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Accuracy of Experimental Value

The data book value for methanol is -726 kJmol-1. The experimental value may be less exothermic than expected because less heat is transferred to the water than the reaction releases. The reasons for less heat being transferred are:Some of the heat produced in the reaction is used to heat the beaker and the air surrounding the flames.
There may be incomplete combustion of methanol
Some of the methanol may evaporate
conditions may be non-standard

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Specification: OCR Chemistry A (H032), AS-level, 3.2.1 Enthalpy changes. Topic: Enthalpy.

Key terms in this lesson

Exothermic
Describes a process in which heat energy is transferred from the system to the surroundings, so the enthalpy change is negative.

More in Enthalpy

All 19 lessons in Enthalpy · All OCR AS-level Chemistry topics