Numbers, signs and units in text

In the results section of my text I have to write sentences that more or less go like this:

"(…) the values are in a range of -5 – -2 kcal/mol (…)"

I wanted to:

1. Make some visual difference between hyphen and a minus sign, so it won’t look bad in the text.
2. Prevent Latex from making a line break between the numbers or units.

My solution to this was to wrap each number in $…$, and to wrap the whole expression in mbox{…} like this:

"(...) the values are in a range of mbox{$-5$ - $-2$ kcal/mol} (...)"

It more or less works, but I am not sure if this is the correct and proper way to handle such thing. Are there any packages dedicated to solving this?