Question

Calculate the number of moles in 2.5 grams of potassium chloride. Show all the steps.

Answer 1

3.4 X 10^-2 because you start your equation with 2.5g in your (what we call train tracks). Then you have to find the GFM (gram formula mass) of KCl (potassium chloride). You find this by adding the average atomic mass of each element. Potassium's is 39.10 and Chlorine's is 35.45 which gives you a total of 74.55 grams per mol. so now that you have found the GFM you plug that number into the diagonal bottom in order to cancel the gram units. Then you would place 1 mol KCl on top because that is the unit you want. Finally you will divide your original 2.5 by the GFM of 74.55 to get an answer of 0.033534 mol KCl... but since sig figs matter your final  answer will be 3.4 X 10^-2