1. At 298 K, bar of H2 gas is placed in a 1.00 L vessel that also contains a lar

Question

1. At 298 K, bar of H2 gas is placed in a 1.00 L vessel that also contains a large excess of I2 solid (and some I2 vapor). Under these conditions, the partial pressure of I2 vapor is fixed. A chemical reaction occurs and HI gas is produced, all at 298 K. a) Write a balanced chemical reaction. Calculate for this reaction. (The problem will be easier if you use I2(s) in your chemical reaction.) b) Find an equation that relates the partial pressure of H2 gas to the partial pressure of HI gas. c) What is the partial pressure of HI gas at equilibrium? d) Use the Gibbs phase rule to calculate F for this system

Explanation / Answer

a)

Balanced reaction

H2(g) + I2(s) = 2HI(g)

dG = Gproducts - Greactants = 2HI - (H2 + I2) = 2*26.5 - 0 = 53 kJ/mol

b)

find equation of H2:

K = P-HI^2 / (P-H2)

dG = -RT*ln(K)

K = exp(-dG/(RT))

K = exp(-53000/(8.314*298)) = 5.124*10^-10

c)

H2 = 1 bar

HI = 0

in equilbirium

H2 = 1-x

HI = 2x

K = P-HI^2 / (P-H2)

5.124*10^-10 =(2X)^2 / (1-x)

4x^2 = 5.124*10^-10 - 5.124*10^-10x

4x^2 +5.124*10^-10x -5.124*10^-10 = 0

x = 1.13*10^-5

H2 = 1-1.13*10^-5 = 0.9999887

HI = 2*1.13*10^-5 = 0.0000226

d)

F = c-P + 2

compounds = 2

phases = 2

then

F = 2-2+2 = 2

we need to set 2 variables, i.e. Temperature and Pressure will be enough

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.