01/06/11

What is the Molar Mass of the following:•Calcium•Sodium•Oxygen

TURN AND TALK Chat with your neighbors about the

following questions?

What is MOLAR MASS?

What is the Molar Mass of the following simple compounds:

•Sodium Chloride•Lithium Bromide•Magnesium Oxide

Molar Mass of a Compound

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?

Practice Problem Extension

Percent CompositionChemical 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 total molar mass of the compound and the molar mass of the element/compound that you are finding the percent composition

Percent CompositionChemical CompoundsPercent 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 total molar mass of the compound and the molar mass of the element/compound that you are finding the percent composition

Then divide the molar mass of unknown percentage by the total molar mass and multiply by 100 to get your answer

Practice: Percent Composition of sodium in sodium chloride

Molar Mass of Na= Cl=Molar Mass NaCl =

%Na =

Percent CompositionChemical Compounds

Practice: Percent Composition of magnesium in magnesium oxide

Molar Mass of Mg= O=Molar Mass MgO =

%Mg =

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?

Practice Problem Extension