Kc=5.85x10^-3 at 25 degrees C for the reaction
N2O4(g)<-->2NO2(g)
fifteen(15.0) grams of N2O4 is confined in a 5.00-L flask at 25 degrees C. Calculate(a) the number of moles of NO2 present at equilibrium and(b) the percentage of the original N2O4 that is dissociated.
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Convert 15.0 g N2O4 to moles and that divided by 5.0 L to obtain molarity.
Set up an ICE chart, substitute into Kc expression and solve.
what does it mean when it says the percentage of the original N2O4 that is dissociated.
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When you finish and know the equilibrium concn of N2O4, then (amt N2O4 present in grams/15.0)*100 = ?? I think you will get the percent answer if you use (moles at equil/original moles)*100 = ??
.sljck
To calculate the number of moles of NO2 present at equilibrium, we can use the ideal gas law and the stoichiometry of the reaction.
(a) To calculate the number of moles of NO2, we need to determine the equilibrium concentration of NO2 using the equilibrium constant (Kc) and the initial concentration of N2O4.
The equation for the reaction is:
N2O4(g) <--> 2NO2(g)
Given:
Kc = 5.85 x 10^-3
Initial mass of N2O4 = 15.0 grams
Volume = 5.00 L
Temperature = 25 degrees C (which is 298 K)
First, we need to convert the mass of N2O4 to moles.
Molar mass of N2O4 = 92.02 g/mol
Moles of N2O4 = (Mass of N2O4) / (Molar mass of N2O4)
Moles of N2O4 = 15.0 g / 92.02 g/mol
Moles of N2O4 = 0.163 mol
Since the stoichiometry of the reaction is 1:2 (N2O4:NO2), the initial concentration of N2O4 is 0.163 mol / 5.00 L = 0.0326 M.
Now, we can use the equilibrium expression to find the concentration of NO2.
Kc = [NO2]^2 / [N2O4]
Let x be the change in concentration of N2O4 and 2x be the change in concentration of NO2.
Using the initial concentration and the changes, we can write:
[N2O4] = 0.0326 - x
[NO2] = 2x
Substituting these values into the equilibrium expression:
Kc = (2x)^2 / (0.0326 - x)
Substitute the value of Kc (5.85 x 10^-3) and solve for x using the quadratic equation or approximation method. This will give the change in concentration of N2O4 and thus the equilibrium concentration of NO2.
(b) To calculate the percentage of the original N2O4 that is dissociated, we need to find the moles of N2O4 that react to form NO2 at equilibrium and compare it to the moles of N2O4 initially present.
Moles of N2O4 dissociated = initial moles of N2O4 - moles of N2O4 at equilibrium
Percentage of N2O4 dissociated = (moles of N2O4 dissociated / initial moles of N2O4) x 100%
Calculate these values to find the percentage of the original N2O4 that is dissociated.