UAT-UK SPEC CODE: C10 (Rates of reaction)ASSUMED MATHS 1 PREREQUISITE: M4.14FREQUENCY: MEDIUM
Reaction Rate Tangent Gradients, Volume-Time Plateau Curves & Catalyst Foils
Deconstructed from 10 past UAT-UK questions (4.44% of all historical Chemistry papers). Students using standard A-Level classroom methods spend an average of 130s on this archetype—blowing past the 90s ESAT budget. Using the 2-line Sub-90 heuristic below compresses solve time to 35s (saving 95s per question).
Historical Frequency
10 Past Qs
4.44% of Chemistry
Classroom Trap Time
130s
+40s over 90s budget
Sub-90 Target Time
35s
Banks +95s on the clock
Dominant UI Format
5-Option A–E
Maths 1 Skill: M4.14
Card 1 & Card 2 Preview: The Classroom Time Trap vs. Sub-90 2-Line Rule
Excerpted from our interactive 6-Step Topic Lesson for ARCH-C-09.
CARD 1 OF 6 • THE CLASSROOM TIME TRAP (130s)
Why Students Bleed Time:
The instantaneous rate of reaction at is the gradient of the tangent to the volume-time curve at : (~80s).
In 10 past UAT-UK questions (4.44% of Chemistry), candidates lose 95s by a catalyst provides an alternative pathway with lower e_a, increasing initial gradient without changing δh or final yield. Instead, apply C10 with Maths 1 skill M4.14.
CARD 2 OF 6 • THE 2-LINE SUB-90 HEURISTIC (<35s)
Line 1 (Tangent Gradient): .
Line 2 (Divide): (15s).
Sanity & Limit Check: Verify units/signs against
multi_statement_linchpin_foil (Statement claiming a catalyst increases the final volume of gas / equilibrium yield or alters ΔH) and factor_of_two_or_stoichiometry_trap (Doubling final gas volume plateau when excess acid concentration is doubled (while solid Mg/CaCO3 is limiting)).Examiner Distractor Blueprint for ARCH-C-09
FOIL #1multi_statement_linchpin_foil
Statement claiming a catalyst increases the final volume of gas / equilibrium yield or alters ΔH
A catalyst provides an alternative pathway with lower E_a, increasing initial gradient without changing ΔH or final yield.
FOIL #2factor_of_two_or_stoichiometry_trap
Doubling final gas volume plateau when excess acid concentration is doubled (while solid Mg/CaCO3 is limiting)
Failing to check which reactant is limiting: final plateau height depends strictly on moles of the limiting reactant.
FOIL #3subsystem_isolation_trap
Halving acid concentration while doubling acid volume and assuming final gas volume halves
Since moles n = (c/2)*(2V) = cV is unchanged, initial slope halves but final plateau height stays identical!
FOIL #4sign_or_direction_flip
Saying temperature increase increases collision frequency as the primary driver rather than the exponential fraction of particles with E >= E_a
Confusing minor collision frequency rise with the major Boltzmann factor E >= E_a.
Try 1 Live Sample Question Under the 90-Second Stopwatch
Press W to open the 2-line dry-wipe scratchpad, select A–E, and lock in to reveal the Dual-View solution.
sub90 ESATARCH-C-09: Reaction Rate Tangent Gradients, Volume-Time Plateau Curves & Catalyst Foils (Sample)Chemistry
00:00.0
SUB-90 ZONE (<35S)
0.0s35s Sub-9090s ESAT Budget150s Classroom
Right-click any option to cross out • Keys
A–E + EnterQuestion 1 of 1 • 90s Target
Ready to Start Question 1?
The question stem, diagram, and answer options are hidden behind this pre-start gate. When you click below, the question will reveal and your 90-second split stopwatch will immediately begin ticking.
Chemistry•ARCH-C-09•Standard 5-Option
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