AP Chemistry – AP Chemistry – Final Calculation Set
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Time: 20–25 minutes
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No calculator for simple logs (AP style)
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Show setup (very important)
Question 1 (pH – Basic)
What is the pH of 1.0 × 10⁻³ M HCl?
A. 2
B. 3
C. 4
D. 11
... Correct Answer: B Why: pH = -log(10⁻³) = 3 Trap: Don’t overthink logs Fix: Exponent = pH
Question 2(pOH → pH)
If pOH = 5, what is pH?
A. 5
B. 7
C. 9
D. 14
... Correct Answer: C Why: pH + pOH = 14 → pH = 9 Trap: Forgetting formula Fix: Always: pH + pOH = 14
Question 3(Dilution)
A 1.0 M acid is diluted to 0.10 M. What happens to pH?
A. increases by 1
B. decreases by 1
C. no change
D. doubles
... Correct Answer: A Why: 10× dilution → pH increases by 1 Trap: Mixing concentration vs pH Fix: Each factor of 10 → ±1 pH
Question 4(K Expression)
For:
A ⇌ B
If [A] = 2.0 M and [B] = 4.0 M, what is K?
A. 0.5
B. 2
C. 4
D. 8
... Correct Answer: B Why: K = [B]/[A] = 4/2 = 2 Trap: Reversing ratio Fix: Products / Reactants
Question 5(ICE Table Logic – Conceptual Math)
If K = 100, what does this mean?
A. mostly reactants
B. mostly products
C. equal amounts
D. no reaction
... Correct Answer: B Why: Large K → products favored Trap: Thinking rate vs equilibrium Fix: K = position, not speed
Question 6(Rate Factor)
If concentration doubles, reaction rate:
A. halves
B. doubles
C. stays same
D. stops
... Correct Answer: B Why: More particles → more collisions Trap: Overcomplicating Fix: More concentration → faster rate
Question 7(ΔG)
Which indicates a spontaneous reaction?
A. ΔG > 0
B. ΔG = 0
C. ΔG < 0
D. ΔH > 0
... Correct Answer: C Why: Negative ΔG → spontaneous Trap: Confusing ΔH and ΔG Fix: ΔG decides spontaneity
Question 8(Pressure + Moles)
For:
2A(g) ⇌ B(g)
If pressure increases, what happens?
A. shift left
B. shift right
C. no change
D. depends
... Correct Answer: B Why: Left = 2 moles, Right = 1 → shift right Trap: Not counting moles Fix: Pressure ↑ → fewer moles
Question 9(pH of Diluted Base)
If a base is diluted, what happens to pH?
A. increases
B. decreases
C. no change
D. becomes neutral
... Correct Answer: B Why: [OH⁻] decreases → less basic → pH decreases Trap: Mixing acid logic Fix: Dilute base → pH ↓
Question 10(Log Thinking)
Which has lowest pH?
A. 10⁻²
B. 10⁻³
C. 10⁻⁴
D. 10⁻⁵
... Correct Answer: A Why: Higher [H⁺] → lower pH Trap: Confusing exponent direction Fix: Less negative exponent = stronger acid
FRQ - FINAL FRQ (Calculation Style)
A solution has [H⁺] = 1.0 × 10⁻⁶ M.
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Calculate pH
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State if solution is acidic, basic, or neutral
... Perfect Answer: pH = -log(1.0 × 10⁻⁶) = 6 Since pH