## How do you write an equilibrium expression for Ka?

There is a relationship between the concentration of products and reactants and the dissociation constant (Ka or Kb). For acids, this relationship is shown by the expression: Ka = [H3O+][A-] / [HA].

What is the equilibrium constant expression Ka?

The ratio of the rate constants for the forward and reverse reactions at equilibrium is the equilibrium constant (K), a unitless quantity. The ratio is called the equilibrium constant expression. When a reaction is written in the reverse direction, K and the equilibrium constant expression are inverted.

### How do you calculate K for gas?

Relating Gas Equilibrium Constants to Equilibrium (K) As we have seen above, Kp = Kc (RT)Δn,we can derive this formula from the Ideal Gas Law. We know that Kc is in terms Molarity (MolesLiters), and we can also arrange the Ideal Gas Law (PV = nRT) as: (nL)=(PRT).

What is the general formula for equilibrium expressions?

The equilibrium expression can be manipulated and combined in the following ways: If the reaction is written in reverse, Q becomes Q–1; If the coefficients of an equation are multiplied by n, Q becomes Qn; Q for the sum of two reactions (that is, for two reactions that take place in sequence) is the product (Q1)(Q2).

#### Which is the correct equilibrium constant expression?

Correct answer: The equilibrium expression is defined as the ratio of the concentration of products divided by the concentration of the reactants. Each reactant or product is raised to the power corresponding to its coefficient in the balanced chemical equation.

How do you calculate Ka?

Chemists determine the strength of an acid (Ka) by measuring the concentrations of HA, H 30 + and A – at equilibrium and dividing the concentrations of the products by the concentration of the original acid. Because the concentration of water is a constant, they leave it out of the equation. Ka = [H 3O +] [A -]/[HA]

## Why are Ka values all small numbers?

Almost all Ka values in general are smaller numbers. The reason is that K values represent very weak acids.

How do you write equilibrium constant expression?

The equilibrium constant expression is written as: Kc = [Cu 2+] / [Ag +] 2. Note the solid copper and silver were omitted from the expression. Also, note the coefficient for the silver ion becomes an exponent in the equilibrium constant calculation.

### What is the equation for Ka?

The numerical value of Ka is used to predict the extent of acid dissociation. A large Ka value indicates a stronger acid (more of the acid dissociates) and small Ka value indicates a weaker acid (less of the acid dissociates). For a chemical equation of the form HA + H2O ⇋ H3O + + A −