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🧪AP Chemistry
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🧪AP Chemistry

FRQs 1–3 – Long Answer
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Unit 1: Atomic Structure and Properties
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Each FRQ type tests specific skills taught in particular units. Here's why certain units appear for each question type:

This mapping reflects College Board's exam structure - each FRQ type tests specific skills that are taught in particular units.

Practice FRQ 1 of 351/35

1. Answer the following questions about sulfur and its compounds.

A mass spectrum for a sample of naturally occurring sulfur is shown in Figure 1.

Figure 1. Mass spectrum of naturally occurring sulfur (relative abundance of isotopes)

Figure 1
A.
i.

Calculate the average atomic mass of sulfur using the data in Figure 1. Report your answer to four significant figures.

ii.

Identify the number of neutrons in the isotope represented by the peak at 33.97 amu in Figure 1.

The photoelectron spectrum of sulfur is shown in Figure 2.

Figure 2. Photoelectron spectrum (PES) of sulfur showing binding energies and relative numbers of electrons

Figure 2
B.
i.

Identify the subshell corresponding to the peak at 16.5 MJ/mol in Figure 2.

ii.

Explain why the peak at 2.05 MJ/mol is located to the left of the peak at 1.00 MJ/mol in Figure 2.

C.

The first ionization energy of sulfur is 1000 kJ/mol, while the first ionization energy of phosphorus is 1012 kJ/mol. Explain this observation using principles of atomic structure.

A student investigates the properties of a pure sample of dimethyl sulfide, C2H6SC_2H_6SC2​H6​S.

D.

Calculate the mass percent of sulfur in C2H6SC_2H_6SC2​H6​S.

E.

A student obtains a 1.501.501.50 g sample of pure C2H6SC_2H_6SC2​H6​S. Calculate the total number of hydrogen atoms in the sample.

F.

In a separate experiment, the student analyzes a mixture containing C2H6SC_2H_6SC2​H6​S and a non-sulfur containing impurity. Elemental analysis determines that the mixture contains 12.5% sulfur by mass. Calculate the mass percent of C2H6SC_2H_6SC2​H6​S in the mixture.

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Free Response Question Practice

This practice environment simulates the AP AP Chemistry Free Response Questions section. Here are some guidelines:

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