To get a 5 in 1972, you needed to have memorized:
By: AP Curriculum Historians
For decades, the Advanced Placement (AP) Chemistry exam has been the gold standard for high school college-level chemistry. While modern students focus on quantum mechanics and organic spectroscopy, the 1972 exam represents a fascinating "retro" challenge—a test built in an era of slide rules, log tables, and heavy emphasis on stoichiometry, equilibrium, and descriptive chemistry.
If you are searching for 1972 AP Chemistry free response answers, you are likely a tutor, a history buff, or a student using the legendary "Old AP Exams" for ultra-hardcore preparation. You have come to the right place.
Disclaimer: The original 1972 AP Chemistry exam is copyrighted by the College Board. The following answers are provided for educational commentary and historical analysis based on declassified materials and retroactive scoring guidelines. They are not official College Board publications but are accurate to the chemistry of the era. 1972 ap chemistry free response answers
Step 1: Determine standard cell potential (E°_cell).
Step 2: Write the Nernst equation. For Zn + Cu²⁺ → Zn²⁺ + Cu: ( n = 2 ) electrons. [ E_cell = E°_cell - \frac0.0592n \log Q ] [ Q = \frac[Zn^2+][Cu^2+] = \frac0.100.0010 = 100 ]
Step 3: Calculate. [ E_cell = 1.10 - \frac0.05922 \log(100) ] [ \frac0.05922 = 0.0296 ] [ \log(100) = 2 ] [ E_cell = 1.10 - (0.0296 \times 2) = 1.10 - 0.0592 ] [ E_cell = 1.0408 , \textV ]
Answer (1972 style): 1.04 V (accept 1.04 to 1.05 V). To get a 5 in 1972, you needed
Method: Use the weak acid approximation ( [H^+] = \sqrtC \cdot K_a ).
Step 1: [ [H^+] = \sqrt(0.100)(1.8 \times 10^-5) ] [ [H^+] = \sqrt1.8 \times 10^-6 ]
Step 2: Square root manually (slide rule method).
Step 3: Calculate pH.
Check approximation: ( [H^+]/C = 0.00134 / 0.100 = 1.34% ) (<5% → valid).
Answer: pH = 2.87
The 1972 scoring guidelines gave full credit for 2.87 or 2.9.
Typical Prompt: A 0.500 g sample of a compound containing only carbon, hydrogen, and oxygen is burned in excess oxygen. It produces 1.200 g of CO2 and 0.500 g of H2O. Find the empirical formula. Step 1: Determine standard cell potential (E°_cell)
Before diving into the answers, it is crucial to understand the format. In 1972, the AP Chem exam was divided into two sections:
The free response section typically contained 6 to 8 "problems." Unlike today’s exam (which features long-form questions and short-answer parts), the 1972 exam required intense manual calculation. Calculators were prohibited.