Expressing amounts of energy in different energy units is necessary to solve many chemistry problems. For practice, complete the following table. FILL IN THE BLANKS PLEASE.

Question

The Joule (J) is the SI unit of energy. 1 calorie (cal) = 4.184 J

J cal kJ
695 ___ ___



___ 132 ___



___ ___ 0.478

Answer 1

1 cal = 4.184 J
1000 J = 1 kJ.

The way you do these is to make the units convert from what you have to what you want. I wrote the factors above. Here is how you do the first one. I'll leave the others for you.

The factor for calories to J is one of these two; i.e., 1 cal/4.184 J OR 4.184 J/1 cal. You want to convert 695 cal to J.
695 cal x factor = ? J and you must plug in the factor. It MUST be one of the two above. Let's try one factor, then the other.
695 cal x (1 cal/4.184 J) = ? and
695 cal x (4.184 J/1 cal) = ?
ONE of those MUST be right. Which one. Take them 1 at a time. Only look at the units.
The first one is cal x cal/J which gives (cal^2/J). You were looking for J. Right? So this one can't be right. Look at the second.
Again, look only at the units.
The second one is cal x J/cal. Notice that cal cancels and J doesn't so that's the one to use because you want J. Therefore,
695 cal x (4.184 J/cal) = ? J and that just leaves the calculation. If you want to put that into a formula, it is this.
(#+unit you have) x (unit you want/unit you have) = #+unit you want to convert to.
I'll be glad to check your work on the others.