Question

1. Describe the parts of a coffee-cup calorimeter. In your description, specify the use of each part.
2. Outline how you would use a calorimeter to determine the enthalpy of fusion of ice.
3. Suppose the enthalpy of fusion of ice determined from your experiment is lower than the accepted value. List three possible causes of the difference in value. Explain how each cause affects the calculated value of Hf.

Answer 1

Want to start with #1? @Hoslos

Answer 2

The coffee cup is very good when it comes to calorimetry, because the doule insulating part of the cup has a sepecific heat capacity similar to that of water and the solution contatent stays inside the cup. The heat released and absorbed by the reaction is almost perfectly absorbed by the cup and the measurements of standard enthalpy change are very accurate.

Answer 3

Thanks! Now #2

Answer 4

In that case, if the caloreter is very effective, then heat lost by water is heat gained by ice and the formula applies: Q = mass of water * specific heat capacity of water * temperature change of water.

Answer 5

ok so thats the answer for #2?

Answer 6

Yes.

Answer 7

OK thanks! Now just #3 ! :)

Answer 8

There must have been a bit lot of ventilation in the room, providing large wind force, which would force warm particles to evaporate faster, giving less heat calculated/measured value. The experimenter might have stirred the solution forcefully, releasing some of the solution, also leaving with some heat. Another possibility was that a misreading on the thermometer might occur, if the experimenter's eye is not perpendicular to the scale reading.

Answer 9

Thank you sooo much! You're so helpful! :)

Answer 10

No problem. See you.