A 0.0583 mol sample of formaldehyde vapour, CH2O, was placed in a heated 0.359 L vessel and some of it decomposed. The reaction is CH2O(g)---> H2(g) + CO(g). At equilibrium, the CH2O concentration was 0.0449 M. What is the value of Kc for this reaction?
my answer was 0.00295 but i don't think that's correct
Why didn't you show what you did so we could check it?
To find the value of Kc for the given reaction, we can use the equilibrium concentrations of the species involved.
According to the balanced equation:
CH2O(g) ---> H2(g) + CO(g)
At equilibrium, the concentration of CH2O is given as 0.0449 M. This implies that [CH2O] = 0.0449 M.
Since the initial volume of the vessel is 0.359 L, we can calculate the initial moles of CH2O using the given moles:
moles of CH2O = 0.0583 mol
Now, we can use the initial moles and the volume to calculate the initial concentration of CH2O:
[CH2O] = moles of CH2O / volume of vessel
[CH2O] = 0.0583 mol / 0.359 L
Therefore, [CH2O] = 0.1624 M.
By doing the same calculations for the products, we find that [H2] = [CO] = 0.0812 M.
Now we can write the expression for Kc, the equilibrium constant:
Kc = [H2] * [CO] / [CH2O]
Substituting the values we calculated earlier:
Kc = (0.0812 M) * (0.0812 M) / (0.1624 M)
Simplifying this expression:
Kc = 0.1644 M² / 0.1624 M
Finally, calculating this division:
Kc = 1.012
Therefore, the value of Kc for this reaction is approximately 1.012.
To find the value of Kc for the given reaction, we need to use the equation:
Kc = ([H2] * [CO]) / [CH2O]
Given that the initial CH2O concentration was 0.0583 mol in a 0.359 L vessel, we can calculate the initial concentration [CH2O]0:
[CH2O]0 = (0.0583 mol) / (0.359 L) = 0.162 M
At equilibrium, the concentration of CH2O is given as 0.0449 M.
Substituting the values into the equation, we get:
Kc = ([H2] * [CO]) / [CH2O] = (x * x) / (0.0449 - x) ---(1)
where x represents the concentration of both H2 and CO at equilibrium.
Since the reaction CH2O(g) --> H2(g) + CO(g) is a 1:1:1 molar ratio, the equilibrium concentrations of H2 and CO will be equal (x).
Substituting x into equation (1):
Kc = (x * x) / (0.0449 - x)
To solve for x, we can use the quadratic equation:
0 = x^2 + Kc * x - Kc * 0.0449
Rearranging and substituting A = 1, B = Kc, and C = - Kc * 0.0449:
x^2 + Kc * x - Kc * 0.0449 = 0
Now, we need to solve this quadratic equation for x. Once we find the value of x, we can substitute it back into equation (1) to calculate the value of Kc.
Please double-check your calculations as your answer of 0.00295 may not be correct.