Question Detail

CHM 101 CHM 101 Past Questions Objective Question
Take CBT

Question

A quantity of HI was sealed in a tube, heated to 425 °C and held at this temperature until equilibrium was reached. The concentration of HI in the tube at equilibrium was found to be 0.0706 mol/dm³. Calculate the equilibrium concentration of H₂ (and I₂). For the gas-phase reaction: H₂ + I₂ ⇌ 2HI; Keq = 54.6 at 425 °C
Options
A 9.55 x 10⁻³ M
Correct Answer
B 1.17 x 10⁻³ M
C 1.85 x 10⁻⁴ M
D 4.78 x 10⁻³ M
Correct Answer

Option A is the correct answer.

Detailed Explanation

For H₂ + I₂ ⇌ 2HI, if starting with only HI, let x = [H₂] at equilibrium = [I₂]. Then [HI] = 0.0706 M. Keq = [HI]²/([H₂][I₂]) = (0.0706)² / x² = 54.6. So x² = (0.0706)²/54.6 = 0.004984/54.6 = 9.13×10⁻⁵. x = 9.55×10⁻³ M.

Hint

Use the equilibrium expression and solve for the unknown concentration.

Question Info

Course: CHM 101
Topic: CHM 101 Past Questions
Type: Objective
Difficulty: Not specified
Question 1708 of 1872
Previous Course Details Next