Question

Consider the reaction H₂ (g) + I₂ (g) ‡„ 2 HI (g), which has a Kp of 50.5 at a certain temperature. A reaction mixture initially contains 0.500 atm of H₂, 0.500 atm of I₂, and 0.850 atm of HI. What is the partial pressure of H₂ when the reaction reaches equilibrium?

Answer 1

To find the equilibrium partial pressure of ‎H‎2 in the given reaction, an ICE table is employed to express the changes in partial pressures, and the equilibrium constant expression is applied to determine the changes required to achieve equilibrium.

Step-by-step explanation:

The student asked about a chemical equilibrium problem involving the reaction H2(g) + I2(g) ⇌ 2 HI(g). The reaction has an equilibrium constant, Kp of 50.5 at a specific temperature. Initially, the reaction mixture contains 0.500 atm H2, 0.500 atm I2, and 0.850 atm HI. To find the partial pressure of H2 at equilibrium, we set up an ICE table (Initial, Change, Equilibrium) and apply the equilibrium constant.

Let x be the change in partial pressure of H2 from its initial value of 0.500 atm as it reacts. At equilibrium, the partial pressures would be:

• H2: 0.500 - x atm
• I2: 0.500 - x atm
• HI: 0.850 + 2x atm

To calculate the equilibrium partial pressures, we use the equation for the reaction quotient Qp,

Qp = (PHI)2 / (PH2)(PI2), which at equilibrium is equal to Kp. After substituting the partial pressures in terms of x and solving for x using the quadratic formula (if necessary), we can find the equilibrium value for the partial pressure of H2.