Question Video: Writing the Equilibrium Constant for Concentration Equation for the Reaction between Nitrogen and Hydrogen | Nagwa Question Video: Writing the Equilibrium Constant for Concentration Equation for the Reaction between Nitrogen and Hydrogen | Nagwa

# Question Video: Writing the Equilibrium Constant for Concentration Equation for the Reaction between Nitrogen and Hydrogen Chemistry • Third Year of Secondary School

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The equilibrium of a chemical reaction can be expressed by 𝐾_c, the equilibrium constant for concentration. Find the correct equation for 𝐾_c for the reaction shown between nitrogen and hydrogen: 3H₂ + N₂ ⇌ 2NH₃

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### Video Transcript

The equilibrium of a chemical reaction can be expressed by 𝐾 c, the equilibrium constant for concentration. Find the correct equation for 𝐾 c for the reaction shown between nitrogen and hydrogen. Three H2 plus N2 are in equilibrium with two NH3.

The equilibrium constant for concentration expresses a value related to the ratio between the concentration of the reactants and the concentration of the products at equilibrium.

Let’s consider a generic reaction at equilibrium. In this equation, the lowercase letters represent molar coefficients and the uppercase letters represent chemical formulas. For this general reaction, we could write an equation to calculate the equilibrium constant for concentration. In this equation, the concentration of the products raised to their molar coefficients is divided by the concentration of the reactants raised to their molar coefficients. We can apply the general reaction equation and equilibrium constant for concentration equation to the reaction given in the question.

To write the equation for the equilibrium constant for concentration for the given reaction, we can start by writing the product NH3 in brackets, followed by the exponent two, the molar coefficient which appears in front of NH3 in the chemical equation. We divide this by the concentration of the reactants H2 and N2. Hydrogen has a molar coefficient of three. So the concentration of hydrogen in the equilibrium constant equation is raised to the power of three.

In conclusion, the correct equation for 𝐾 c for the reaction between nitrogen and hydrogen is 𝐾 c equals the concentration of NH3 squared divided by the concentration of H2 cubed times the concentration of N2.

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