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AP Chem



Unit 4

4.0 Unit 4 Overview: Chemical Reactions

2 min readaugust 20, 2020

Dalia Savy

From the College Board

👀 Develop Your Understanding of this unit

According to the College Board, "This unit explores chemical transformations of matter by building on the physical transformations studied in Unit 3. Chemical changes involve the making➡️⬅️ and breaking⬅️➡️ of chemical bonds. Many properties of a chemical system can be understood using the concepts of varying strengths of chemical bonds and weaker intermolecular interactions. When chemical changes occur, the new substances formed have properties that are distinguishable from the initial substance or substances.
Chemical reactions are the primary means by which transformations in matter occur. Chemical equations are a representation of the rearrangement of atoms that occur during a chemical reaction. In subsequent units, students will explore rates at which chemical changes occur."

🔎 Big Idea Questions

  • What makes fireworks explode?
  • Why is the mass of a raw egg different than a boiled egg?
  • What are the processes related to changes in a substance?

👨‍🔬What is Unit 4 About?

Unit 4 is about all of the chemical reactions💥 behind processes we see everyday! There are so many different types of chemical reactions and with this unit, you begin to understand the mechanics behind each of them🤓. There is quite a bit of math that comes with this unit as well. It also sets up the foundations for future units so it's best to nail 🔩 this unit before continuing on with the course.
🧠About 7-9% of the exam is about this unit!

📝Key Vocabulary

Physical ChangeChemical ChangeSynthesis ReactionsDecomposition Reactions
Single Replacement ReactionsDouble Replacement ReactionsCombustion ReactionsDissociation
InsolubleSpectator IonsNet Ionic EquationComplete Ionic Equation
StoichiometryTitrationEquivalence pointConjugate Base
Conjugate AcidLimiting ReactantExcessNeutralization
Amphiprotic RedoxOxidation #Protons

🤔What you'll Learn

  • The difference between a physical and chemical change
  • The different types of reactions
  • How to write out a net ionic equation
  • What spectator ions are and what effect they have on a reaction
  • How to balance chemical equations
  • How to perform stoichiometry
  • How to perform a titration
  • How to identify conjugate acids and bases
  • How to find the limiting reactant (LR)
  • How to find the concentration of ions
  • Identify which elements were oxidized and which were reduced

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Unit 2: Molecular and Ionic Compound Structures and Properties
Unit 3: Intermolecular Forces and Properties
Unit 5: Kinetics
Unit 6: Thermodynamics
Unit 7: Equilibrium
Unit 8: Acids and Bases
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