Question

Problem PageQuestion Nitric acid and nitrogen monoxide react to form nitrogen dioxide and water, like this: (aq)(g)(g)(l) At a certain temperature, a chemist finds that a reaction vessel containing a mixture of nitric acid, nitrogen monoxide, nitrogen dioxide, and water at equilibrium has the following composition: compound amount Calculate the value of the equilibrium constant for this reaction. Round your answer to significant digits. Clears your work. Undoes your last action. Provides information about entering answers.

Answer 1

3.4

Step-by-step explanation:

Nitric acid and nitrogen monoxide react to form nitrogen dioxide and water, like this: 2 HNO₃(aq) + NO(g) ⇄ 3 NO₂(g) + H₂O(l)

At a certain temperature, a chemist finds that a 9.5L reaction vessel containing a mixture of nitric acid, nitrogen monoxide, nitrogen dioxide, and water at equilibrium has the following composition:

compound amount

HNO₃ 15.5g

NO 16.6g

NO₂ 22.5g

H₂O 189.0g

Calculate the value of the equilibrium constant Kc for this reaction. Round your answer to 2 significant digits.

Step 1: Write the balanced equation.

2 HNO₃(aq) + NO(g) ⇄ 3 NO₂(g) + H₂O(l)

Step 2: Calculate the molar concentration of the species at equilibrium

We will use the following expression.

M = mass of solute / molar mass of solute × liters of solution

[HNO₃] = 15.5g / 63.01 g/mol × 9.5 L = 0.026 M

[NO] = 16.6g / 30.01 g/mol × 9.5 L = 0.058 M

[NO₂] = 22.5g / 46.01 g/mol × 9.5 L = 0.051 M

We do not calculate the molarity of water because it is a pure liquid and will not be included in the equilibrium constant.

Step 3: Calculate the equilibrium constant (Kc)

Kc = [NO₂]³/[HNO₃]²×[NO]

Kc = 0.051³/0.026²×0.058

Kc = 3.4