At 25 deg C, Kc is 5.84x10-3 for the dissociation of dinitrogen tetraoxide to nitrogen dioxide.
N2O4(g) ==== 2NO2(g)
a) Calculate the equilibrium concentration of both gases when 4.00 grams of N2O4 is placed at 2.00-liter flask at 25 deg C.
b) What will be the new equilibrium concentrations if the volume of the system is suddenly increased to 3.00-liters at 25 deg C?
c) What will be the new equilibrium concentrations if the volume is decreased to 1.00-liter at 25 deg C?
mols N2O4 = 4/molar mass = 4/92 = about 0.0435M
M N2O4 = 0.0435/2 = about 0.0217M
..........N2O4 ==> 2NO2
I.........0.0217.....0
C.........-x........2x
E.......0.0217-x....2x
Substitute the E line into Kc expression and solve for x and 0.0217-x
b and c are done the same way.
Post your work if you get stuck.
To solve this problem, we need to use the given equilibrium constant (Kc) and the stoichiometry of the balanced chemical equation.
a) Calculate the equilibrium concentration of both gases when 4.00 grams of N2O4 is placed in a 2.00-liter flask at 25 deg C.
Step 1: Convert the mass of N2O4 to moles.
To do this, we need the molar mass of N2O4. The molar mass of N2O4 is calculated by adding the atomic masses of nitrogen (N) and oxygen (O) in the compound.
Molar mass of N2O4 = (2 * molar mass of N) + (4 * molar mass of O) = (2 * 14.01 g/mol) + (4 * 16.00 g/mol) = 92.02 g/mol
Number of moles of N2O4 = mass / molar mass = 4.00 g / 92.02 g/mol
Step 2: Calculate the initial concentration of N2O4 in moles per liter.
Concentration (moles per liter) = moles / volume (in liters) = (4.00 g / 92.02 g/mol) / 2.00 L
Step 3: Use the stoichiometry of the balanced equation to calculate the initial concentration of NO2.
According to the balanced equation, the ratio of N2O4 to NO2 is 1:2.
So, the initial concentration of NO2 in moles per liter is double that of N2O4.
b) What will be the new equilibrium concentrations if the volume of the system is suddenly increased to 3.00 liters at 25 deg C?
If the volume of the system is suddenly increased, the concentrations of both N2O4 and NO2 will decrease. To calculate the new concentrations, we need to use the initial concentrations from part (a) and apply the following formula:
New concentration = Initial concentration * (Initial volume / New volume)
In this case, the new volume is 3.00 liters.
c) What will be the new equilibrium concentrations if the volume is decreased to 1.00 liter at 25 deg C?
If the volume is decreased, the concentrations of both N2O4 and NO2 will increase. Again, we use the same formula as in part (b):
New concentration = Initial concentration * (Initial volume / New volume)
This time, the new volume is 1.00 liter.