The value of K_a for nitrous acid (HNO₂) at 25 °C is given in Appendix D. (c) What is the value of ΔG at equilibrium?

Verified step by step guidance

1. <insert step 1> Identify the relationship between the equilibrium constant (K) and the Gibbs free energy change (ΔG) at equilibrium. The equation is ΔG = -RT ln(K), where R is the universal gas constant and T is the temperature in Kelvin.>
2. <insert step 2> Convert the temperature from Celsius to Kelvin by adding 273.15 to the given temperature in Celsius.>
3. <insert step 3> Use the value of the gas constant R, which is 8.314 J/(mol·K).>
4. <insert step 4> Look up the value of the equilibrium constant K for nitrous acid (HNO2) from Appendix D.>
5. <insert step 5> Substitute the values of R, T, and K into the equation ΔG = -RT ln(K) to find the Gibbs free energy change at equilibrium.>

Key Concepts

Acid Dissociation Constant (K_a)

The acid dissociation constant (K_a) quantifies the strength of an acid in solution. It is defined as the equilibrium constant for the dissociation of an acid into its conjugate base and a proton. A higher K_a value indicates a stronger acid, meaning it dissociates more completely in solution. Understanding K_a is essential for predicting the behavior of acids in chemical reactions.

Gibbs Free Energy (ΔG)

Gibbs free energy (ΔG) is a thermodynamic potential that measures the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure. At equilibrium, ΔG is zero, indicating that the system is in a state of balance and no net change occurs. The relationship between ΔG and K_a can be expressed by the equation ΔG = -RT ln(K_a), linking thermodynamics and chemical equilibrium.

Equilibrium in Chemical Reactions

Equilibrium in chemical reactions refers to the state where the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. At this point, the system has reached a dynamic balance, and the concentrations do not change over time. Understanding equilibrium is crucial for calculating ΔG and interpreting the behavior of acids and bases in solution.