I really need help here guys!!!!
Here is the question:
For the following reaction
Kc = 255 at 1000 K
CO(g) + Cl
2(g)
COCl
2 (g)
A reaction mixture initially contains a CO concentration of 0.1490 M and a Cl
2 concentration of 0.174 M at 1000 K.
What is the equilibrium concentration of CO at 1000 ?
What is the equilibrium concentration of Cl
2 at 1000 ?
What is the equilibrium concentration of COCl
2 at 1000 ?
ok. ive tried this prob a number of times and even asked some people in my class and everyone comes up with the same number. and its wrong. i know you guys here can figure out what i am doing wrong....
CO(g) + Cl
2(g)
COCl
2 (g)
I: .1490M .174M 0
C: -x -x +x
E: .1490 - x .174-x x
---------------------------------------------------------------
x/(.1490-x)(.174-x) = 255
x/255(.0259 -.323x+x
2)
6.60-82.4x+255x
2 = x
6.60-83.4x+255x
2 = 0
through the quadratic equation, i get
x= .193 or x= .134
since x cannot be greater than the original concentration, i picked .134
Substituting back in for x,
.1490-.134 = .0150
sig figs aside, i put the following answers in and they were all wrong:
5.00×10−3
1.50×10−2
1.50×10−2
1.40×10−2 Not quite. Check through your calculations; you may have made a rounding error or used the wrong number of significant figures.
1.50×10−2
so, could it be .013? note the message that came up when i tried .014. i tried the equation in about 5 or 6 different quadratic equation solvers and got .134 on all of them except for one, where i got .133. when i substitute back in with .133, i get .016 as an answer. i havent attempted .016 as an answer, but the message leads me to believe its closer to .014 than .016. and i only have one attempt left, so i, er, have to be right. Oh, and when i did the quadratic by hand, i came out with .015. can anyone tell me what i am doing wrong? i would really hate to get this wrong due to a rounding error, but i am certain that i have the concept correct. any info at all is much appreciated. esp if i am messing up my sig figs.