SAAT Chemistry Section 5 (Rates of Chemical Reactions and Chemical Equilibrium) - تحصيلي

Reaction rate

The change of concentration of a reactant or product per unit of time

Average rate formula

△concentration/△t mol(Ls)

Collision theory

States that atoms, ions, and molecules must collide in order to react

Activation energy (E_a)

The minimum amount of energy that reacting particles must have to form the activating complex and lead to a reaction

Activated complex (also known as a transition state)

A temporary, unstable arrangement of atoms in which old bonds are breaking and new bonds are forming

When the speed of a reaction increases

Concentration, temperature, surface area of reactants are all increased and with the presence of a catalyst

Catalyst

A substance that increases the rate of a chemical reaction without being consumed in the reaction

Inhibitor

A substance that slows down reaction rates, or inhibits reactions (some prevent a reaction from happening at all)

Reation rate law

The relationship between the rate of a chemical reaction and the concentration of reactants at a given temperature

R

Represents reaction rate

k

Represents the concentration of a reactant

n

Represents the constant

Reaction rate law formula

R = K[A]ⁿ

Reversible reaction

A chemical reactin that can occur in both the forward and the reverse directions

Chemical equilibrium

State in which the forward and reverse reactions balance each other because they take place at equal rates

Catalysts do not affect the

The equilibrium state nor the equilibrium constant

Law of chemical equilibrium

States that at a given temperature, a chemical system might reach a state in which a particular ratio of reactant and product concentrations has a constant value

Law of chemical equilibrium formula

aA + bB ⇌ cC + dD

Equilibrium constant

K_eq, is the numerical value of the ratio of product concentrations to reactant concentrations, with each concentration raised to the power equal to its coefficient in the balanced equation

Chemical equilibrium formula

K_eq = [C]^c[D]^d / [A]^a[B]^b

K_eq > 1

Products are strongly favored in equilibrium

K_eq < 1

Reactants are strongly favored at equilibrium

Homogeneous equilibrium

All the reactants and products are in the same physical state

Heterogeneous equilibrium

When the reactants and products are in that one physical state

La Chatelier’s principle

If a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress

Stress

Any kind of change in a system at equilibrium that upsets the equilibrium

Solubility product constant (K_sp)

The equilibrium constant expression for the dissolving of a sparingly soluble compound

The solubility product constant expression

The product of the concentrations of the dissolved ions, each rose to the power equal to the coefficient of the ion in the chemical equation

Ion product (Q_sp)

A trial value that can be compared with K_sp