01/06/11
TURN AND TALK
Chat with your neighbors about the
following questions?
What is MOLAR MASS?
What is the Molar Mass of the following:
•Calcium
•Sodium
•Oxygen
Molar Mass of a Compound
What is the Molar Mass of the following simple
compounds:
•Sodium Chloride
•Lithium Bromide
•Magnesium Oxide
Practice Problem Extension
Carbon dioxide – write the formula, calculate
molar mass.
Q1. How many moles of carbon dioxide are in
120.g?
Think about how you convert mass to
moles…
Practice Problem Extension
Ammonium sulfide – write the formula, calculate
molar mass
Q2. How many moles of ammonium sulfide are
in 2.50g?
Percent Composition
Chemical Compounds
Percent composition refers to the percent by
mass of an element or compound within a
larger compound.
To find it, you need the total molar mass of the
compound.
And the molar mass of the element (part)
that you are finding the percent
composition
Percent composition refers to the
percent by mass of an element or
compound within a larger compound.
To find it, you need the total molar
mass of the compound.
And the molar mass of the element
(part) that you are finding the percent
composition
Then divide the molar mass of
unknown part by the total molar mass
and multiply by 100 to get your answer
Percent Composition
Chemical Compounds
Practice: Percent Composition of
sodium in sodium chloride
Molar Mass of Na=
Molar Mass NaCl =
%Na =
Cl=
Percent Composition
Chemical Compounds
Practice: Percent Composition of magnesium in magnesium oxide
Molar Mass of Mg=
Molar Mass MgO =
%Mg =
O=
Practice Problem Extension
Dinitrogen pentoxide – write the formula,
calculate molar mass
Q4. What is the percent composition of nitrogen
in dinitrogen pentoxide?
Practice Problem Extension
Calcium acetate – write the formula, calculate
molar mass
Q5. What is the percent composition of calcium
in calcium acetate?
Can you figure out how many grams of calcium
are in 50g of calcium acetate?