SCH3U
(4.4) Calculations Involving the Mole
Mole to Mass Conversions
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when substances react, they do so in simple ratios of moles. However, in the lab, balances
give readings in grams.
this is one of the many reasons why we need to understand how to convert grams to moles
and moles to grams
Converting moles to mass
Aluminum is often used for the structure of light-weight bicycle frames. How many grams of
Al are in 3.00 moles of Al?
3.00 moles Al = ? g Al
(to convert between mass and moles or vice versa, you need the molar mass)
Converting mass to moles
The artificial sweetener aspartame (Nutra-Sweet), formula C14H18N2O5, is used to sweeten
diet foods, coffee and soft drinks. How many moles of aspartame are present in 225 g of
aspartame?
The mathematical equations:
moles (n) =
mass (m)
molar mass (M)
mass(m) = moles(n) x molar mass (M)
Converting moles to # of particles
How many molecules are in 3.50 mol of table sugar, sucrose?
How many molecules are present in 2.0 mol of carbon dioxide? How many atoms are present?
How many moles are in 2.40 X 1023 formula units of table salt, NaCl?
The mathematical equations:
moles (n) = # of particles (N)
Avogadro’s # (NA)
# of particles (N) = moles(n) x Avogadro’s # (NA)
Challenge: A multistep problem
What is the mass (in grams) of 1.20 X 1024 molecules of glucose (C6H12O6)?
A Summary
mass (g)
molar mass
moles (mol)
Everything must go through Moles!!!
Avogadro’s number
# particles