Question

the actual enthalpy of the magnesium flare reaction is -603 kj/mol. your experimental value was likely different. choose three correct answers. the plastic coffee cup lid did not have allow any heat to escape. the coffee cup calorimeter may have absorbed some heat. the thermometer did not measure the temperature of the solution properly. reading the maximum temperature values from the thermometer could be challenging.

Explanation:

The plastic coffee - cup lid not allowing heat to escape would lead to a more accurate result, not an inaccurate one. The coffee - cup calorimeter absorbing heat, the thermometer not measuring the temperature properly, and difficulty in reading the maximum temperature values from the thermometer can all cause experimental values to differ from the actual enthalpy value.

Answer:

The coffee cup calorimeter may have absorbed some heat.
The thermometer did not measure the temperature of the solution properly.
Reading the maximum temperature values from the thermometer could be challenging.