Name ____________________
Period ______
Recipes in Chemistry
The “recipe” for making ammonia is: N2 + 3H2  2NH3
There are 3 different ratios in this recipe, using the coefficients:
 1N2 : 3H2 or 1N2
3H2
 1N2 : 2NH3 or 1N2
2NH3
 3H2 : 2NH3 or 3H2
2NH3
These ratios are called molar ratios.
In mole to mole problems, one might be asked how many moles of one
chemical are needed to react with/or produce another chemical.
For instance, how many moles of nitrogen would be needed to react with 9
moles of hydrogen?
9 mol H2 x 1 mol N2 = 3 mol N2
1
3 mol H2
How many moles of ammonia would be produced from 16 moles of nitrogen and
excess hydrogen (When it says excess something, that means you don’t need
to worry about it)?
How many moles of hydrogen would be needed to produce 17 moles of
ammonia?
How many moles of nitrogen would be needed to react with 0.6 moles of
hydrogen to produce ammonia?
Name ____________________
Period ______
The “recipe” for making ammonia is: N2 + 3H2  2NH3
There are 3 different ratios in this recipe, using the coefficients:
 1N2 : 3H2 or 1N2
3H2
 1N2 : 2NH3 or 1N2
2NH3
 3H2 : 2NH3 or 3H2
2NH3
The molar masses of the three substances are:
 N2
 H2
 NH3
In mass to mole problems, a mass is given which must be changed into
moles and then changed to the moles of the other substance.
For instance, how many moles of nitrogen would react with 6 grams of hydrogen
gas?
6 grams H2 x 1 mol H2 x 1 mol N2 = 1 mole N2
1
2 grams H2 3 mol H2
How many moles of hydrogen are needed to produce 85 grams of ammonia?
How many moles of ammonia would be produced from 84 grams of nitrogen
and excess hydrogen?
How many moles of nitrogen would be needed to react with 27 grams of
hydrogen?
Name ____________________
Period ______
The “recipe” for making ammonia is: N2 + 3H2  2NH3
There are 3 different ratios in this recipe, using the coefficients:
 1N2 : 3H2 or 1N2
3H2
 1N2 : 2NH3 or 1N2
2NH3
 3H2 : 2NH3 or 3H2
2NH3
The molar masses of the three substances are:
 N2
 H2
 NH3
In mole to mass problems, a number of moles is given which must be
changed into moles of the other substance and then changed into mass.
For instance, how many grams of nitrogen would react with 6 moles of hydrogen
gas?
6 moles H2 x 1 mol N2 x 28 g N2 = 56 grams N2
1
3 mol H2
1 mol N2
How many grams of hydrogen are needed to produce 5 moles of ammonia?
How many grams of ammonia would be produced from 14 moles of nitrogen
and excess hydrogen?
How many grams of nitrogen would be needed to react with 33 moles of
hydrogen?
Name ____________________
Period ______
The “recipe” for making ammonia is: N2 + 3H2  2NH3
There are 3 different ratios in this recipe, using the coefficients:
 1N2 : 3H2 or 1N2
3H2
 1N2 : 2NH3 or 1N2
2NH3
 3H2 : 2NH3 or 3H2
2NH3
The molar masses of the three substances are:
 N2
 H2
 NH3
In mass to mass problems, a mass is given which must be changed into
moles and then changed to the moles of the other substance, and then
mass.
For instance, how many grams of nitrogen would react with 6 grams of
hydrogen gas?
6 grams H2 x 1 mol H2 x 1 mol N2 x 28 grams N2 = 28 grams N2
1
2 grams H2 3 mol H2 1 mol N2
How many grams of hydrogen are needed to produce 68 grams of ammonia?
How many grams of ammonia would be produced from 128 grams of nitrogen
and excess hydrogen?
How many grams of nitrogen would be needed to react with 21 grams of
hydrogen?