10 Points Best Answer Chemistry Help?

Ok, I know I just asked a question about chemistry help. But I didn't realize that I had this question also. I'm just really confused about the whole equilibrium process and how to solve it. (My teacher is horrible). Could you explain how you got the answer and the steps you took to get there. Thanks so much! (Best answer = 10 points!)

Given the equilibrium:

2 A2(g) --> B(g)+ C (g)

the equilibrium concentrations of A2(g), B(g) and C(g) were found to be 0.62M; 0.79M and 0.79M. An additional amount of A2 was added to the flask such that the concentration of A2(g) rose to 2.67M, then equilibrium was re-established. Calculate the new equilibrium concentration of B(g). Enter the result with 3 significant figures.

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  • 1 decade ago
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    2 A2 (g) ----> B (g)+ C (g)

    Equilibrium Constant = [ B ] x [ C ] / [ A2 ]^2

    At the first Equilibrium

    Equilibrium Constant

    = [ 0.79 ] x [ 0.79 ] / [ 0.62 x 0.62]

    = 1.6235691

    After addition of A2 [ such that the concentration of A2(g) rose to 2.67M ] and Equilibrium re-established . . . .

    If concentration of B change to 0.79 + d

    Concentration of C will also change to 0.79 + d

    Concentration of A2 will change to 2.67 - 2d

    At the Second Equilibrium

    Equilibrium Constant

    = [ 0.79 = d ] x [ 0.79 + d ] / [ ( 2.67 - 2d ) x ( 2.67 - 2d ) ]

    1.6235691 = [ 0.79 = d ] x [ 0.79 + d ] / [ ( 2.67 - 2d ) x ( 2.67 - 2d ) ]

    d = 0.736136

    Concentration of B ( at new equilibrium ) = 0.79 + 0.736136

    = 1.526136 M

    Your answer should be

    Concentration of B ( at new equilibrium ) = 1.53 M

    Note :

    Don't just blame your teacher . If you carefully read your book ( to understand chemical equilibrium and related principles ) , carefully read the question , use some common senses >> you will be able to do it by yourself .

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  • Anonymous
    1 decade ago

    It appears to me that there are some issues with the question. "2 A2(g) --> B(g)+ C (g)" Is this equation suppose to be balanced? Also the way its written "2 A2" makes it look like A is becoming B and C rather than just breaking into B and C which is a very fundamental problem.

    I'm going to say the best I can do is guess so if someone else could back up my work as right or wrong that would help

    Take the [concentration] of products over reactants = [B][C]/[A2]^2

    plug in the numbers and set that equal to [B][C]/[A2]^2 with the new numbers.

    .79^2/.62^2 = 1.6235

    1.6235 = X^2/2.67^2 --> x^2 = (1.6235)(2.67^2) --> x = 3.40 M B

    Hope that helps, I skipped some math steps as implied.

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