5.25 calories are absorbed by an iron nail. How many joules is this?

1 Answer
Truong-Son N.
Aug 4, 2017

By definition, #"1 cal"# is the approximate amount of energy needed to raise the temperature of #"1 g"# of water by #1^@ "C"# at #"1 atm"#.

In thermochemistry, this is known to be equal to #"4.184 J"# at #25^@ "C"#. Therefore...

#5.25 cancel"cal" xx "4.184 J"/cancel"cal" = "21.97 J"#

Or to three sig figs, #~~# #ulcolor(blue)"22.0 J"#.

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