3 moles of H_2 and 4 moles of I_2 were heated in a sealed tube at a given temperature at which Kc is 50. If the volume of the tube is 1 dm^3 , determine the composition of the equilibrium.
H_2 + I_2 ⇌ 2HI
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OpenStudy (anonymous):
help plzz!! its been 3 hours !!
OpenStudy (jfraser):
what's the form for the equilibrium expression for this reaction?
OpenStudy (anonymous):
product over reactants
OpenStudy (jfraser):
what about the equation? K = ?? for this reaction?
OpenStudy (anonymous):
i just need help on the table !! rest i can do
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OpenStudy (anonymous):
K=50
OpenStudy (jfraser):
what's the equation for K for this reaction?
OpenStudy (anonymous):
\[Kc=\frac{ [HI]^2 }{ [H_2][I_2] }\]
OpenStudy (jfraser):
that's the one
OpenStudy (jfraser):
You know you start with 3 moles of H2 and 4 moles of I2, and you know the equilibrium value has to be 50, so plug into the equation for Kc and solve for the equilibrium concentrations
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OpenStudy (anonymous):
so could u help me in the table ?
OpenStudy (anonymous):
H2 + I2 --> 2HI
Moles at initial state = 3 4 0
OpenStudy (anonymous):
Moles at equilibrium state ??
OpenStudy (jfraser):
R \(H_2 + I_2 \rightleftharpoons 2HI\)
I 3M 4M "0"
C "-x" "-x" "+2x"
E
what are the equilibrium values going to be?
OpenStudy (anonymous):
thats what i need to know
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OpenStudy (anonymous):
ok i'll try
OpenStudy (anonymous):
H2 + I2 --> 2HI
moles at e = 3-x 4-x 7-x
OpenStudy (anonymous):
is this correct ? coz i m not sure about this
OpenStudy (anonymous):
what happened ??
OpenStudy (anonymous):
hello u there ?
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OpenStudy (jfraser):
the equilibrium concentration of HI is 2x, since you start with nothing, and gain twice the amount that the H2 loses.
Look at the coefficients of the balanced reaction
OpenStudy (anonymous):
u mean 7-2x
OpenStudy (jfraser):
no, i mean 2x
OpenStudy (jfraser):
where does the 7 come from? from adding the H2 and I2 together? why would you do that?
OpenStudy (anonymous):
oh i was mistaken
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OpenStudy (anonymous):
so this is the equation
OpenStudy (anonymous):
\[Kc=\frac{ [2x]^2 }{ [3-x][4-x] }\]
OpenStudy (jfraser):
yes, and the whole value of Kc is 50.
OpenStudy (jfraser):
so solve for X, and you'll get the equilibrium concentrations
OpenStudy (anonymous):
for all 3 ?
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OpenStudy (jfraser):
solve for x, then plug each x back into the equilibrium concentration of each species
OpenStudy (anonymous):
oh yes ..i remember !! thanks
OpenStudy (jfraser):
yw
OpenStudy (anonymous):
x^2-35x+600=0
OpenStudy (anonymous):
sorry it is
46x^2-350x+600=0
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OpenStudy (jfraser):
then solve for x
OpenStudy (anonymous):
which value should i use for eq. conc. x=5 or x=60/23 ??
OpenStudy (jfraser):
can the equilibrium concentration of H2 be LARGER thanthe amount of H2 you start with?
OpenStudy (anonymous):
no
OpenStudy (anonymous):
x=60/23 ? right ?
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OpenStudy (jfraser):
so which solution for x is the only one that makes sense?
OpenStudy (anonymous):
x=60/23
OpenStudy (jfraser):
right, now find the equilibrium concentration of H2
OpenStudy (anonymous):
0.391
OpenStudy (jfraser):
and the concentrations of the rest of the reaction
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OpenStudy (anonymous):
I2 = 1.391
OpenStudy (anonymous):
and 2HI = 5.217
OpenStudy (jfraser):
look right to me. to check, plug those values into K and make sure you get 50