The molar mass of sodium chloride is 58 g/mol. How many grams of sodium chloride are in 0.5 mol of sodium chloride?

The answer is 29 grams.

NaCl n(NaCl) = 0,5 mol M(NaCl) = 58 g/mol

This is incredibly easy example. its actually perfect to demonstrate a little trick that can help you tremendously in the future.

So, you are supposed to calculate m(NaCl) = the weight of NaCl. And you have some quantities.

If you look at them again, and their units , even if you didnt know the equation, you CAN figure it out thanks to the Units . One unit says grams divided by mols . Your other unit is in mols . Take the g/mol and time it with mols. This will remove the mols in the first example, leaving you with just grams. Tada! You figured out the equation needed for the example.

Again: ##g/(mol) * mol = g##

And that is why you should always write down your Units. It will help you figure out if your equation is correct. Its invaluable help in chemistry and physics.

This means your equation is: ##m(NaCl) = M(NaCl) * n##

##m(NaCl) = 58 * 0,5= 29g##