AP® Chemistry Multiple Choice Practice Problems

The video focuses on preparing for the AP Chemistry test by offering a mini test on the presenter's website and providing resources to help students. It includes a legal disclaimer about the use of the AP Chemistry name and the intention to outsmart the test's challenges. The first question discussed is a stoichiometry problem involving the reaction between iron and sulfur to form iron (II) sulfide, highlighting the concept of limiting reagents.

The video explains how to identify the Bronsted-Lowry acid conjugate base pairs from a list of options. It emphasizes the definition of acids and bases in this context and uses the concept of proton transfer to determine the correct pair. Common mistakes are also discussed, such as misidentifying strong acids and their conjugate bases or misunderstanding the difference between conjugate pairs and water's ions.

The video teaches how to interpret photoelectron spectra (PES) graphs, which are featured in recent AP exams. It explains the axes representation, the significance of peaks, and how to translate the graph into an electron configuration. The example provided walks through identifying the element aluminum based on its electron configuration derived from the PES graph.

This section discusses the concentration of ions in a saturated solution of ammonium phosphate and how to calculate it based on the given concentration of ammonium ions. The video also covers a conceptual math problem involving the titration of calcium hydroxide with hydrochloric acid, explaining how to determine the mass of calcium hydroxide in an antacid tablet.

The video covers an electrochemistry problem involving a redox titration using KMnO4 to oxidize Fe2+ ions. It emphasizes the importance of laboratory procedure in preventing errors and ensuring safety. The calculation of standard cell potential is discussed, highlighting common mistakes such as misunderstanding the mole ratio and the impact of temperature on reaction rates.

The presenter discusses the proper lab procedure before adding the KMnO4 solution to the buret in a redox titration experiment. It explains why the buret should be washed with excess permanganate solution to prevent dilution and ensure accuracy. Common incorrect assumptions are also addressed, such as the need for acidifying the permanganate solution.

The video addresses a kinetics problem involving experimental trials and initial reaction rates. It explains the method of initial rates to determine the rate law and the importance of understanding the order of reactions. The problem-solving approach involves comparing concentration changes and their effect on reaction rates, leading to the formulation of the rate law.

The video discusses how changes to a system at equilibrium can affect reaction rates, specifically how they can cause the reverse reaction to speed up. It explains the application of Le Chatelier's principle to various changes, such as adding or removing reactants or products, and changing temperature. The focus is on identifying the change that leads to the reverse reaction speeding up in the context of an exothermic reaction.

The video explores the concept of nonpolar molecules that contain polar bonds. It explains the criteria for identifying such molecules and how to eliminate options that do not meet these criteria. The discussion includes the impact of electronegativity and molecular shape on molecular polarity, leading to the identification of carbon dioxide as an example of a nonpolar molecule with polar bonds.

The presenter discusses how to compare the properties of elements like lithium and cesium based on their position in the periodic table. It covers ionization energy, atomic radius, and electronegativity, explaining how these properties change as you move down a group in the periodic table. The video uses this understanding to determine the correct answer choice regarding the properties of lithium and cesium.

The video explains Dalton's law of partial pressures in the context of a system containing neon and argon gases. It demonstrates how to calculate the partial pressure of argon when the total pressure and the molar ratios of the gases are known. The explanation involves understanding the relationship between pressure, number of moles, and molar masses of the gases.

The video helps to identify which species has a given electron configuration by analyzing the total number of electrons and comparing it to the atomic numbers and charges of possible species. It clarifies common misconceptions about ionic charges and the formation of ions, leading to the identification of the strontium ion as the correct answer.

The video presents a calorimetry problem involving the heating of magnesium and its subsequent cooling in a water-filled calorimeter. It explains how to use the specific heat capacity of magnesium and water, along with the temperatures and masses, to calculate the mass of the magnesium sample. The summary highlights the importance of accurately identifying knowns and unknowns and using the correct change in temperature for calculations.

The video discusses the calculation of standard cell potential in the context of a galvanic cell, emphasizing the need to identify the cathode and anode reactions and their respective standard reduction potentials. It outlines common mistakes such as mishandling negative values and incorrectly assuming that cell potential is affected by stoichiometry. The explanation also covers how to determine the change in mass at the electrodes during cell operation.