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Heat Related Problems

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Hi, I need some assistance with the following questions:
1) You have two pieces of Al metal - one is a thin piece of Al foil, and the other is a thick block. Both have the same length and width. Which will absorb more heat when set on a hotplate for the same period of time to raise the temperature 5 degrees?

a) Block
b) Foil
c) The heat capacity is the same, so they will absorb the same amount of heat.
d) Heat would actually be released from both the block and foil.

2) Which is true?

a) Delta Hrx is usually measured and reported in KJ/mol.
b) An endothermic reaction gives a +Hrx.
c) The enthalpy of formation of liquid nitrogen is 0 KJ.
d) A phase change from solid to liquid results in a -q value.

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Solution Preview

1. The difference between the foil and the block is the thickness. The thicker the metal, the more mass it has, and therefore will require more heat to raise the temperature by 5 degrees, which is the question. The foil will get hotter if you add the same amount of heat, but the question ...

Solution Summary

The following solution provides the guidance necessary to assist a student in solving these two chemistry-based problems. All concepts are explained in a detailed and understandable manner.