Question 1
NOBr(g) is placed in a flask at an initial concentration of 0.100 M and decomposes: 2NOBr(g) ⇌ 2NO(g) + Br₂(g). At equilibrium, [Br₂] = 0.0150 M. What is Kc at this temperature?
AP Chemistry free-response questions: how they are scored
Section II has seven questions: three long ones worth 10 points and four short ones worth 4. Each question has several parts and every point is earned on its own, so a clear calculation or a precise sentence for each part beats a long essay.
| Long questions | 3, worth 10 points each |
|---|---|
| Short questions | 4, worth 4 points each |
| Time | 105 minutes for all seven |
| Weight | 50% of the exam score |
What the questions test
- All six science practices appear in Section II.
- Mathematical Routines carry the most weight: 43–53% of the free-response score.
- Argumentation is 15–24%, Question and Method 10–16% and Representing Data and Phenomena 8–16%.
- Model Analysis is 5–9% and Models and Representations 2–4%.
Earning each point
- Show the setup of every calculation, with units, so a correct method can still earn credit.
- Answer the task verb: calculate gives a number with units, explain gives how or why, justify gives the evidence and reasoning behind a claim.
- Explain at the level of particles: name the forces, the structure or the collisions involved.
- Draw what is asked for, such as a Lewis diagram, a particle drawing or a labeled graph, and keep it consistent with your answer.
- Answer every part: a later part often still scores even if an earlier value was wrong.
Try 2 questions
Question 2
A galvanic cell is built from Zn(s) in 1.0 M Zn²⁺(aq) and Ag(s) in 1.0 M Ag⁺(aq) at 25 °C. The standard reduction potentials are Zn²⁺/Zn −0.76 V and Ag⁺/Ag +0.80 V. What is E° for the cell?
Next step
Questions people ask
How many FRQs are on the AP Chemistry exam?
Seven: three long questions worth 10 points each and four short questions worth 4 points each, in 105 minutes.
How much is the free-response section worth?
Half of the exam score, the same as the 60 multiple-choice questions.
Are AP Chemistry free-response answers typed?
No. You read the questions in Bluebook and handwrite your answers in a paper booklet. Our practice desk takes typed answers, and asks you to describe any drawing in words, so each point can be marked.