Download 12.2 Chemical Calculations

By: Rita Akhian
Q. 4 technology project
Chemistry
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A mole ratio is a conversion factor derived from
the coefficients of a balanced chemical equation
interpreted in terms of moles.
Mole ratios are used to convert between moles of
reactants and moles of products.
For Example:
N₂(g) + 3H₂(g)  2NH₃(g)
1 mol N₂/3 mol H₂
2 mol NH₃/1 mol N₂
3 mol H₂/2 mol NH₃
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In a mole-mole calculation, the unknown can
be either a reactant or a product.
In mass-mass calculations, the amount of a
substance is determined by measuring its
mass in grams. The mass can later be
converted to moles by using the molar mass.
Then use the molar mass to calculate the
number of moles in that mass.
Moles to mass (mass-mass, mass-mole, and
mole-mass)
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The given quantity is first converted to moles.
Then the mole ratio from the balanced
equation is used to calculate the number of
moles of the wanted substance. The moles
are later converted to any other unit of
measurement related to the unit mole, in the
required problem.
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The given quantity can be
expressed in numbers of
representative particles,
units of mass, or volume of
gases at STP.
Mass-mass
Mass-moles
Mass-volume
Volume-volume
Particle-mass
Etc.
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Practice problem #17 pg 365
The equation for the combustion of carbon
monoxide is 2CO(g) + O₂(g)  2CO₂(g). How many
liters of oxygen are required to burn 3.86 L of
carbon monoxide?
3.86L CO x 1 mol CO x 1 mol O₂ x 22.4L O₂ =
22.4L CO
1 mol CO
1 mol O₂
3.86 L O₂