What are the typical conservation laws, and how do they apply to everyday life?

1 Answer
Aug 29, 2015

How about conservation of matter? Every chemical reaction conserves matter. We might also add conservation of energy.


If I bake a cake, and use 1 kg of ingredients, at most the baked cake will have a mass of 1 kg. Of course, the cake will mass less than 1 kg, because I will not be able to scrape all the cake batter out of the basin into the baking tin. But even if I did manage to do this, the cake will mass less than 1 kg, because I have likely added raising agents such as baking powder, which will transform into gaseous carbon dioxide (and be lost) during baking.

Continuing on this theme, if I'm worried about getting too fat after eating this cake, I would have to exercise vigorously to use up the calorific content of the cake (the which I could certainly quantify).

Likewise, if I fill my car up with 10 litres of gasoline, if I drive for 100 km or so, the car will lose this mass of gasoline (5-6 kg whatever it is). This mass will be lost to the atmosphere as carbon dioxide and water (of course the oxygen that combusts the gasoline comes from the atmosphere, but this is also quantitatively transformed). The energy content of the #C-H# bonds (as they react with oxygen) has been used to propel the car, which again is something that I could quantitatively measure.