convert that to grams SO3, and that is the theoretical yield.
Now you have the limiting reagent.
Now you have the theoretical yield.
Now yu can calculate the percent yield if you obtain the amount given in the problem.
Okay I believe I got it, thank you so much for the help! :)
You're very welcome. Come again. Thank you for showing your work It helps us diagnose the problem.
Well, it seems like you've stumbled upon a bit of a chemical conundrum. Allow me, Clown Bot, to assist you in untangling this molecular mess!
First things first, to determine the limiting reactant, we need to convert the volumes of SO2 and O2 into moles. To do this, we have to use the ideal gas law equation:
PV = nRT
Where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature in Kelvin.
But wait, do you know why chemists like nuns? Because they have free "molar" habits! Okay, enough with the puns. Let's get down to business!
We'll start by converting the volumes using the ideal gas law equation. But to do that effectively, we need the molar masses of SO2, O2, and SO3. SO, let me give them to you:
Molar mass of SO2 = 64.06 g/mol
Molar mass of O2 = 32.00 g/mol
Molar mass of SO3 = 80.06 g/mol
Now we can convert the volumes to moles:
Moles of SO2 = (285.3 mL * 1 L/1000 mL) * (50.0 mmHg/760 mmHg) * (1 mol/22.4 L) * (64.06 g/1 mol)
Moles of O2 = (158.9 mL * 1 L/1000 mL) * (50.0 mmHg/760 mmHg) * (1 mol/22.4 L) * (32.00 g/1 mol)
Now that we have the moles of the reactants, we can determine the limiting reactant. The one that produces the least amount of product is the limiting reactant.
To do a little math magic, divide the moles of each reactant by their stoichiometric coefficients from the balanced equation (2 for SO2 and 1 for O2). The one with the smaller number is the limiting reactant!
But hey, I'm no math magician, so I'll let you perform this trick. Let me know which reactant ends up being the limiting reactant.
Once you've discovered the limiting reactant, you can use stoichiometry to determine the theoretical yield of SO3 in moles. Again, this involves a little math, but I believe in you!
Calculate the moles of SO3 using the limiting reactant. Remember, the stoichiometry from the balanced equation tells us that 2 moles of SO2 produce 2 moles of SO3.
Now, to find the percent yield, you'll need to compare the actual yield (given as 187.2 mL) to the theoretical yield (calculated earlier in moles). Percent yield is calculated by dividing the actual yield by the theoretical yield and multiplying by 100.
So go ahead, perform these calculations, and let me know the answers! I'll be here, trying to resist the urge to juggle beakers.
To solve this problem, we need to determine the limiting reactant and theoretical yield of SO3 in moles. Then, we can use the given volume of collected SO3 to calculate the percent yield.
1. Convert the given volumes of gases (SO2, O2, and SO3) to moles:
To convert the volumes to moles, we need to use the ideal gas law equation:
PV = nRT
Where:
P = pressure in atm (convert mmHg to atm)
V = volume in liters (convert mL to liters)
n = number of moles
R = ideal gas constant (0.0821 L.atm/mol.K)
T = temperature in Kelvin.
Given:
SO2 volume = 285.3 mL = 0.2853 L
O2 volume = 158.9 mL = 0.1589 L
SO3 volume = 187.2 mL = 0.1872 L
Pressure (P) = 50.0 mmHg = (50.0/760) atm (approx. 0.0658 atm)
Temperature (T) = 315 K
For SO2:
n(SO2) = (P * V) / (R * T) = (0.0658 atm * 0.2853 L) / (0.0821 L.atm/mol.K * 315 K)
For O2:
n(O2) = (P * V) / (R * T) = (0.0658 atm * 0.1589 L) / (0.0821 L.atm/mol.K * 315 K)
2. Calculate the moles ratio of SO2 to O2 using the balanced equation:
The balanced equation is: 2 SO2 (g) + O2 (g) → 2 SO3 (g)
The ratio of SO2 to O2 in the balanced equation is 2:1, as 2 moles of SO2 react with 1 mole of O2.
3. Determine the limiting reactant:
Find the limiting reactant by comparing the moles of SO2 and O2 calculated in step 1. The reactant that produces a smaller amount of product is the limiting reactant.
4. Calculate the theoretical yield:
Now, calculate the theoretical yield of SO3 by using the limiting reactant found in step 3. The molar ratio between the limiting reactant and SO3 is 2:2 (or 1:1).
For example, if SO2 is the limiting reactant:
n(SO3) = n(SO2) * (2 moles SO3 / 2 moles SO2)
5. Calculate the percent yield:
Finally, to calculate the percent yield, divide the actual yield (given as volume of collected SO3) by the theoretical yield calculated in step 4 and multiply by 100.
Now that we know the approach, you can calculate the limiting reactant, theoretical yield, and percent yield by following these steps.