2KCIO3 > 2KCl + 3O2
How many grams of potassium chloride are produced if 25g of potassium chlorate decompose?
So you are trying to find grams of KCl. So start off with the given (25g) and do dimensional analysis to
get grams of KCl. So go from 25g of KCIO to the molar mass, which is 122 grams, which gives you 1 mole of KCIO. For every
2 moles of KCIO (the coefficient "2" in front of KCIO is the # of moles), there are 2 moles of KCl. So then find the molar
mass of 1 mole KCl, ( 74g), and multiply it out! See if you got the right answer (see MassMass Problem 1 Picture)
MoleMole
Zn + 2HCl > ZnCl2 + H2
How many moles of hydrogen are produced from the reaction of three moles of zinc with an excess
of hydrochloric acid?
The molemole problems are short and sweet. You start off with the given again ( 3 moles of Zn). Since you
are trying to find moles of H2, you go from moles of Zn to moles of H2. So for every 1 mole of Zn, you have 1 mole of H2.
Now just multiply it out!



More Problems:
MassMass
1. N2 + 3H2 > 2NH3 How many grams of hydrogen are necessary to react completely
with 50 g of nitrogen?
2. 2AgNO3 = BaCl2 > 2AgCl + Ba(NO3)2 How many grams of silver chloride are
produced from 5 g of silver nitrate reacting with an excess of barium chloride?
MoleMole
1. N2 + 3H2 > 2NH3 How many moles of hydrogen are needed to completely
react with two moles of nitrogen?
2. C3H8 + 5O2 > 3CO2 + 4H2O How many moles of oxygen are necessary to react completely
with four moles of propane (C3H8) ?
Answers:
MassMass
1. 10.7 g H2
2. 4.2 g Ag
MoleMole
1. 6 moles of H2
2. 20 moles of O2




