SAT II Chemistry : Enthalpy

Study concepts, example questions & explanations for SAT II Chemistry

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Example Questions

Example Question #1 : Thermochemistry And Kinetics

Suppose that 1.5 moles of potassium reacts completely with an excess of chlorine gas. What is the enthalpy change of the reaction?

Possible Answers:

Correct answer:


First, note that heat is a product of the reaction. This means that the reaction releases heat and is exothermic, so the enthalpy change must be negative. Next, consider that 2 moles of sodium would react to produce 640 kJ. Thus, 1.5 moles of sodium would react to produce


Hence, the enthalpy change is .

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