The actual enthalpy of the magnesium flare reaction is –603 kJ/mol. Your experimental value was likely different. Check all that apply.

Each factor could make the experimental heat measurement differ from the actual reaction enthalpy. The cup can absorb heat, and heat can escape through a lid that does not seal perfectly, so less heat may be measured in the solution. An improperly positioned or inaccurate thermometer, or difficulty catching the maximum temperature, can also produce an incorrect temperature change and therefore an inaccurate enthalpy value.

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