[anita1612]

So a few days ago i did a lab where i to use a Styrofoam cup and calculation how much energy transferred from the ice into the water. Well when i did my calculation i had a 24% error. My chemistry said that in prior years he had used double layer Styrofoam. Would this make a difference to my ΔH?

[Amu-ka]

What was the main cause of your error? Loosing energy to the surroundings, or measurement errors? If it was the first one, using better insulation or closing the cup could make a difference. But maybe some energy was used for cooling the cup, not water? Have you taken that into account?

+ my knowledge of physics is not perfect, but I would say that it was the energy from water used for warming up ice, not the other way round. Though it would mean that energy was taken from the cup... or whatever, 24% error is not that terrible, I had some as high as 60% -.-

[jtlu]

Styrofoam is a pretty good insulator, I doubt it would have mattered. Compare the percent error to propagated random error. If the percent error is less than the percent uncertainty, there is no problem because your measuring equipment is merely not precise enough.