Chemistry Kc equilibrium question. Please help.
I have been set this multiple choice Q, however all my working doesn't achieve any of the given answers:
'A quantity of HI was heated in a sealed tube until it reached equilibrium. The concentration of HI at equilibrium was 0.0760moldm⁻³.
2HI (g)↔ H₂(g) + I₂(g)
Kc= 54.6 under these conditions.
What are the concentrations, in moldm⁻³, of hydrogen and iodine in the equilibrium mixture?'
A) 1.17 x 10^-3
B) 4.78 x 10^-3
C) 1.85 x 10^-4
D) 9.55 x 10^-3
'A quantity of HI was heated in a sealed tube until it reached equilibrium. The concentration of HI at equilibrium was 0.0760moldm⁻³.
2HI (g)↔ H₂(g) + I₂(g)
Kc= 54.6 under these conditions.
What are the concentrations, in moldm⁻³, of hydrogen and iodine in the equilibrium mixture?'
A) 1.17 x 10^-3
B) 4.78 x 10^-3
C) 1.85 x 10^-4
D) 9.55 x 10^-3
Original post by lordaxil
What have you tried so far?
I have assumed that the concentrations of hydrogen and iodine will be equal as they have a 1:1 ratio and so have subbed them into the Kc equation as 'y', along with the given values of Kc and concentration of HI. Then I solved to find y. It wont let me upload a picture of my workings.
kc= x[i2] / [hi]^2
54.6= [y]x[y] / [0.0760]^2
then solve for y.
(edited 1 month ago)
Original post by Gothic_Moth
I have assumed that the concentrations of hydrogen and iodine will be equal as they have a 1:1 ratio and so have subbed them into the Kc equation as 'y', along with the given values of Kc and concentration of HI. Then I solved to find y. It wont let me upload a picture of my workings.
kc= x[i2] / [hi]^2
54.6= [y]x[y] / [0.0760]^2
then solve for y.
kc= x[i2] / [hi]^2
54.6= [y]x[y] / [0.0760]^2
then solve for y.
Yh this is weird everything I tried doesn't work, I even substituted each value to the kc constant expression and it still doesn't give that constant are you sure the options are right?
The equilibrium equation is written the wrong way around. In this case, Kc = 54.6 is defined with the forward reaction being H2 + I2 ------> 2HI (or you need to use Kc = 1/54.6). Also, the concentration of HI at equilibrium should be 0.0706 mol dm⁻³ (not 0.0760) to get the correct numerical answer. (compare with https://brainly.com/question/20340387)
Original post by lordaxil
The equilibrium equation is written the wrong way around. In this case, Kc = 54.6 is defined with the forward reaction being H2 + I2 ------> 2HI (or you need to use Kc = 1/54.6). Also, the concentration of HI at equilibrium should be 0.0706 mol dm⁻³ (not 0.0760) to get the correct numerical answer. (compare with https://brainly.com/question/20340387)
Thank you! I think my teacher may have made a typo on the google form they sent us then.
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