I posted a question similar to this one a few days ago and someone helped me with it. but now im on a similar one and i did the same thing to find the answer but it was wrong. what am i doing wrong?
An equilibrium mixture of the following reaction was found to have [CH4] = 0.0203 M and [C2H2] = 0.0451 M at 1700°C. What is the concentration of H2?
2 CH4(g) <-> C2H2(g) + 3 H2(g)
Keq = 0.154 at 1700°C
i got: .518
what am i doing wrong?
You didn't show your work so I can't tell you what you did wrong.
Keq = (C2H2)(H2)^3/(CH4)^2
0.154 = (0.0451)(H2)^3/(0.0203)^2
(H2) = 0.112 M
you didn't show work either you noob!
To determine what might have gone wrong in your calculation, let's go through the steps for solving this equilibrium concentration problem.
1. Start with the given equilibrium concentrations for CH4 and C2H2: [CH4] = 0.0203 M and [C2H2] = 0.0451 M. These initial concentrations are crucial for solving this problem.
2. Since we are interested in finding the concentration of H2, let's assign "x" as the initial concentration of H2. Since it's unknown, we can represent it as [H2] = x M.
3. Next, apply the stoichiometry of the balanced chemical equation to determine the concentration changes of each substance in the reaction. According to the balanced equation, for every 2 moles of CH4 that react, 3 moles of H2 are produced. Therefore, [H2] at equilibrium = x + (3 * 0.0203) = x + 0.0609 M.
4. Now, plug the equilibrium concentrations into the equilibrium constant expression and solve for x:
Keq = [C2H2] * [H2]^3 / [CH4]^2
0.154 = 0.0451 * (x + 0.0609)^3 / (0.0203)^2
Simplifying the equation further, we have:
0.154 = 0.0451 * (x + 0.0609)^3 / 0.00041209
0.00041209 * 0.154 = 0.0451 * (x + 0.0609)^3
0.0000633966 = (x + 0.0609)^3
5. Take the cube root of both sides to solve for (x + 0.0609):
x + 0.0609 = ∛(0.0000633966)
x + 0.0609 = 0.040
x = 0.040 - 0.0609
x = -0.0209 M
Oops! It seems that we encountered a negative concentration value for H2, which is not physically possible in this context. Therefore, there might be an error in your calculation or initial assumption.
Double-check your calculations to ensure that you have applied the stoichiometry correctly and that you have correctly solved the equilibrium constant expression. Sometimes, rounding errors or calculation errors can lead to incorrect answers. Make sure you are using accurate values throughout the process.
If you continue to face difficulties, it's helpful to seek assistance from a teacher, tutor, or classmates who can review your work and identify any mistakes. They can provide personalized guidance based on a direct assessment of your calculations.