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News & Updates
Season announcements, exam guidance, and Team USA results from the U.S. National Chemistry Olympiad.
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USNCO Calorimetry: Define the System Before Assigning the Sign of Heat
In USNCO calorimetry problems, the sign of heat (q) depends entirely on how you define the system. This guide clarifies the boundary between system and surroundings to prevent common sign errors in enthalpy calculations.
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USNCO Equilibrium Approximations: Knowing When the Small-Change Shortcut Fails
A focused guide on when to apply and when to abandon the small-x approximation in USNCO equilibrium problems, featuring worked teaching illustrations and a diagnostic decision table.
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USNCO Redox Balancing: Checking Both Charge and Atom Conservation
A focused guide to the most common USNCO redox balancing mistake: forgetting to verify both charge and atom conservation. Two worked teaching illustrations, one deliberate error, and a diagnostic table to build reliable exam habits.
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USNCO Limiting Reagents: Tracking the Reaction Before Calculating the Yield
A focused guide for USNCO preparation on identifying limiting reagents through stoichiometric tracking, avoiding common calculation pitfalls with worked teaching illustrations.
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USNCO vs CCC: Which Chemistry Competition to Prepare for When You Cannot Do Both
Struggling to choose between USNCO and CCC? This guide clarifies the real differences in format, difficulty, and eligibility to help you pick the right path when time is limited.
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USNCO Past Papers: Requesting Explanations Beyond an Answer Key
A guide to using USNCO past papers effectively, distinguishing between answer keys and detailed explanations, and understanding resource availability.
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USNCO Registration Guide for the 2026-2027 Season
Registration for the 2026-2027 US National Chemistry Olympiad opens on November 1, 2026. This guide clarifies eligibility rules, coordinator communication strategies, and verified student pathways.
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USNCO Laboratory Questions on Paper: Glassware, Separations and Which Way the Error Goes (2026)
USNCO laboratory questions reward decisions more than bench hours: which glassware, which separation, and which way a procedural slip moves your answer.
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Phase Diagrams, Vapour Pressure and Heating Curves: The USNCO Phase-Change Questions, Decoded (2026)
Beyond the gas laws: how to read a phase diagram, use vapour pressure and Clausius-Clapeyron, and keep heating-curve energy books straight for the USNCO.
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USNCO for Chinese Students at US High Schools: The Local Exam Route, Step by Step (2026-27)
Enrolled at a US high school without US citizenship or a green card? ACS lets you sit the USNCO Local Section Exam, not the National. How to enter and report it.