What is a MOLE?

There are 12 items in a dozen

There are 144 items in a gross of any substance

There are 6.02 x atoms or molecules in a mole of any substance I’m going to need a bigger shovel!

6.02 x = 602, 000,000,000,000,000,000,000

A mole of standard soft drink cans would cover the surface of the Earth to a depth of over 200 miles.

If you had a mole of unpopped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of over 9 miles.

Molar mass is the weight of one mole (or 6.02 x molecules) of any chemical compounds.

Molar Masses Water’s molar mass is 18 grams PVC’s molar mass is 150,000 grams

How can I find the molar mass of an element? Use the element’s mass on the periodic table

Example: What is the molar mass of Carbon? Carbon’s atomic mass is……12.01 Therefore, Carbon’s molar mass is… g

Example: What is the molar mass of Magnesium? Magnesium’s atomic mass is……24.31 Therefore, Magnesium’s molar mass is… g

Example: What is the molar mass of Krypton? Krypton’s atomic mass is……83.80 Therefore, Krypton’s molar mass is… g

Practice Time!

ElementMolar MassElementMolar mass Helium (He)Argon (Ar) Chlorine (Cl) Neon (Ne) Sodium (Na)Phosphorus (P)

Now, let’s kick it up a notch!

To calculate the molar mass of a compounds First you find the molar mass of the parts of the compound and then you add. If there are more than one of a type of atom in the compound, you multiply the number of atoms time the molar mass of the one atom, and then add all parts together.

What’s the molar mass of a compound like NaCl? Molar mass of Na =22.99 Molar mass of Cl =35.45 So, the Molar mass of NaCl = g

What’s the molar mass of C 6 H 12 O 6 ? 6 x = x = = g Molar mass of C 6 = Molar mass of H 12 = 6 x 16.00= 96 Molar mass of O 6 = So, the Molar mass of C 6 H 12 O 6 =

Practice Time!

Compo und Molar MassCompo und Molar mass Carbon dioxide (CO 2 ) Ammo nia (NH 3 ) Ethanol (C 2 H 6 O ) Sulfuri c acid (H 2 SO 4 )

Calculate the Molar Mass: Ca(NO 3 ) 2

Percent Composition A percent is a ratio. Sometimes we want to know how much of an element is in the compound.

Steps to determine percent composition 1.Calculate the molar mass from the formula. 2. Determine how many grams the atom of interest contributes to the compound 3.Divide the mass of the atom by the molar mass and multiply by 100 to get a percentage. % Composition = Mass of the element in cmpd x 100 Molar Mass of cmpd

Example: Find the % of Na and Cl in NaCl Sodium Chloride, NaCl Na = 22.99g Cl = 35.45g Molar Mass = 58.44g %Na = x =39.34 % Na %Cl = x = 60.7% Cl

Find the % of each element in Na 2 SO 4

Give the % composition of all the elements in Magnesium sulfiteFormula

Relating Moles & Mass

What you already know…. How big is a mole? 6.02 x atoms or molecules How do you determine molar mass of an atom? It’s the same as atomic mass. How do you determine molar mass of a molecule? It’s the same as the sum of the atomic masses of the parts.

Chemist use moles to understand relationships between reactants and products. In the lab we don’t have a balance that measures moles. We must relate grams to the number of moles.

What you don’t know How many moles are in this glass of water?

What else you don’t know Can you add 3.25 moles of water to the beaker?

These two questions can be solved by using c o n v e R s i  n s !

A Conversion is just a math equation in which you 1. START with the data and units they give you in the problem, and then 2. MULTIPLY by CONVERSION FACTORS until you have the right units at the end.

What’s a Conversion Factor? It’s a FRACTION in which the TOP number and BOTTOM number mean the same thing but have different units. 12 eggs 1 dozen 1 week 7 days 3 feet 1 yard 6 points 1 touchdown 100 yards 1 football field 1 cup 8 ounces Write 3 of your own!

Mole Conversion Molar Mass or 1 Mole 1 MoleMolar Mass

How do you know which part to put on top and which part to put on bottom? Because 12 eggs 1 dozen Is the same thing as 1 dozen 12 eggs How do you know which one to use?

RULE!!!! Use the conversion factor with the UNITS of the info they give you in the problem on the BOTTOM and the UNITS of what you’re LOOKING FOR on the TOP!!

So, if they tell you there are 8 dozen and ask you how many eggs there are: START with what they give you 8 dozen MULTIPLY X By a conversion factor that connects eggs to dozens. How many eggs in ONE dozen? 12 eggs 1 dozen NOTE: The “dozen” in the first number and the “dozen” in the bottom of the conversion factor will cancel each other out, leaving eggs!!! = 96 eggs

For example: How many grams are in 3 moles of Carbon? START with what they give you 3 moles MULTIPLY X By a conversion factor that connects moles to grams. How many grams in ONE mole of hydrogen? grams 1 mole C NOTE: The moles in the first number and the moles in the bottom of the conversion factor will cancel each other out, leaving grams!!! =36.00 g

Another example, this time a little trickier: How many grams are in 5 moles of carbon dioxide (CO 2 )? START with what they give you 5 moles CO 2 MULTIPLY X By a conversion factor that connects moles to grams. How many grams in ONE mole of carbon dioxide? grams 1 mole CO 2 NOTE: The moles in the first number and the moles in the bottom of the conversion factor will cancel each other out, leaving grams!!! = g

Steps to conversions 1.Write the given. 2.Draw a “times and a line” 3.Write the units you were given on the bottom 4.Write the units you want on top 5.Fill in the conversion factor (remember 1 is always with the mole) 6.Multiply all the numbers on the top and divide it by the numbers on the bottom.

Practice Time!

How many grams are there in 350 moles of iron (Fe)? How many grams are there in 3 moles of Lithium (Li)? How many grams are there in 46 moles of water (H 2 O)? How many grams are there in 12.7 moles of magnesium chloride (MgCl 2 )? A chemist needs 12.5 moles of sulfuric acid (H 2 SO 4 ). How many grams does he need?

How many grams are there in 350 moles of iron (Fe)? g How many grams are there in 3 moles of Lithium (Li)? g How many grams are there in 46 moles of water (H 2 O)? g How many grams are there in 12.7 moles of magnesium chloride (MgCl 2 )? g A chemist needs 12.5 moles of sulfuric acid (H 2 SO 4 ). How many grams does he need? 1226 g

We could, on the other hand, give you GRAMS and ask you to find MOLES. That would be a GRAMS TO MOLES problem. Those problems you just finished were all “MOLES TO GRAMS ” problems because they GAVE you moles and asked you to find grams.

For example: How many moles are in 250 grams of Carbon? START with what they give you 250 grams MULTIPLY X By a conversion factor that connects moles to grams. How many grams in ONE mole of carbon? 1 mole C grams NOTE: The grams in the first number and the grams in the bottom of the conversion factor will cancel each other out, leaving moles!!! = moles

Another example, this time a little trickier: How many moles are in 930 grams of carbon dioxide (CO 2 )? START with what they give you 930 grams MULTIPLY X By a conversion factor that connects moles to grams. How many grams in ONE mole of carbon dioxide? 1 mole CO grams NOTE: The grams in the first number and the grams in the bottom of the conversion factor will cancel each other out, leaving moles!!! = moles

Practice Time!

How many moles are in 2.4 grams of sulfur (S)? How many moles are in 18.7 grams of argon (Ar)? How many moles are in 88.1 grams of potassium chloride (KCl)? How many moles are in 2.3 grams of nitric acid (HNO 3 )? How many moles are in 11.9 grams of calcium hydroxide - Ca(OH) 2 ? (Don’t forget! The 2 subscript applies to the O and to the H!!)

How many moles are in 2.4 grams of sulfur (S)? mol S How many moles are in 18.7 grams of argon (Ar)? mol Ar How many moles are in 88.1 grams of potassium chloride (KCl)? 1.18 mol How many moles are in 2.3 grams of nitric acid (HNO 3 )? mol How many moles are in 11.9 grams of calcium hydroxide - Ca(OH) 2 ? (Don’t forget! The 2 subscript applies to the O and to the H!!) 0.16 mol

Moles and Molecules 1 mole = 6.02 x particles (atoms, molecules, ions) A way of counting the number of atoms in a substance. The one always goes with mole! Solve using the same steps for conversions

Steps to conversions 1.Write the given. 2.Draw a “times and a line” 3.Write the units you were given on the bottom 4.Write the units you want on top 5.Fill in the conversion factor (remember 1 is always with the mole) 6.Multiply all the numbers on the top and divide it by the numbers on the bottom.

Using your calculator Graphing Calculators use parentheses around (6.02 x ) Enter 6.02 Find the EE or EXP button – This button tells your calculator x 10 Enter the exponent 23

Examples 1.How many moles are in 2.5 x molecules of water?

2. How many moles are in 3.9 x atoms of iron?

3. How many atoms are in 5 moles of Ne?

Stoichiometry The study of quantitative relationships between reactants and products Balanced chemical equations relate moles of reactants to moles of product N 2 + 3H 2  2NH 3 The coefficients are the mole ratio 1 mole of N 2 and 3 moles of H 2 make 2 moles of NH 3

Sample Problems 2 KClO 3  2KCl + 3O 2 2 moles of KClO 3 can produce __ moles of KCl. 4 moles of KClO 3 can produce __ moles of KCl.

Theoretical Yield Yield = the amount of product Goal – make as much of the product as possible Theoretical Yield – the most you should make as predicted by the chemical reaction using stoichiometry: N 2 + 3H 2  2NH 3

Actual Yield the amount of product actually produced in the lab Usually lower due to collection techniques and apparatus used If the amount is higher than predicted then there may be impurities in the product

Percent Yield Measures how well you did the lab Percent yield = Actual yield x 100 theoretical yield

Do Now Balance the reaction ____ NaCl + ____ F 2  ____ NaF + ____ Cl 2 For every 2 moles of NaCl, ___ moles of NaF are produced. For every 2 moles of NaCl, ___ moles of Cl 2 are produced. For every 4 moles of NaCl, ____ moles of NaF are produced.

Work on assignment 8 Try the practice quiz Do NOT copy

Limiting Reactant The reactant that is used up first Making a bicycle requires 1 frame + 2 wheels  1 bicycle If you have 10 frames and 12 wheels, how many bicycles can you manufacture? What is the limiting reactant?