✍️ Free Response Questions
AP Chemistry Free Response Questions
⚛️ Unit 1 - Atomic Structure and Properties
1.1Moles and Molar Mass
1.2Mass Spectroscopy of Elements
1.3Elemental Composition of Pure Substances
1.4Composition of Mixtures
1.5Atomic Structure and Electron Configurations
1.6Photoelectron Spectroscopy & Graph Interp.
🤓 Unit 2 - Molecular and Ionic Compound Structures and Properties
2.0Unit 2 Overview: Molecular and Ionic Bonding
2.1Types of Chemical Bonds
2.2Intramolecular Force and Potential Energy
2.3Ionic Bonding and Ionic Solids
2.4Metallic Bonding and Alloys
2.5Lewis Dot Diagrams
2.6Resonance and Formal Charge
🌀 Unit 3 - Intermolecular Forces and Properties
3.0Unit 3 Overview: Intermolecular Forces and Properties
3.2Properties of Solids
3.3Solids, Liquids, and Gases
3.4The Ideal Gas Law
3.5The Kinetic Molecular Theory of Gases
3.6Deviations from the Ideal Gas Law
3.7Mixtures and Solutions
3.8Representations of Solutions
3.9Separation of Solids/Mixtures
3.10Solubility and Solubility Rules
3.11Spectroscopy and the Electromagnetic Spectrum
3.12Quantum Mechanics and the Photoelectric Effect
🧪 Unit 4 - Chemical Reactions
4.0Unit 4 Overview: Chemical Reactions
4.1Recognizing Chemical Reactions
4.2Net Ionic Equations
4.4Physical vs. Chemical Changes
4.5Stoichiometry & Calculations
4.6Titrations - Intro and Calculations
4.8Intro to Acid-Base Neutralization Reactions
👟 Unit 5 - Kinetics
5.0Unit 5 Overview: Kinetics
5.1Defining Rate of Reaction
5.2Introduction to Rate Laws
5.3Rate and Concentration Change
5.4Writing Rate Laws
5.5Collision Model of Kinetics
5.6Reaction Energy and Graphs w/ Energy
5.7Reaction Mechanisms and Elementary Steps
5.8Writing Rate Laws Using Mechanisms
🔥 Unit 6 - Thermodynamics
6.0 Unit 6 Overview: Thermochemistry and Reaction Thermodynamics
6.1Endothermic Processes vs. Exothermic Processes
6.2Energy Diagrams of Reactions
6.3Kinetic Energy, Heat Transfer, and Thermal Equilibrium
6.4Heat Capacity and Coffee-Cup Calorimetry
6.5Phase Changes and Energy
6.6Introduction to Enthalpy of Reaction
6.7Bond Enthalpy and Bond Dissociation Energy
6.8Enthalpies of Formation
⚖️ Unit 7 - Equilibrium
🍊 Unit 8 - Acids and Bases
8.0Unit 8 Overview: Acids and Bases
8.1Introduction to Acids and Bases
Unit 9 - Applications of Thermodynamics
🤺 AP Chemistry Essentials
🧐 Multiple Choice Questions
AP Chemistry Self-Study and Homeschool
October 7, 2020
Fluidity - the ability for molecules to flow past one another
Compressibility - a measure of volume change of a substance when pressure is applied
Let’s look over some of the characteristic properties of the states of matter:
As we learned in the last key topic, solids can either be crystalline or amorphous. Crystalline solids have a structure and 3D order, while amorphous solids have considerable disorder within their structures.
Regardless of the type of solid, all solids retain their own shape and volume. They don’t expand to fill their container. This is because the particles in a solid are packed very closely together and cannot move.
The intermolecular forces are strong enough to keep the particles in place.
They are virtually incompressible, don’t flow, and the diffusion process within a solid occurs extremely slowly.
Liquids assume the shape of a portion of the container it occupies. Liquids do NOT expand to fill their container, they just fill the space that is provided by the container.
Since liquid particles aren't tightly packed together, they have the ability to flow past one another (fluidity).
The intermolecular forces are strong enough to hold the molecules closely together, but not strong enough to hold them in place.
Liquids are virtually incompressible, flow readily, and diffusion within a liquid occurs slowly.
Surface Tension is when molecules on a surface of a liquid experience a net inward force.
The stronger the IMFs, the higher the surface tension.
You see this all the time!
Image Courtesy of Gizmodo
Whenever you turn the sink on at a low pressure, the particles always form a spherical shape. This occurs because of the high surface tension of water as a result of its strong hydrogen bonding (IMFS). Here is a particle representation of surface tension:
Image Courtesy of Pinterest
Capillary action is the spontaneous rising of a liquid. It often happens with polar liquids that have strong IMFs. You could see this when you put a paper towel🧻 in contact with a puddle. The water will slowly rise up the towel due to capillary action.
There are two different types of forces involved:
Cohesive Forces: forces between H2O molecules
Adhesive Forces: forces between molecules and the container
Remember the typical meniscus (bottom right image) you see when you do experiments? That occurs when the adhesive forces are stronger than the cohesive forces, so the water is more strongly attracted to the graduated cylinder🧪.
Image Courtesy of Bartleby
I bet you've never seen Mercury in glass! Well that creates an upside down meniscus, which is called a convex meniscus. This occurs because the forces between the mercury molecules are stronger than the forces between the molecules and the glass (cohesive>adhesive).
Viscosity is a measure of a liquid's resistance to flow. The stronger the IMFs, the higher the viscosity and the thicker the liquid. You see this with syrup🥞.
Gases assume the volume and shape of their container.
Gas particles move rapidly in straight lines; more about the behavior of gases is covered in the rest of this unit!
The molecules have enough energy to overcome any intermolecular forces that exist, therefore allowing them to move freely.
They are compressible, flow readily, and expand to fill the container. Diffusion within a gas occurs rapidly.
Image Courtesy of the Schools of King Edward VI in Birmingham
Density measures how compact a substance is! The formula for Density is D = m/V, or density = mass divided by volume.
It is good to remember that solids are usually the most dense out of the three phases and gases are usually the least dense since they flow freely in open space.
The following question is from a Fiveable live stream!
A student measured the mass of a sealed 644 mL flash that contained air. The student then flushed the flask with an unknown gas, resealed it, then measured the mass again. The air and the unknown gas were at STP. Calculate the mass of the unknown gas. The density of air at STP is 1.29 g/L.
|Volume of sealed flash||644 mL|
|Mass of Sealed flask and air||121.03 g|
|Mass of Sealed Flask and Unknown Gas||122.60 g|
Before answering the question, let's note that the air is in a sealed flask. This means that it cannot escape into the atmosphere so the most it could do is fill the shape of the container.
Also, don't worry about STP yet, we'll go over that in the next key topic.
First Step - Find the mass of the air: Since we are given both the density of the air and the volume of the sealed flask, we can find the mass. However, they give us a density in g/L and a volume in mL, so first we have to convert 644 mL into .644 L by simply moving the decimal 3 to the left. D = M/V --> 1.29 = M/.644 --> M = 0.831 g
Second Step - Find the mass of the flask: Since we now know the mass of the air and the mass of both the air and the flask, we can just subtract. 121.03 g - 0.831 g = 120.20 g
Final Step - Find the mass of the unknown gas: They have given us the mass of both the sealed flask and the unknown gas. Since we know the mass of the sealed flask alone, we can just subtract and get our final answer! 122.60 g - 120.20 g = 2.40 g
To remember the differences between a solid, liquid, and gas, think about your own experiences in life. For example, liquids, like water, will flow freely whereas a solid, like ice, maintains its shape no matter what container it is in. Here's a chart from our states of matter live stream to help out:
🎥Watch: AP Chemistry - Solids, Liquids, and Gases
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