R1.1 Measuring enthalpy changesIB Chemistry HL: Flashcards

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Difference between heat and temperature?

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Difference between heat and temperature?: Temperature measures the average kinetic energy of particles; heat is energy transferred because of a temperature difference.
Sign of ΔH for an exothermic reaction?: Negative.
What happens to the temperature of the surroundings in an endothermic reaction?: It falls.
Which is more stable in an exothermic reaction: reactants or products?: The products (lower enthalpy).
Describe an exothermic energy profile.: Products below reactants, ΔH arrow downward, activation energy hump above reactants.
In an endothermic profile, how does Ea compare with ΔH?: Ea is larger than ΔH.
Define standard enthalpy change, ΔH⦵.: Heat transferred at constant pressure under standard conditions and states.
Standard pressure?: 100 kPa.
Equation linking heat and temperature change?: Q = mcΔT.
How is ΔH obtained from Q?: ΔH = −Q ÷ n (in kJ mol⁻¹).
Which mass goes into Q = mcΔT for a solution reaction?: The mass of the whole solution being heated (volume × 1.00 g cm⁻³).
Why are calorimetry results usually less exothermic than data booklet values?: Heat is lost to the surroundings and absorbed by the apparatus.
Is dissolving ammonium nitrate endo- or exothermic?: Endothermic: the temperature falls.