Question

A sample of NH4HS(s) is placed in a 2.61 −L flask containing 0.120 mol NH3(g).

NH4HS(s)⇌NH3(g)+H2S(g) KP=0.108 at 25∘C

What will be the total gas pressure when equilibrium is established at 25∘C?
Express your answer using four significant figures.

I've done

PV=nRT
P= nRT/V
P= (0.120mol)(0.08206 L.atm/K.mol)(25+273K) / (2.61L)

NH4HS(s)⇌NH3(g)+H2S(g)
I - 1.124 0
C - +x +x
E - 1.124+x x

0.108= x(1.124+x)

x^2 +1.124x-0.108=0

x1 = 0.08903 x2= -1.2136

P total gas = 0.08903 + 1.124 = 1.2130

Did I do something wrong? Any help would be greatly appreciated. Thx

Answer 1

answer to four sig digits. Wondering what to four sig digits for 273 in temp will change. I dont see any other red flags.

Answer 2

First off you made a math error.
x = 0.08903. Right. But you added that in once and not twice.
Total P = 1.124 + 0.08903 + 0.08903 = 1.302 using T as 298. Using T as 298.15 may change that last place but I didn't go through the math.

Answer 3

Another point you may check is Kp. Is that Kp or Kc. You don't have it in the problem you posted anywhere that I can see. Also, read your problem and check that you copied the number correctly.