IB Chemistry Topic R2.2.3 Factors Affecting the Rate of Reaction Revision Notes (SL/HL)

IB Chemistry Topic R2.2.3 Factors Affecting the Rate of Reaction Revision Notes (SL/HL) | RevisionDojo

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Collision Theory: The Foundation of Reaction Rates

Chemical reactions happen when particles (atoms, ions, or molecules) collide with enough energy and the correct orientation to break and form bonds.
Collision theory is covered in R2.2.2, so here the focus is on how changing conditions changes the rate.

Hint

The rate of a reaction depends on two key factors: the frequency of collisions and the proportion of successful (or "effective") collisions.
Each factor we’ll explore influences one or both of these aspects.

Concentration: Increasing Collision Frequency

Increasing the concentration of reactants increases the number of particles in a given volume, leading to more frequent collisions.
Effect on reaction rate: Higher concentration → more collisions per second → faster reaction.

Example

In the reaction between magnesium and hydrochloric acid, increasing the concentration of $HCl$ results in more frequent collisions between $H^+$ ions and magnesium atoms, speeding up the production of hydrogen gas.

Hint

Concentration changes only affect reactions in solutions.
For pure solids or liquids, concentration does not influence the reaction rate.

Analogy

Picture a crowded room where people are constantly bumping into one another.
The more people there are, the more frequent the collisions.

Pressure: Compressing Gaseous Reactants

For reactions involving gases, increasing the pressure compresses the gas particles into a smaller volume, much like squeezing a balloon.
This increases particle density, which is analogous to increasing the concentration of a solution.

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Collision Theory: The Foundation of Reaction Rates

Chemical reactions happen when particles (atoms, ions, or molecules) collide with enough energy and the correct orientation to break and form bonds.
Collision theory is covered in R2.2.2, so here the focus is on how changing conditions changes the rate.

Hint

The rate of a reaction depends on two key factors: the frequency of collisions and the proportion of successful (or "effective") collisions.
Each factor we’ll explore influences one or both of these aspects.

Concentration: Increasing Collision Frequency

Increasing the concentration of reactants increases the number of particles in a given volume, leading to more frequent collisions.
Effect on reaction rate: Higher concentration → more collisions per second → faster reaction.

Example

Hint

Concentration changes only affect reactions in solutions.
For pure solids or liquids, concentration does not influence the reaction rate.

Analogy

Picture a crowded room where people are constantly bumping into one another.
The more people there are, the more frequent the collisions.

Pressure: Compressing Gaseous Reactants

For reactions involving gases, increasing the pressure compresses the gas particles into a smaller volume, much like squeezing a balloon.
This increases particle density, which is analogous to increasing the concentration of a solution.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

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Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

IB Chemistry R2.2.3 Factors Affecting the Rate of Reaction Notes

Collision Theory: The Foundation of Reaction Rates

Concentration: Increasing Collision Frequency

Pressure: Compressing Gaseous Reactants

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Duis aute irure dolor in reprehenderit

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Unlock the rest of this chapter with a free account

Collision Theory: The Foundation of Reaction Rates

Concentration: Increasing Collision Frequency

Pressure: Compressing Gaseous Reactants

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics