AP CHEMISTRY
WEEK 5
Study Guide
, AP CHEMISTRY
WEEK 5 STUDY GUIDE
Message to Lumist AP Learners
Hi AP Campers! This week marks the half-way point in the course. Congratulations
on completing half of the AP Chemistry Study Camp. This week’s unit is Kinetics, which
covers 7-9% of the final exam.
Reaction kinetics refers to the rate of a reaction. We will first define what rate means.
We will also learn how to express rate using the rate law equation. Next, we will discuss
reaction orders. This week also looks at the collision model of a reaction. Lastly, we will
learn about reaction energy diagrams and catalysts.
This guide includes tips to help you avoid common misunderstandings and remember
key concepts. The end of this guide has a problem set with questions you can expect on
the exam. There is also a bonus question for students who want extra practice and a bit
of a challenge.
Good luck!
Chapter Overview: Topics & Concepts
5.1 Reaction Rates
• Reaction rate: change in concentration over time
𝒂𝑨 + 𝒃𝑩 → 𝒅𝑫 + 𝒆𝑬
• Change in concentration of products ↑ as reaction proceeds
• Change in concentration of reactants ↓ as reaction proceeds
• Reaction rates are written as positive values. Therefore, the rate calculated using
reactants is multiplied by -1.
∆[𝐴] ∆[𝐵]
𝑟𝑎𝑡𝑒 𝑜𝑓 𝑑𝑖𝑠𝑎𝑝𝑝𝑒𝑎𝑟𝑎𝑛𝑐𝑒 𝑜𝑓 𝐴 = − 𝑟𝑎𝑡𝑒 𝑜𝑓 𝑓𝑜𝑟𝑚𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐷 =
∆𝑡 ∆𝑡
• IUPAC recommends a general rate of a reaction using the following expression:
1 ∆[𝐴] 1 ∆[𝐵] 1 ∆[𝐷 ] 1 ∆[𝐸 ]
𝑟𝑎𝑡𝑒 𝑜𝑓 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 = − =− = =
𝑎 ∆𝑡 𝑏 ∆𝑡 𝑑 ∆𝑡 𝑒 ∆𝑡
02
, AP CHEMISTRY
WEEK 5 STUDY GUIDE
Factors Affecting Rate
• In order for a reaction to occur, molecules have to collide at the right angle with the
right amount of energy.
1. Concentration
Increases collisions. ↑ reactant concentration, ↑reaction rate
2. Surface Area
More molecules are exposed to react. ↑ Surface Area, ↑ reaction rate
3. Temperature
Increases kinetic energy of molecules. ↑ Temperature, ↑ reaction rate
4. Catalyst
Catalyst: a compound added to a reaction to increase reaction rate.
Helps molecules collide at an appropriate orientation.
Catalysts do not take part in the reaction. They are remade in the reaction process.
Catalysts ↑ reaction rate.
5.2 Introduction to the Rate Law & Concentration Changes Over Time
• The rate law or rate equation allows us to calculate the rate of a reaction given reactant
concentrations
• Consider the following equation:
𝑎𝐴 + 𝑏𝐵 → 𝑔𝐺 + ℎ𝐻
𝑤ℎ𝑒𝑟𝑒 𝑎, 𝑏, 𝑔 & ℎ 𝑎𝑟𝑒 𝑡ℎ𝑒 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡𝑠 𝑖𝑛 𝑡ℎ𝑒 𝑏𝑎𝑙𝑎𝑛𝑐𝑒𝑑 𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛
• The rate law for this reaction would be the following:
𝑟𝑎𝑡𝑒 = 𝑘 [𝐴]𝑚 [𝐵]𝑛
• [A] and [B] are the concentrations of the reactants. If the reactants are gases, pressure
can be used instead of concentration ex. 𝑟𝑎𝑡𝑒 = 𝑘(𝑃𝐴 )𝑚 (𝑃𝐵 )𝑛
• m and n are generally positive, whole number exponents (could be 0, negative, or a
fraction) determined experimentally
• Note: m and n are NOT the same as the stoichiometric coefficients a and b
03
WEEK 5
Study Guide
, AP CHEMISTRY
WEEK 5 STUDY GUIDE
Message to Lumist AP Learners
Hi AP Campers! This week marks the half-way point in the course. Congratulations
on completing half of the AP Chemistry Study Camp. This week’s unit is Kinetics, which
covers 7-9% of the final exam.
Reaction kinetics refers to the rate of a reaction. We will first define what rate means.
We will also learn how to express rate using the rate law equation. Next, we will discuss
reaction orders. This week also looks at the collision model of a reaction. Lastly, we will
learn about reaction energy diagrams and catalysts.
This guide includes tips to help you avoid common misunderstandings and remember
key concepts. The end of this guide has a problem set with questions you can expect on
the exam. There is also a bonus question for students who want extra practice and a bit
of a challenge.
Good luck!
Chapter Overview: Topics & Concepts
5.1 Reaction Rates
• Reaction rate: change in concentration over time
𝒂𝑨 + 𝒃𝑩 → 𝒅𝑫 + 𝒆𝑬
• Change in concentration of products ↑ as reaction proceeds
• Change in concentration of reactants ↓ as reaction proceeds
• Reaction rates are written as positive values. Therefore, the rate calculated using
reactants is multiplied by -1.
∆[𝐴] ∆[𝐵]
𝑟𝑎𝑡𝑒 𝑜𝑓 𝑑𝑖𝑠𝑎𝑝𝑝𝑒𝑎𝑟𝑎𝑛𝑐𝑒 𝑜𝑓 𝐴 = − 𝑟𝑎𝑡𝑒 𝑜𝑓 𝑓𝑜𝑟𝑚𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐷 =
∆𝑡 ∆𝑡
• IUPAC recommends a general rate of a reaction using the following expression:
1 ∆[𝐴] 1 ∆[𝐵] 1 ∆[𝐷 ] 1 ∆[𝐸 ]
𝑟𝑎𝑡𝑒 𝑜𝑓 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 = − =− = =
𝑎 ∆𝑡 𝑏 ∆𝑡 𝑑 ∆𝑡 𝑒 ∆𝑡
02
, AP CHEMISTRY
WEEK 5 STUDY GUIDE
Factors Affecting Rate
• In order for a reaction to occur, molecules have to collide at the right angle with the
right amount of energy.
1. Concentration
Increases collisions. ↑ reactant concentration, ↑reaction rate
2. Surface Area
More molecules are exposed to react. ↑ Surface Area, ↑ reaction rate
3. Temperature
Increases kinetic energy of molecules. ↑ Temperature, ↑ reaction rate
4. Catalyst
Catalyst: a compound added to a reaction to increase reaction rate.
Helps molecules collide at an appropriate orientation.
Catalysts do not take part in the reaction. They are remade in the reaction process.
Catalysts ↑ reaction rate.
5.2 Introduction to the Rate Law & Concentration Changes Over Time
• The rate law or rate equation allows us to calculate the rate of a reaction given reactant
concentrations
• Consider the following equation:
𝑎𝐴 + 𝑏𝐵 → 𝑔𝐺 + ℎ𝐻
𝑤ℎ𝑒𝑟𝑒 𝑎, 𝑏, 𝑔 & ℎ 𝑎𝑟𝑒 𝑡ℎ𝑒 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡𝑠 𝑖𝑛 𝑡ℎ𝑒 𝑏𝑎𝑙𝑎𝑛𝑐𝑒𝑑 𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛
• The rate law for this reaction would be the following:
𝑟𝑎𝑡𝑒 = 𝑘 [𝐴]𝑚 [𝐵]𝑛
• [A] and [B] are the concentrations of the reactants. If the reactants are gases, pressure
can be used instead of concentration ex. 𝑟𝑎𝑡𝑒 = 𝑘(𝑃𝐴 )𝑚 (𝑃𝐵 )𝑛
• m and n are generally positive, whole number exponents (could be 0, negative, or a
fraction) determined experimentally
• Note: m and n are NOT the same as the stoichiometric coefficients a and b
03
