(a) At 800 K the equilibrium constant for I2(g) 2 I(g) is Kc = 3.1 10-5. If an equilibrium mixture in a 10.0-L vessel contains 3.25 10-2 g of I(g), how many grams of I2 are in the mixture?
(b) For 2 SO2(g) + O2(g) 2 SO3(g), Kp = 3.0 104 at 700 K. In a 2.00-L vessel the equilibrium mixture contains 1.46 g of SO3 and 0.130 g of O2. How many grams of SO2 are in the vessel?
how do you do these?
Didn't know that you were answering it.
Note that in a you must convert to M as I did.
Note that in b you do not need to convert to M because part b is Kp and not Kc. Pressure is what you want in part b and molarity won't do it unless you wish to use molarity to find pressure.
Kp=is pressure, I apologize about that one. So, you have to use the setup that DrBob222 gave you in his initial post.
To solve these equilibrium problems, we can use the concept of stoichiometry and the equilibrium constant (Kc or Kp) to find the quantities of reactants and products.
(a) To find the number of grams of I2 in the mixture, we need to use the amount of I(g) given and the equilibrium constant.
Step 1: Convert the given mass of I(g) to moles.
- Calculate the molar mass of I:
Molar mass of I(g) = 126.90 g/mol
- Use the equation: moles = mass / molar mass
Moles of I(g) = (3.25 x 10^-2 g) / (126.90 g/mol)
Step 2: Use the stoichiometry of the balanced equation to determine the moles of I2.
- From the balanced equation: I2(g) 2 I(g)
Moles of I2 = (moles of I(g)) / 2
Step 3: Calculate the concentration of I2 using the equilibrium constant.
- Use the equation: Kc = [I(g)]^2 / [I2(g)]
Rearrange the equation: [I2(g)] = [I(g)]^2 / Kc
[I2(g)] = (moles of I2) / (volume of vessel in liters)
Step 4: Convert the calculated moles of I2 to grams.
- Calculate the mass using the equation: mass = moles x molar mass
Mass of I2 = (moles of I2) x (molar mass of I2)
(b) To find the number of grams of SO2 in the vessel, we can follow a similar procedure using the given amounts and the equilibrium constant.
Step 1: Convert the given masses of SO3 and O2 to moles.
- Calculate the molar masses of SO3 and O2:
Molar mass of SO3 = 80.06 g/mol
Molar mass of O2 = 32.00 g/mol
- Use the equations: moles = mass / molar mass
Moles of SO3 = (1.46 g) / (80.06 g/mol)
Moles of O2 = (0.130 g) / (32.00 g/mol)
Step 2: Use the stoichiometry of the balanced equation to determine the moles of SO2.
- From the balanced equation: 2 SO2(g) + O2(g) 2 SO3(g)
Moles of SO2 = 2 x (moles of SO3)
Step 3: Calculate the concentration of SO2 using the equilibrium constant.
- Use the equation: Kp = (P(SO2))^2 x P(O2) / (P(SO3))^2
Rearrange the equation to solve for P(SO2):
P(SO2) = sqrt((Kp x (P(SO3))^2) / P(O2))
P(SO2) = (moles of SO2 x R x T) / (volume of vessel in liters)
Step 4: Convert the calculated moles of SO2 to grams.
- Calculate the mass using the equation: mass = moles x molar mass
Mass of SO2 = (moles of SO2) x (molar mass of SO2)
Note: In these calculations, R is the ideal gas constant (0.0821 L·atm/mol·K), and T is the temperature in Kelvin.
3.25E-2/10L = 2.56E-4 mol and
2.56E-4/10 = 2.56E-5 M
........I2 ==> 2I
E.......?......2.56E-5M
Kc = (I)^2/(I2)
You know Kc and I, solve for I2 in molarity, then convert to grams in the 10 L container.
1.46/80 = about 0.01825 mols SO3.
0.130/32 = about 0.0041 mols O2.
............2SO2 + O2 ==> 2SO3
Why can't you use PV = nRT to solve for pSO2 and again for pO2. Substitute these numbers in Kp expression and solve for pSO2. Finally, use PV = nRT and convert pSO2 to n and to grams. Post your work if you get stuck.
A.)
You have to convert the concentrations to molarity
3.25 x10^-2 g/126.9g*mol-1=moles of I
moles of I/10L=molarity
I2(g)---->2I(g)
I2=[x]
2I=(moles of I2/10L)^2
Since Kc =3.1 x10^-5=products/reactants,
Kc=3.1 x10^-5=(moles of 2I/10L)^2/[x]
Solve for x
to get grams of I2,
Molarity*10L=moles of I2
moles of I2*253.8g*mol-1= g of I2
B.)
2SO2(g)----> O2(g) + 2SO3(g)
You have to convert everything to molarity. I showed you how to do this in A, and you have to find the molecular weights of the compounds in question.
Kp = 3.0 x 10^4 =products/reactants=(SO3)^2(O2)/[2x]^2
solve for x
Multiply x by 2 to get molarity of SO2 and use the same setup that I gave you in A to get grams of SO2