All topicsWhich reaction has ΔS° > 0?2025 national · question 2311%The natural logarithm of the Ka of NH₄+ is plotted below as a function of the reciprocal of the absolute tempe2018 national · question 2315%A system confined in a rigid, well-insulated container undergoes a spontaneous change. What statement about th2019 national · question 2223%
Thermodynamics
This is block 4 of 10, questions 19–24 on both the local section exam and national Part I. Across the 40 national questions where ACS published item statistics, qualifiers answered 52% correctly, which makes it the eighth hardest of the 10.
What it covers
enthalpyHess's lawcalorimetryentropyGibbs free energybond energiesspontaneity
Where qualifiers lose points
% who got it rightThese are the thermodynamics questions the fewest national qualifiers answered correctly. If you can do these, the block is not your problem.
Every question is from a published past exam and carries its source. Practice adapts to what you miss, and anything you get wrong comes back on a spaced schedule. No account needed. See the other nine blocks.