Unit 1: Chemical Systems Practice Flashcards

Vocabulary-style flashcards covering chemical kinetics, collision theory, factors affecting reaction rates, dynamic equilibrium, and industrial chemical processes based on Grade 10 MYP Year 5 Unit 1.

Physical Change

A change that does not result in the formation of a new substance and simply alters the state of the substance involved, such as ice melting into water.

Chemical Change

A process that results in the formation of a new substance.

Rate of Reaction

The rate of change in concentration of either reactants or products with respect to time, often defined as $\frac{\text{increase in concentration of product}}{\text{time}}$ or $\frac{\text{decrease in concentration of reactant}}{\text{time}}$.

Kinetic-Molecular Theory of Matter

The theory stating that particles in a substance move randomly because of the kinetic energy they possess, with collisions and movements being random in nature.

Activation Energy ($E_a$)

The minimum amount of energy needed for particles to react and form a product.

Collision Theory

The concept that for a reaction to occur, particles must collide with the correct orientation and with sufficient energy.

Rate of Reaction Units

$$mol\,dm^{-3}\,time^{-1}$$

Single Displacement Reaction Example

$$Mg(s) + 2HCl(aq) \rightarrow MgCl_2(aq) + H_2(g)$$

Concentration (Factor)

Increasing this factor increases the frequency of collisions between reactant particles, thereby increasing the rate of reaction.

Particle Size (Factor)

Decreasing this factor increases the total surface area, allowing more contact and a higher probability of collisions between reactants in heterogeneous reactions.

Pressure (Factor)

For reactions involving gases, increasing this factor compresses the gas and increases the frequency of collisions, thus increasing the rate of reaction.

Catalyst

A substance that increases the rate of a chemical reaction without undergoing permanent chemical change, typically by providing an alternate route with a lower activation energy.

Temperature (Factor)

Increasing this causes an increase in average kinetic energy, shifting the Maxwell–Boltzmann distribution peak to the right and increasing the proportion of particles with energy greater than the activation energy.

Enzymes

Biological catalysts that catalyze reactions efficiently under mild conditions; they exhibit specificity for their substrates.

Lactase

An enzyme that breaks down lactose, the sugar found in milk, into glucose and galactose.

Reversible Reaction

A reaction where the products can react to reform the original reactants, denoted by the half arrows symbol $\rightleftharpoons$.

Dynamic Equilibrium

A state in a closed system where the rate of the forward reaction is the same as the rate of the backward reaction, and the concentrations of reactants and products remain constant.

Le Chatelier’s Principle

The principle stating that if a change is made to a system at dynamic equilibrium, the position of the equilibrium moves to minimize or counteract that change.

Position of Equilibrium

The relative amounts of products and reactants in an equilibrium mixture; shifting 'left' increases reactant concentration, while shifting 'right' increases product concentration.

Haber Process

An industrial equilibrium process used to produce ammonia from nitrogen and hydrogen.

Maxwell-Boltzmann Distribution

A curve representing the total number of particles in a sample as a function of their kinetic energy, where the area under the curve is equal for a given sample regardless of temperature.