Cons of using polystyrene cup in experiment..?

Ok I have to explain the limitations of using a polystyrene cup in an experiment. In the experiment: the cup held copper sulphate solution which reacted with zinc, and produced heat energy.

I'm not sure why this would limit my results? I'm sure it has something to do with the heat produced was conducted, which is inaccurate because -----

The improvement would probably be to use a metal cup which absorbs more heat energy.
Thanks so much if you help :smile:

Reply 1

pineneedles

14

Original post by Ella_08

Ok I have to explain the limitations of using a polystyrene cup in an experiment. In the experiment: the cup held copper sulphate solution which reacted with zinc, and produced heat energy.

I'm not sure why this would limit my results? I'm sure it has something to do with the heat produced was conducted, which is inaccurate because -----

The improvement would probably be to use a metal cup which absorbs more heat energy.
Thanks so much if you help :smile:

You would use a polystyrene cup rather than a metal cup as the polystyrene is insulating and reduces heat loss, while the metal cup would conduct the heat to the surroundings.
Heat loss limits the accuracy of the results because in doing the calculations for this experiment, you assume that:
The heat given out by the reaction = the heat raising the temperature of the solution.
Can you see that if you don't ensure that as much of the heat given from the reaction is insulated in the solution as possible, your answer won't be as accurate?

Reply 2

username1454260

OP

17

Original post by pineneedles

You would use a polystyrene cup rather than a metal cup as the polystyrene is insulating and reduces heat loss, while the metal cup would conduct the heat to the surroundings.
Heat loss limits the accuracy of the results because in doing the calculations for this experiment, you assume that:
The heat given out by the reaction = the heat raising the temperature of the solution.
Can you see that if you don't ensure that as much of the heat given from the reaction is insulated in the solution as possible, your answer won't be as accurate?

Yes I understand your explanation, that's such a good point and I'll use it in my evaluation. However, I do have to explain limitations in the plastic cup. Or I may discuss the limitations in a measuring cylinder as well (i.e. imprecise scale contributes to human error in capacity of solution readings)

Thank you (: ur a great help

Reply 3

pineneedles

14

Original post by Ella_08

Yes I understand your explanation, that's such a good point and I'll use it in my evaluation. However, I do have to explain limitations in the plastic cup. Or I may discuss the limitations in a measuring cylinder as well (i.e. imprecise scale contributes to human error in capacity of solution readings)

Thank you (: ur a great help

No problem. Just want to ask : are you answering a specific question or evaluating the experiment thoroughly? and are you studying GCSE or AS level?Other limitations of the cup itself could be that, if you used an open polystyrene cup there will obviously be heat loss from the top of the cup. You might also mention that although the polystyrene cup is better insulated than the metal cup, there is still some heat loss to the surroundings?It'd be good to talk about measuring limitations, as you said, possible improvements for this could be to measure greater masses and volumes, as percentage error on larger values is less significant, and of course using more precise equipment. Incomplete combustion is also a factor!