Answer:
Explanation:
<u>1. Equilibrium equation</u>
<u>2. Equilibrium constant</u>
The liquid substances do not appear in the expression of the equilibrium constant.
![k_c=\dfrac{[HBr(g)]^2}{[H_2]}=4.8\times 10^8M](https://tex.z-dn.net/?f=k_c%3D%5Cdfrac%7B%5BHBr%28g%29%5D%5E2%7D%7B%5BH_2%5D%7D%3D4.8%5Ctimes%2010%5E8M)
<u>3. ICE table.</u>
Write the initial, change, equilibrium table:
Molar concentrations:
H₂(g) + Br₂(l) ⇄ 2HBr(g)
I 0.400 0
C - x +2x
E 0.400 - x 2x
<u>4. Substitute into the expression of the equilibrium constant</u>

<u>5. Solve the quadratic equation</u>
- 192,000,000 - 480,000,000x = 4x²
- x² + 120,000,000x - 48,000,000 = 0
Use the quadratic formula:

The only valid solution is x = 0.39999999851M
Thus, the final concentration of H₂(g) is 0.400 - 0.39999999851 ≈ 0.00000000149 ≈ 1.5 × 10⁻⁹M