Rates of Reaction and Equilibrium Review

Flashcards covering key vocabulary and concepts related to rates of reaction, collision theory, and equilibrium.

Rate of Reaction

The amount of reactant used or product formed over time.

Units of Rate of Reaction

Can be expressed as g/s or cm3/s or mol/s.

Calculating Mean Rate of Reaction

Determined from the quantity of a reactant used or product formed and the time taken, often using data from a concentration vs. time graph.

Gradient of Tangent

Used to measure the rate of reaction at a specific time on a graph of product formed vs. time.

Measuring Reaction Rates

Can be done by monitoring the loss in mass of reactants, the volume of gas produced, or the time for a solution to become opaque or colored.

Mass Loss Measurement

Effective for reactions producing a heavy gas like carbon dioxide.

Volume of Gas Evolved

Measured over time using a gas syringe, with the graph's gradient indicating the reaction rate.

Disappearance of a Cross Experiment

Involves timing how long it takes for a cross to disappear through a mixture of acid and sodium thiosulfate as solid sulfur is produced.

Collision Theory

States that chemical reactions occur when reacting particles collide with sufficient energy (activation energy).

Activation Energy

The minimum amount of energy that particles must have to react.

Effect of Increased Concentration on Reaction Rate

Increases the frequency of collisions, thus increasing the reaction rate.

Effect of Increased Surface Area on Reaction Rate

Increases the frequency of collisions, thus increasing the reaction rate.

Effect of Increased Temperature on Reaction Rate

Increases the speed of particles, leading to more frequent and more energetic collisions, increasing the reaction rate.

Effect of Increased Pressure on Reaction Rate (Gases)

Increases the number of gas molecules in the same volume, thus increasing the frequency of collisions and reaction rate.

Catalysts

Increase the rate of reaction by providing an alternative pathway with a lower activation energy, and are not used up during the reaction.

Reversible Reactions

Reactions where products can react to produce the original reactants.

Equilibrium

Reached in a closed system when the forward and reverse reactions occur at the same rate, and the amounts of reactants and products remain constant.

Le Chatelier's Principle

If a system is at equilibrium and a change is made to any of the conditions, the system responds to counteract the change.

Effect of Changing Concentration on Equilibrium

The system will adjust to counteract the change until equilibrium is reached again.

Effect of Changing Temperature on Equilibrium

The equilibrium will shift in the endothermic direction if temperature is increased.

Effect of Changing Pressure on Equilibrium

In gaseous reactions, an increase in pressure shifts the equilibrium towards the side with fewer gaseous molecules.