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Experiment 7.3A, B: (P.27 - 30)
Comparing
the energy contents (能量值) of different snacks?
Objective: To
compare the energy contents of cookies and peanuts.
Design
of Experiment: (P.29)
Consider of “3Cs” of a fair test (公平測試)
n
Variable
to be changed: type of snack
n
Variable(s)
to be kept constant保持不變: (Put a “Ö” in the appropriate boxes.)
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Weight of food
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Ö
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Volume of water
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Size of food pieces
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Ö
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Type of boiling tube
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Type of food
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Ö
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Type of burning spoon
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Ö
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Initial temperature of water
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Ö
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Others:
position and
distance of burning food from the boiling tube
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of water
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n What to compare: increase in water temperature per gram of snack
used
2. Set up the apparatus as shown. Measure the
temperature of the water.
The
temperature of the water is _________________oC
6. When
the peanut is completely burnt, measure the highest temperature of the water
reached.
The
highest temperature of the water is _______________oC.
Results:
(P.30)
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Snack
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Weight of snack used (g)
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Initial water temperature (oC)
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Highest water temperature reached in burning (oC)
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Increase in water temperature* (oC)
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Increase in temperature per gram of snack used# (oC
g-1)
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Peanut
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W
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I
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H
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H - I
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(H - I) / W
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Cookies
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w
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i
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h
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h – i
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(h – i) / w
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*Increase in water temperature = Highest water
temperature reached – Initial water temperature
#Increase in temperature per gram of snack used = 
Discussion:
(P.30)
How
can you compare the energy contents of the snacks according to you results?
According to the results, the greater
(greater / smaller) the increase in water temperature per gram of snack burnt,
the higher the energy content of the snack.
Conclusion: (P.30)
The
energy contents of peanut is higher / lower (depends on results) than that of cookies.
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