International Baccalaureate IB Chemistry

Chemical equations show the ratio of reactants and products in a reaction.

Deduce chemical equations when reactants and products are specified. Include the use of state symbols in chemical equations.

The mole ratio of an equation can be used to determine the masses and/or volumes of reactants and products and the concentrations of reactants and products for reactions occurring in solution.

Calculate reacting masses or volumes and concentrations of reactants and products.

The limiting reactant determines the theoretical yield. Identify the limiting and excess reactants from given data.

Distinguish between the theoretical yield and the experimental yield.

The atom economy is a measure of efficiency in green chemistry.

Calculate the atom economy from the stoichiometry of a reaction.

The rate of reaction is expressed as the change in concentration of a particular reactant/product per unit time.

Determine rates of reaction.

Species react as a result of collisions of sufficient energy and proper orientation.

Explain the relationship between the kinetic energy of the particles and the temperature in kelvin, and the role of collision geometry.

Factors that influence the rate of a reaction include pressure, concentration, surface area, temperature and the presence of a catalyst.

Predict and explain the effects of changing conditions on the rate of a reaction.

Activation energy, $E_a$, is the minimum energy that colliding particles need for a successful collision leading to a reaction.

Construct Maxwell–Boltzmann energy distribution curves to explain the effect of temperature on the probability of successful collisions.

Catalysts increase the rate of reaction by providing an alternative reaction pathway with lower $E_a$.

Sketch and explain energy profiles with and without catalysts for endothermic and exothermic reactions.

Energy profiles can be used to show the activation energy and transition state of the rate‑determining step in a multistep reaction.

Construct and interpret energy profiles from kinetic data.

The molecularity of an elementary step is the number of reacting particles taking part in that step.

Interpret the terms “unimolecular”, “bimolecular” and “termolecular”.

Rate equations depend on the mechanism of the reaction and can only be determined experimentally.

Deduce the rate equation for a reaction from experimental data.

The order of a reaction with respect to a reactant is the exponent to which the concentration of the reactant is raised in the rate equation.

The overall reaction order is the sum of the orders with respect to each reactant. 

Sketch, identify and analyse graphical representations of zero, first and second order reactions.

The Arrhenius factor, A, takes into account the frequency of collisions with proper orientations.

Determine the activation energy and the Arrhenius factor from experimental data.

A state of dynamic equilibrium is reached in a closed system when the rates of forward and backward reactions are equal.

Describe the characteristics of a physical and chemical system at equilibrium.

The equilibrium law describes how the equilibrium constant, $K$, can be determined from the stoichiometry of a reaction.

Deduce the equilibrium constant expression from an equation for a homogeneous reaction.

The magnitude of the equilibrium constant indicates the extent of a reaction at equilibrium and is temperature dependent.

Determine the relationships between K values for reactions that are the reverse of each other at the same temperature.

Le Châtelier’s principle enables the prediction of the qualitative effects of changes in concentration, temperature and pressure to a system at equilibrium.

Apply Le Châtelier’s principle to predict and explain responses to changes of systems at equilibrium.

The reaction quotient, Q, is calculated using the equilibrium expression with non‑equilibrium concentrations of reactants and products.

Calculate Q from the concentrations of reactants and products at a particular time, and determine the direction in which the reaction will proceed to reach equilibrium.

Solve problems involving values of K and initial and equilibrium concentrations of the components of an equilibrium mixture.

The equilibrium constant and Gibbs energy change, $ \Delta G $, can both be used to measure the position of an equilibrium reaction.

Calculate $ \Delta G^\circ = -RT \ln K $.