Biology  by Bradford
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Free · AP Chemistry · Unit 7

Equilibrium escape room

The Fertilizer Plant

A pressure alarm has sealed your team inside the control building of an ammonia plant, where nitrogen and hydrogen are squeezed over hot iron to make fertilizer. The safety computer will not release a single door until someone proves they understand the equilibrium that runs every reactor on site. Five locks stand between you and the loading dock. Each lock poses four questions, and your answers decode into its combination. Crack all five before the overheated converter vents its gas and the whole plant is evacuated with you still locked inside.

Play it onlineTeacher pack (PDF)
  • 5 locksfour multiple-choice questions at each, 20 in all
  • About 45 minutesfor a team of three or four
  • Online or on papera link to play, or the pack to print
  • ForAP Chemistry classes, every value a question needs given (calculations on the AP equation sheet and periodic table)
  • Play linkbiologybybradford.com/escape/apc7

The five locks

Each lock’s four answers are decoded with its puzzle into a four-digit combination, so one wrong answer keeps it shut. The questions climb from recall to evaluating evidence.
  1. Lock 1 · Recall

    Front Gate Booth

    Lock dials Easy

    Each letter has a dial. Read the number the needle points to.

  2. Lock 2 · Understand

    Compressor Hall

    Symbol grid Easy

    Find the row for the question and the column for your answer. Swap the symbol for its number using the key.

  3. Lock 3 · Apply

    Catalyst Bay Hatch

    Overlay Medium

    Only segments lit on BOTH panels count. Read the number they make.

  4. Lock 4 · Analyse data

    Cooling Tower Gate

    Symbol sums Medium

    Work out each symbol's value from the sums, then swap your letters for symbols.

  5. Lock 5 · Evaluate

    Rail Siding Gate

    Number pyramid Hard

    Each brick is the sum of the two below it. The clues are high up the pyramid, so work down carefully.

Lock 1, as a team sees it

The first four questions and their decoder. The answers, and the reason for each, are in the teacher pack.

  1. A sealed flask holds colorless N₂O₄(g) and brown NO₂(g) at constant temperature. Which observation shows the system has reached equilibrium?

    1. A The brown color of the gas stays the same shade over time
    2. B The flask holds equal numbers of N₂O₄ and NO₂ molecules
    3. C The gas has turned fully colorless, so no NO₂ is left
    4. D The total pressure in the flask has risen to exactly 1 atm

  2. A reaction has K = 3.5 × 10⁻¹⁶ at 25 °C. Which best describes its equilibrium mixture at 25 °C?

    1. A Mostly products, with very little reactant remaining
    2. B Mostly reactants, with very little product present
    3. C About equal amounts of reactants and products present
    4. D No reaction at all, since K below 1 means it cannot occur

  3. Which is the equilibrium constant expression, Kc, for CaCO₃(s) ⇌ CaO(s) + CO₂(g)?

    1. A Kc = [CaO][CO₂] / [CaCO₃]
    2. B Kc = [CaCO₃] / ([CaO][CO₂])
    3. C Kc = [CO₂]
    4. D Kc = 1 / [CO₂]

  4. Which is the solubility product expression for calcium phosphate, Ca₃(PO₄)₂(s)?

    1. A Ksp = [Ca²⁺]²[PO₄³⁻]³
    2. B Ksp = [Ca²⁺][PO₄³⁻]
    3. C Ksp = [Ca²⁺]³[PO₄³⁻]² / [Ca₃(PO₄)₂]
    4. D Ksp = [Ca²⁺]³[PO₄³⁻]²

Lock dials

Easy

Each letter has a dial. Read the number the needle points to.

0123456789A
0123456789B
0123456789C
0123456789D

Running it

  1. Online: send teams the play link. They answer a lock’s four questions, decode the letters and enter the combination; after lock 5 they get a completion code to show you. Nobody needs an account.
  2. On paper: sign in (free) and print the teacher pack: question cards, the five decoders, a guide and the answer key with a reason for every answer.
  3. Your version: Edit a copy from the library to change any question, then play and print it by its own code, or build a room from the topics your class has covered.

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