Enthalpy - SAT Subject Test in Chemistry
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Question
Suppose that 1.5 moles of potassium reacts completely with an excess of chlorine gas. What is the enthalpy change of the reaction?
Suppose that 1.5 moles of potassium reacts completely with an excess of chlorine gas. What is the enthalpy change of the reaction?
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 
.
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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