Rate of Reactions Flashcards

Flashcards covering key vocabulary and concepts related to rates of reaction.

Rate of Reaction Factors

Concentration, pressure, particle size, temperature, and catalysts affect reaction rates.

Catalyst Definition

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

Activation Energy

Pathways with lower activation energies increase reaction rates.

Reaction Rate Measurement

Track the rate of reactant usage or product formation.

Methods to Measure Reaction Rate

Change in mass, volume of gas, or amount of precipitate over time.

Rate of Reaction Graph Analysis

Relate the rate of reaction to the gradient of a graph.

Rate of Reaction and Time

The rate of a chemical reaction is a measure of how fast a reaction takes place with respect to time.

Law of Conservation of Mass

In a chemical reaction, the mass of the products equals the mass of the reactants.

Reaction Completion

Reaction is complete when the mass of the system remains constant, and the gradient is zero.

Rate of Reaction Experimental Error

Human reaction time when starting or stopping the stopwatch.

Sodium Thiosulfate Reaction

Na2S2O3(aq) + 2HCl(aq) → SO2(g) + H2O(l) + 2NaCl(aq) + S(s); measures precipitate formation.

Rate of Reaction and Temperature

Inversely proportional to the time taken for the cross to disappear.

Collision Theory

Reacting particles must collide with sufficient energy and correct orientation for a reaction to occur.

Activation Energy (Ea)

The minimum energy reactant particles must possess for a chemical reaction to occur.

Factors Affecting Effective Collisions

Concentration, pressure, particle size, temperature, and catalyst.

Catalyst

A substance that increases the rate of reaction (both forward and backward for reversible reactions).

Industrial Catalyst Example

Iron in the manufacture of ammonia (Haber process).

Biological Catalyst Example

Enzymes catalyzing sugar conversion into ethanol.

Catalyst effect

Provide an alternative pathway with a lower activation energy.

Effect of Increased Pressure on reactions

At higher pressure, there are more reacting particles per unit volume. There is an increased frequency of effective collisions, rate of reaction increases. Note: Effect of pressure applies to gaseous reactants only.

Effect of smaller particle size on reactions

The smaller the size of the particle, the greater the surface area for reactant particles to react. There is an increased frequency of effective collisions, hence rate of reaction increases.