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UAT-UK SPEC: C11MODULE: CHEMISTRYTOPIC ID: ARCH-C-10

Calorimetry (q = mcΔT, ΔH = -q/n), Hess's Law Cycles & Mean Bond Enthalpies (ΣE(broken) - ΣE(formed))

Master Calorimetry (q = mcΔT, ΔH = -q/n), Hess's Law Cycles & Mean Bond Enthalpies (ΣE(broken) - ΣE(formed)) on the ESAT Chemistry paper. Traditional classroom derivations waste valuable seconds. Using the 2-step Sub-90 invariant elimination method compresses solve time to 40s, saving +110s per question.

Standard Classroom Time
150s
Textbook multi-line derivations bleed exam clock
Sub-90 Target Pace
40s
Comfortably below the 88.8s per-question limit
Time Saved for Review
+110s
Banks clock buffer across 27 questions

2-Step Sub-90 Shortcut Formula

How to eliminate intermediate algebra and solve under 45 seconds.

Launch Interactive Lesson
STEP 1 • SETUP INVARIANT (LINE 1)10–15s
Line 1 (Total Mass 100 g100\text{ g}): q=100×4.2×6.0=2520 J=2.52 kJq = 100 \times 4.2 \times 6.0 = 2520\text{ J} = 2.52\text{ kJ}.

Establish the structural invariant and eliminate impossible options immediately.

STEP 2 • FAST SOLVE (LINE 2)15–25s
Line 2 (Exothermic Sign & Moles): ΔH=−2.520.050=−50.4 kJ mol−1\Delta H = -\frac{2.52}{0.050} = -50.4\text{ kJ mol}^{-1} (25s).

Evaluate the simplified expression using integer factoring or unit elimination.

Distractor Trap Forensics

The predictable cognitive traps engineered by examiners into the wrong options.

TRAP #1sign_or_direction_flip

Calculating ΔH = sum(E(formed)) - sum(E(broken)) or giving positive +ΔH when temperature rises

Reversing BENDOMEX (Breaking = Endothermic +, Making = Exothermic -) or forgetting ΔH < 0 for a temperature rise.

Sub-90 Fix: Test invariants before expanding equations.
TRAP #2subsystem_isolation_trap

Using mass of solid solute (or fuel burned) as m in q = mcΔT instead of the mass of water/solution heated

Substituting reactant mass m(solid) into q = m(water) * c * ΔT instead of the aqueous solution mass.

Sub-90 Fix: Test invariants before expanding equations.
TRAP #3fence_post_or_domain_trap

Counting 3 C-H bonds instead of 4 in CH4, or forgetting 2 O-H bonds per H2O molecule (2 * 2 = 4 O-H bonds in 2H2O)

Under-counting bonds inside polyatomic molecules when multiplying by stoichiometric coefficients.

Sub-90 Fix: Test invariants before expanding equations.

Try 1 Timed Question: Calorimetry (q = mcΔT, ΔH = -q/n), Hess's Law Cycles & Mean Bond Enthalpies (ΣE(broken) - ΣE(formed))

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Full Lesson All 15 Questions (ARCH-C-10)
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ARCH-C-10: Calorimetry (q = mcΔT, ΔH = -q/n), Hess's Law Cycles & Mean Bond Enthalpies (ΣE(broken) - ΣE(formed)) (Sample)Chemistry
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SUB-90 ZONE (<35S)
0.0s35s Sub-9090s ESAT Budget150s Classroom
Question 1 of 1ARCH-C-10 (6-Card Lesson)Format: Standard 5-Option
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Question 1 of 1 • 90s Target

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