The Mole Unit 5. Formula Mass Formula mass - also called: formula massmolecular mass molecular massformula weight formula weightmolecular weight molecular.

The MoleUnit 5

Formula Mass

• Formula mass - also called:

formula mass molecular mass

molecular mass formula weight

formula weight molecular weight molecular weight molar mass

molar weight the mass of one mole of a compound,

atom or ion. (units: _g_ ) mol

Formula Mass:Example: Calculate the formula mass of the

following:

I Do: carbon tetrachloride Formula: CCl4

1 C: 12.011 g/mol4 Cl: 4 x 35.45 g/mol = 141.8 g/mol

Total mass: 153.81 g/mol

Formula MassExample: Find the formula mass of each of the

following:

We Do: arsenic trichloride: Formula: AsCl31 As: 74.922 g/mol3 Cl: 3 x 35.45 g/mol = 106.35 g/mol


Formula MassExample: Find the formula mass of each of the

following:

You Do: potassium sulfide Formula: K2S

2 K: 2 x 39.098 g/mol = 78.196 g/mol1 S: 32.066 g/mol


Measuring MatterThere are three ways to measure

matter: 1. By counting representative

particles: atoms – element

molecules- covalent compound

formula units- ionic compound

ions – anything with a charge

.

Al, Na, S, etc

PCl3,O2, CO2

AlCl3,K2O, Ba3P2

PO32-,K1+

2. By mass - in grams

3. By volume - in liters for gases (at STP)

Measuring Matter

1 mole of a compound = formula mass (in grams)1 mole of a compound = 6.02 x 1023 representative particles 1 mole of a gas (STP) = 22.4 liters

The mole is the link between grams, the number of representative particles and liters!

Remember: There are 4 different types of Representative ParticlesAtomsFormula unitsMoleculesIons

Identify the type of Representative Particle

• NaCl

• F2

• NH4+1

• CS2

• H2O

• Be

• CsF

Formula Units

Molecules

Ions

Molecules

Molecules

Atoms

Formula Units

Mole Road Map

Mole Practice: One Step Conversions: Remember to show all work using dimensional analysis.

I Do: How many moles are present in a tank of gas that contains 55.60 Liters?

Conversion Factors:

1 mole = formula mass 1 mole or g g 1 mole

1 mole = 6.022 x 1023 1 mole or 6.022 x 1023

particles 6.022 x 1023 1 mole

1 mole = 22.4 Liters gas 1 mole or 22.4 L 22.4 L 1 mole

55.60 Liters = 2.48 moles of gas

Make sure to round the finalAnswer to the 100th place.Only the final answer!


We Do: How many moles are in 18.0 grams of sugar (C6H12O6)? Conversion Factors:


1 mole = 6.022 x 1023 1 mole or 6.022 x 1023



18.0 g C6H12O6


Add Masses of 6C + 12H + 6OYou must use all theNumbers from the Periodic Table


You Do: What is the mass in grams of 4.50 moles of barium sulfide? Conversion Factors:


1 mole = 6.022 x 1023 1 mole or 6.022 x 1023



4.50 mol BaS


Add Masses of 1 Ba + 1 SYou must use all theNumbers from the Periodic Table

Two and Three Step Conversions

I Do: What is the mass in grams of 5.02 x 1024 formula units of potassium phosphate? Conversion Factors:


1 mole = 6.022 x 1023 1 mole or 6.022 x 1023



5.02x1024 Formula units K3PO4

= 1117.98 g K3PO4

Two and Three Step ConversionsWe Do: How many molecules are in 198.5

grams of sodium chloride? Conversion Factors:


1 mole = 6.022 x 1023 1 mole or 6.022 x 1023



198.5g NaCl= 2.04x1024 Formula Units NaCl

Two and Three Step Conversions

You Do: How many Liters of gas is 3.21 x 1024 molecules of carbon monoxide?

Conversion Factors:


1 mole = 6.022 x 1023 1 mole or 6.022 x 1023



3.21x1024 Molecules CO = 119.44 L CO

The Mole Unit 5. Formula Mass Formula mass - also called: formula massmolecular mass molecular massformula weight formula weightmolecular weight molecular.

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