The Mole

Unit: The Mole Topic: Atomic Mass Objectives: Day 1 of 4 To learn how atomic mass is calculated using the average natural abundance of isotopes To understand the quantity of a mole and Avogadro's number

Quickwrite Answer one of the questions below 1-2 sentences: 1 light year (the distance light travels in a year) is equal to 9.5 trillion kilometers!!!!!!!!!! Why do you think scientists use light years to measure distances to nearby stars in light years and not kilometers????? Your pencil uses graphite (pure carbon) to write with; how many atoms do you think are in 12 grams of graphite or carbon???????? How many items make up a dozen????? How many items make up a half dozen???? How many items are in two dozen??

The Mole In 1811, an Italian scientist by the name of Avogadro, Amedeo (1776–1856) discovered that a mole of atoms is equal to the number 6.022 x1023 In other words: 1 mole = 6.022 x1023 Or, or if you have a mole of carbon atoms, then you have 6.022 x1023 atoms

Number of Atoms Present How many atoms does A mole of hydrogen contain? Element Number of Atoms Present Hydrogen 6.022 x1023 Helium Carbon Nitrogen Oxygen Aluminum Sodium How many atoms does a mole of nitrogen contain? How many atoms does A mole Carbon contain? How many atoms does A mole of helium contain? The point is, a MOLE of anything has 6.022 x1023 atoms! 6.022 x1023 6.022 x1023 6.022 x1023 6.022 x1023

What is a Mole? The amount of a substance that is equal to Avogadro's number, __________, which is the amount of atoms found in 12 grams of carbon Write: Answer Bank 12.01 Atoms 24 Amount 6.022 x 1023(2) 1 Mole 1 Mole 12 grams of Carbon Or Or 6.022 x 1023 atoms 12 grams of Carbon 6.022 x 1023atoms

The Mole As it turns out, one mole of anything contains 6.022 x1023 units of that substance Just as a dozen eggs is 12 eggs, a mole of eggs is 6.022 x1023 eggs The mole is an incredibly large number to imagine - 602,000,000,000,000,000,000,000!!!!!!!!!!!!!!!!! We use scientific notation to simply this number We call this unbelievably large number Avogadro’s number

The Mole If I have a dozen eggs how many eggs do I have? If I have 2 dozen eggs, how many eggs do I have? If I have a mole of eggs, how many eggs do I have? If I have a 2 mole of eggs, how many eggs do I have? (2) x (6.022 x 1023)

What is Avogadro’s Number? The amount of _____ in 1 mole of a substance which is ________ Just as two dozen is (2) x (12), or ____eggs, 2 moles of atoms is equal to (2) x (6.022 x 1023 ) atoms Answer Bank 12.01 Atoms 24 Amount 6.022 x 1023(2)

The Mole Take out your periodic table and find Carbon Look Below the Atomic Symbol (C) What number do you see??? That’s right, 12.01 !!!!!!!!!!!! Below every atomic symbol is number called the ATOMIC MASS A sample of carbon with a mass of 12.01 has 6.022 x1023 atoms! So we can say that a mole of hydrogen (H) atoms has a mass of 1.01g, a mole of oxygen, (O) has a mass of 16.00g, a mole of iron (Fe) is 55.80g, and so on

1.008 grams 4.00 grams 12.01 grams 14.01 grams What is the MASS or weight of a MOLE of Hydrogen? What is the MASS or weight of a MOLE of Helium? Element Number of Atoms Present Average Atomic Mass in grams Hydrogen 6.022 x1023 1.008 Helium 4.00 Carbon 12.01 Nitrogen 14.01 Oxygen 16.00 Aluminum 26.98 Sodium 22.99 What is the MASS or weight of a MOLE of Nitrogen? What is the MASS or weight of a MOLE of Carbon? The point is, a sample Of any element that weighs A number of grams equal To the average atomic mass of that element contains 6.022 x1023 atoms! Or a MOLE!!! 1.008 grams 4.00 grams 12.01 grams 14.01 grams

Atomic Mass The average atomic mass for carbon is 12.01 amu Where does the 0.01 come from? 0.01 is the percent abundance in nature of the carbon isotopes For example, if we weighed 12 grams of carbon, 0.01% percent is the amount of Carbon 14 and Carbon 13 isotopes that exist in nature

Atomic Mass It is the average mass of an element containing 6.02 x 1023 atoms and calculated using the relative abundance of isotopes in a naturally-occurring element It is based on AMU’s and the natural abundance of an elements isotopes

What is atomic mass? It is the _________ mass of an element containing 6.02 x 1023 atoms and calculated using the relative abundance of isotopes in a naturally-occurring element For example a sample of Carbon containing 6.02 x 1023 atoms has a mass of ____grams and a sample of Iron containing 6.02 x 1023 atoms has a mass of ____grams Answer Bank average 1/12 simplify Carbon 55.8 abundance Neutron 12.01

The Mole Consider the following sample of CARBON atoms below (symbolized by red dots) which contains one mole (6.022 x 1023) of CARBON atoms Now consider another sample in which the number of CARBON atoms is unknown Sample A = 12.01 grams Sample B = 6.005 grams

The Mole We know sample A has 6.022 x1023 Carbon atoms But how many atoms are in sample B? We know the mass is 6.005 grams Sample A = 12.01 grams Sample B = 6.005 grams

The Mole Let’s consider what we know We know that 1 mol of Carbon atoms has a mass of 12.01 grams Sample B has a mass of 6.005 grams which is exactly half the mass of a mole of Carbon atoms Sample A = 12.01 grams Sample B = 6.005 grams

The Mole Let’s consider what we know We know that 1 mol of CARBON atoms has a mass of 12.01 grams Sample B has a mass of 6.005 grams which is exactly half the mass of a mole of CARBON atoms Sample A = 12.01 grams Sample B = 6.005 grams

Our conversion factor is: The Mole Our conversion factor is: 1mol CARBON 12.01 grams Let’s do the math! 6.005 grams of carbon 1 mol carbon We know we have 0.500 grams of hydrogen = 0.50 mol of Carbon in sample B 12.01 grams of carbon Sample A = 12.01 grams Sample B = 6.005 grams

Our conversion factor is: The Mole Our conversion factor is: 6.022 x1023 1 mol Now that we have moles, we can compute the number of atoms by using our conversion factor 0.50 mol of carbon 6.022 x1023 carbon atoms We solved for moles In the last example = 3.0 x1023 carbon atoms in sample B 1 mol of carbon Sample A = 12.01 grams Contains 6.022 x1023 Atoms Sample B = 6.005 grams Contains ???? Atoms

Practice: Your chicken laid 562 eggs. How many dozen eggs do you have?

Practice: If you have 9.39 x1023 Aluminum Atoms, how many moles do you have? 1.56 mol of aluminum? Number of atoms number of mols 9.39 x1023 lAl Atoms 1 mol Al = 1.56 Moles of Al 6.022 x1023 Al atoms

Practice: How many moles are in a 42 gram sample of aluminum? 42 grams Al 1 mol aluminum = 1.56 mol of Aluminum 26.98 grams Al

Practice: How many atoms are in a 18 gram sample of carbon? number of atoms 18 grams C 6.022 x1023 C atoms = 9.07 x1023 Carbon Atoms 12.01 grams C

Practice: Zagot Lab 1 zagot is equal to 150 atoms or 1 zagot = 150 atoms. If one atom has a mass of 2 grams, what is the mass or weight of one zagot? 150 atoms 2 grams = 300 grams 1 atom

Practice: Zagot Lab 1 zagot is equal to 1.5x102 atoms or 1 zagot = 150 atoms. If one atom has a volume of 0.2 mL, what is the mass or weight of one zagot? 150 atoms 0.2mL = 300 grams 1 atom Instead of counting out 150 atoms and weighing them, We can simply continuously add atoms on a scale until The weight is 300 grams. When the mass reads 300g, You know you have 300 atoms!!!!

Summarize: If I have a _____of something I have_______ particles Avogadro number is ___________ A mole of carbon atoms weigh (mass) ______ grams and contains ______ atoms 2 moles of carbons atoms weighs _____ grams Review: An ______ is atom with a different amount of neutron than protons Answer Bank 12.01 Atoms isotope Mole 24.02 Amount 6.022 x 1023(2)

Topic: Molar Mass (Molecular Weight) & Percent Composition Unit: The Mole Topic: Molar Mass (Molecular Weight) & Percent Composition Objectives: Day 2 of 4 To learn how to calculate Molar Mass To learn how to convert between moles and grams To learn how to calculate % composition

Quickwrite Answer one of the questions below 1-2 sentences: Let’s say you want to find the weight of your dog, which is too big to stand on your bathroom scale; how could you find his weight??? Together, you and your dog weigh 100 kilograms, you know that you weigh 75 kilograms, what percent by weight does your dog weigh???? You know that a mole oxygen has a mass of 16grams and a mole of hydrogen has a mass of 1.0 grams, but how could you find the mass of 1 mole of water (H2O)

Molar Mass of a Compound 1 mole of H2O = 6.02 x 1023 Molecules of H2O Earlier we learned that a mole of any element contains 6.02 x1023 atoms But what about a compound or Molecule such as water (H2O)? A chemical compound such as water (H2O) is a collection of atoms Water contains 1 oxygen atom and 2 hydrogen atoms But how do we calculate the mass of one mole of water? In other words, what is the mass of 6.022 x1023 H2O Water molecules?

Molar Mass of a Compound 1 mole of H2O = 6.02 x 1023 Molecules of H2O If we put one mole of water (H2O) on a scale and mass it, it will read 18.02 grams But how did we come up with that number? Well, we know water is made up of Oxygen and Hydrogen We also know the mass of one mole of Oxygen by looking on our periodic table 16.00 grams We also know the mass of one mole of Hydrogen by looking on our periodic table 1.01 grams Finally, we also know that water contains 2 Hydrogen atoms 18.02 grams

Molar Mass of a Compound 1 mole of H2O = 6.02 x 1023 Molecules of H2O And contains 1 mole of Oxygen Atoms And 2 moles of Hydrogen atoms Because each water molecule (H2O) contains 1 Oxygen atom and 2 Hydrogen atoms, 1 mol (H2O) molecules consists of 1 mol Oxygen atoms and 2 mol of Hydrogen atoms So the mass of 1 mol of (H2O) is equal to: Mass of 1 mol of Oxygen (O) = 1 x 16.00g = 16.00 g Mass of 2 mol of hydrogen (H) = 2 x 1.01 = 2.02g _______ Mass of 1 mol of (H2O) = 18.02 g

Molar Mass of a Compound Molar Mass is the mass in grams of 1 Mole of a substance or compound It is calculated by the SUM of the atomic weights for every element that makes up the compound Ex: H2O Mass of 1 mol of Oxygen (O) = 1 x 16.00g = 16.00 g Mass of 2 mol of Hydrogen (H) = 2 x 1.01 = 2.02g _______ Mass of 1 mol of (H2O) = 18.02 g

What is molar mass or molecular weight? Answer Bank Total Percent Element Adding 6.02 x 1023 mole weight It is the mass in grams of 1 _____ of a substance or compound containing ______ molecules of that substance It is calculated by the sum or ______up the atomic mass for every element that makes up the compound Ex: H2O Mass of 1 mol of Oxygen (O) = 1 x 16.00g = 16.00 g Mass of 2 mol of Hydrogen (H) = 2 x 1.01 = 2.02g _______ Mass of 1 mol of (H2O) = 18.02 g

Mass of 1 mol of (SO2) = 64.07 g/mol Practice: Calculate the molar mass of sulfur dioxide(SO2): Mass of 1 mol of sulfur (S) = 1 x 32.07 g = 32.07 g Mass of 2 mol of oxygen (O) = 2 x 16.00 g = 32.00 g _______ Mass of 1 mol of (SO2) = 64.07 g/mol

Mass of 1 mol of (CaCO3): = 100.09 g Practice: A sample of calcium carbonate (chalk) contains 4.86 mol. What is the mass in grams of this sample: First calculate the molar mass of CaCO3: Mass of 1 mol of Calcium (Ca)=1 x 40.08 g = 40.08 g Mass of 1 mol of Carbon (C) =1x 12.01 g = 12.01 g Mass of 3 mol of Oxygen (O) =3 x 16.00 g = 48.00 g _______ Mass of 1 mol of (CaCO3): = 100.09 g 4.86 mol CaCO3 = 486 grams CaCO3 100.09 grams CaCO3 1 mol CaCO3

Practice: A sample of water weighs 20.56 grams. How many water molecules are in a sample of water that weighs 20.56 grams? 20.56 gms H2O 6.022 x1023 H2O molecules =6.87 x 1023 molecules 18.016 gms H2O

Percent Composition: part/whole Percent Composition is the percent by mass of an element in a compound or molecule % composition for each element is calculated as follows: For Example: Mass % is calculated by comparing the mass of a single element to the total mass (molar mass) of the compound % Composition of an element = Mass of the 1 mole of the element Mass of 1 mol of compound Mass of the 1 mole of the Oxygen (O) Mass of 1 mol of Water (H2O) % Composition = of Oxygen in H2O

Percent Composition = 16.00 g O x 100 = 89.0 % O For example, lets consider methane (H2O): We calculate the mass of each element present and the molar mass of ethanol as follows: Mass of O = 1 mol O = 16.00 g O x 100 = 89.0 % O 18.02 g H2O 16.00 grams O 1 mol O Mass of H = 2 mol H = 2.02 g H x 100 = 11.0% H 18.02 g H2O 1.01 grams H 1 mol H Mass % of O = 89.0 % O Mass % of H = 11.0 % H 100.00 % H2O So we say the compound water H2O is 89.0 % Oxygen and 11.0% Hydrogen

What is Percent Composition? The ________by mass of an ________ in a compound or molecule Mass % is calculated by comparing the mass of a single element to the _____ mass (molar mass) of the compound Answer Bank Total Percent Element adding mole masses _Part___ x 100 = % composition Whole

Practice: Find the weight percent of Oxygen and Sulfur in SO2 Sulfur Dioxide: Mass of S = 1 mol S = 32.07g S x 100 = 50.00 % S 64.07g SO2 32.07 grams S 1 mol S Mass of O = 2 mol O = 32.00 g O x 100 = 50.00 % H 64.07g SO2 32.00 grams O 1 mol O Mass % of S = 50.00 % S Mass % of O = 50.00 % O 100.00 % SO2 So we say the compound SO2is 50.00 % Sulfur and 50.00% Oxygen

Summarize: Explain Molar mass in your own words: Describe and explain how you would calculate % compostion: _____ _____is the mass in grams of one mole of a compound which contains 6.02 x 1023 molcules To calculate Molar mass, you would add up the ____ ______for each element that make up a molecule The percent by mass of an element in a compound is called it’s ______ ______ Calculate the percentage of nitrogen in nitrogen dioxide NO2

Topic: Molecular and Empirical Formulas Unit: The Mole Topic: Molecular and Empirical Formulas Objectives: Day 3 of 4 To understand the difference between molecular and empirical formulas To learn how to calculate empirical formulas and molecular formulas given percent composition and mass

Quickwrite Answer one of the questions below 1-2 sentences: Review: In iron (III) oxide, Fe2O3, how many iron atoms are present? How many oxygen atoms are present? How do think scientists determine the subscripts on chemical formulas such as Fe2O3? In other words how did they come up with the subscripts 2 and 3? Can hydrogen peroxide (H2O2) be simplified into a more basic chemical formula? If so, how?

Empirical Formulas The formula for a compound that is determined experimentally. A formula that represents the Smallest whole-number mole ratio of the different atoms in the compound. In other words, it is the simplest formula for a compound.

Empirical Formula Molecular Formula Empirical Formula H2O2 HO CH2O Molecular Formula A formula based on the actual numbers of atoms of each type in the Empirical Formula A formula that gives the simplest whole-number ratio of the atoms of each element in a compound. Molecular Formula Empirical Formula H2O2 HO CH2O C6H12O6 CH3O CH3O C2H4O2 CH2O

What is an Empirical Formula?? A formula that represents the _____ whole-number ratio of the different atoms in the compound. In other words, it is the _____ formula for a compound. Example glucose Answer Bank Simplest Numbers oxygen Smallest CH2O Molecular Formula Empirical Formula C6H12O6 ??????

Practice: Write the empirical formula for N2O4 A formula that represents the Using the smallest or lowest whole-number ratio of N2O4 we get…. N2O4 NO2

Steps for determining Empirical Formulas Assume a 100 g sample when given percents. This makes 10.3 % = 10.3 g Convert grams into moles for each element. Divide all the moles by smallest number of moles to get the lowest whole number ratio. Write the empirical formula.

Therefore the empirical formula is CaCl2 A compound was found to contain 36.11 % calcium and 63.89 % chlorine by mass. What is its empirical formula? What assumption did you make? 36.11 % Ca = 36.11 g Ca 63.89 % Cl = 63.89 g Cl Step 1 Assume a 100 g sample when given % Step 2 Convert grams into moles for each element. Step 3 Divide the all the moles by smallest number of moles 1 mol Ca = 0.9009 mol Ca = 1 mol Ca 40.08g Ca 0.9009 1 mol Cl = 1.802 mol Cl = 2 mol Cl 35.45g Ca 0.9009 Step 4 Write the empirical formula Therefore the empirical formula is CaCl2

This gives us the empirical formula is Fe1O1.4 Problem: Write the Empirical Formula for a compound composed of: 72% iron and 27.6% oxygen by mass. 72.% Fe = 72.00 g Fe 27.6 % O = 27.60 g O Step 1 Assume a 100 g sample when given % Step 2 Convert grams into moles for each element. Step 3 Divide all the moles by smallest number of moles 1 mol Fe = 1.230 mol Fe = 1 mol Fe 55.84g Fe 1.230 1 mol O = 1.730 mol O = 1.4 mol O 16.00g O 1.230 Step 4 Write the empirical formula This gives us the empirical formula is Fe1O1.4 Since 1.4 atoms does not exist in nature, we need to multiply the compound by 2, so we get 2(Fe1O1.5) = Fe2O3

Molecular Formulas C2H4O2 For example, consider glucose or sugar: A molecular formula is based on the actual number of atoms in each type of compound or molecule For example, consider glucose or sugar: The molecular formula tells us that it contains 2 Carbon atoms, 4 Hydrogen atoms, and 2 Oxygen atoms C2H4O2 52

What is a Molecular Formula? A formula based on the actual _______ of atoms in each type of compound or molecule Example: glucose C2H4O2 has 2 Carbon atoms, 4 Hydrogen atoms, and 2 ______ atoms Answer Bank Simplest Numbers oxygen Smallest CH2O 53

Steps for determining Molecular Formulas 1. Find molar mass of the empirical formula 2. The molar mass of the molecule will be given. 3. Divide ___molar mass _of molecule___ molar mass of Empirical Formula 4. Multiply your answer from “step 3” by the subscripts given in the empirical formula.

1. Find molar mass of the empirical formula Practice: Find the molecular formula for a compound with an empirical formula of CH4N if the molar mass of the molecule is 60.12 g/mole. 1. Find molar mass of the empirical formula Molar mass of Empirical Formula – CH4N C = 1.0 x 12.0 = 12.0 g/mole H = 1.0 x 4 = 4.0 g/mole N = 1.0 x 14 = 14.0 g/mole Molar mass of Empirical Formula = 30.0 g/mole 2. The molar mass of the molecule will be given. Molar mass molecule (given) = 60.12 g/mole

Practice: Find the molecular formula for a compound with an empirical formula of CH4N if the molar mass of the molecule is 60.12 g/mole. 3. Divide __molar mass _of molecule___ molar mass of Empirical Formula ____Molar Mass _molecule____ = 60.12 g/mole = 2.00 Molar mass Empirical Formula 30.0 g/mole 4. Multiply your answer from the previous step by the subscripts given in the empirical formula. 2(CH4N) = C2H8N2 Therefore the Molecular Formula is C2H8N2

1. Find molar mass of the empirical formula Practice: Determine the molecular formula of a compound with an empirical formula of NH2 and Molecular or molar mass of 32.06 g/mole. 1. Find molar mass of the empirical formula Molar mass of Empirical Formula – NH2 N = 1 x14.0 = 14.0 g/mole H = 2.0 x 1 = 2.0 g/mole Molar mass of Empirical Formula = 16.0 g/mole 2. The molar mass of the molecule will be given. Molar mass molecule (given) = 32.06 g/mole

Practice: Determine the molecular formula of a compound with an empirical formula of NH2 and Molecular or molar mass of 32.06 g/mole. 3. Divide ______molar mass _of molecule_______________ molar mass of Empirical Formula __ __ Molar Mass _molecule____ = 32.06 g/mole = 2.00 Molar mass Empirical Formula 16.0 g/mole 4. Multiply your answer from the previous step by the subscripts given in the empirical formula. 2(NH2) = N2H4 Therefore the Molecular Formula is N2H4

Summarize: Compare and contrast the empirical formula with the molecular formula: Can the empirical formula be the same as the molecular formula???? What do you do if the subscript is not a whole number such as 1.4???? Complete the table: Molecular Formula Empirical Formula P4O6 C6H9

Topic: Moles in Chemical Reactions Unit: The Mole Topic: Moles in Chemical Reactions Objectives: Day 4 of 4 To learn how we go from moles of a reactant to moles of a product To learn how to calculate between moles of reactants to moles of products

Quickwrite Answer one of the questions below 1-2 sentences: A cake recipe requires 2 eggs, 2 cups of flour and 1 cup of sugar; you need to make 50 cakes for a friends birthday party, how many eggs, cups of flour and sugar should you buy???? Using the recipe below: 2 eggs + 2 cups of flour + 1 cup of sugar → 1 cake To make one cake, a recipe requires how many cups of flour? How could you write this as a ratio?

Moles in Reactions Chemistry is really all about reactions Reactions involve the rearrangement of atoms The calculation of the quantities of chemical elements or compounds involved in chemical reactions is called Stoichiometry (our next unit) It is the coefficients in the balanced chemical equation that enables us to determine just how much product forms What we once called coefficients are now called moles!!!!

Moles in Reactions To explore this idea, consider a non-chemical analogy A particular cake recipe requires 2 eggs, 2 cups of flour, and 1 cup of sugar Or, you might represent this by: 2 eggs + 2 cups of flour + 1 cup of sugar → 1 cake

Moles in Reactions Now, lets say you need to make 50 cakes for a large party You will need ingredients to make 50 cakes How do you figure out how much of each ingredient you need to buy? You could multiply the previous equation by 50: 50(2 eggs) +50 (2 cups of flour) + 50(1 cup of sugar) → 50 (1 cake) 100 eggs+ 100 cups of flour + 50 cups of sugar→ 50 cakes

Moles in Reactions Notice that the numbers 100:100:50 correspond to the ratio 2:2:1 The equation for chemical reaction gives you the same type of information It indicates the relative numbers of reactant and product molecules required for the reaction to take place

Moles in Reactions To illustrate how this idea works, consider the reaction between gaseous carbon monoxide and hydrogen to produce liquid methanol The reactants and products are: Unbalanced: CO(g) + H2(g) → CH3OH(l) Because atoms are just rearranged (not created or destroyed) in a chemical reaction, we must always balance the chemical equation

Moles in Reactions Balanced: CO(g) + 2H2(g) → CH3OH(l) It is important to recognize that the coefficients in a balanced equation give the relative number of molecules That is, we could multiply this balanced equation by any number and still have a balanced equation For example, we could multiply by 12, 12 [CO(g) + 2H2(g) → CH3OH(l) ] to obtain 12 CO(g) + 24H2(g) → 12 CH3OH(l)

Moles in Reactions 12 CO(g) + 24H2(g) → 12CH3OH(l) Is this still a balanced equation??? Yes!!!! Because 12 represents a dozen, we could even describe the reaction in terms of dozens: 1 dozen CO(g)+ 2 dozen H2(g) →1 dozen CH3OH(l) We could also multiply the original equation by a very large number, such as 6.022 x 1023

Moles in Reactions Which leads to the equation below: 6.022 x 1023 [ CO(g) + 2H2(g) → CH3OH(l) ] Which leads to the equation below: 6.022 x 1023 CO(g) + 2(6.022 x 1023 )H2(g) → 6.022 x 1023 CH3OH(l) Who wants to work with such a large number???? We also know this number 6.022 x 1023 is equal to What????? 1 Mole!!!!! Let’s replace 6.022 x 1023 with 1 Mole!!!!! Re-written in terms of moles we get: 1 mol CO(g) + 2 mol H2(g) → 1 mol CH3OH(l) 1 CO(g) + 2 H2(g) → 1 CH3OH(l)

Moles in Reactions 2H2(g) + O2(g) → 2H2O(l) Think of the number of moles in a chemical reaction as the amount of ingredients necessary for the reaction to take place Just like you need a certain amount ingredients to make a cake, you also need a certain amount of ingredients, or in this case molecules for a chemical reaction We can use an equation to predict the moles of products that a given number of moles of reactants will produce For example, consider the combination oxygen and hydrogen gas to synthesize water: 2H2(g) + O2(g) → 2H2O(l) The equation tells us that 2 mol of H2 reacts and requires 1 mol of O2 to create or produce 2 mol of H2O

Mole Ratio 2H2(g) + O2(g) → 2H2O(l) Remember, the above equation tells us that 2 mol of H2 reacts with 1 mol of O2 to create or yield 2 mol of H2O We can write this as a ratio: Or, we can use this ratio: This ratio is important because it allows us to go from moles of reactants to moles of products The mole ratio is defined as a conversion factor that allows us to go from moles of reactants to moles of products moles of A on the reactant side moles B on the product 2 moles H2O or 2 moles H2__ 2 moles H2 2 moles H2O 2 moles H2O or __1 moles O2___ 1 moles O2 2 moles H2O

What is the mole ratio? A __________ factor that takes us from moles of ________ to moles of ________in a chemical reaction Answer Bank Reactants conversion moles Quantities Reactions products moles of A on the reactant side moles B on the product

Moles in Reactions 2H2(g) + O2(g) → 2H2O(l) Remember, the equation tells us that 2 mol of H2 reacts and requires 1 mol of O2 to create or produce 2 mol of H2O 2H2(g) + O2(g) → 2H2O(l) But we if double the reactants? That would give us: 2[2H2(g) + O2(g) → 2H2O(l)] or 4H2(g) + 2O2(g) → 4H2O(l) This equation tells us that 4 mol of H2 reacts and requires 2 mol of O2 to create or produce 4 mol of H2O Or what if we Triple the reactant quantities? That would give us: 3[2H2(g) + O2(g) → 2H2O(l)] or 6H2(g) + 3O2(g) → 6H2O(l) This equation tells us that 6 mol of H2 reacts and requires 3 mol of O2 to create or produce 6 mol of H2O

NO2(g) + H2O (l) → HNO3(aq) + NO (g) Practice: First balance the equations below and determine the mole ratios NO2(g) + H2O (l) → HNO3(aq) + NO (g) Determine the mole ratio for NO2 and HNO3 C6H6 (g) + H2 (g) → C6H12(g) Determine the mole ratio for H2 and C6H12 3 2 3 moles of NO2 or 2 moles of HNO3 2 moles of HNO3 3 moles of NO2 3 3 moles of H2 or 1 moles of C6H12 1 moles of C6H12 3 moles of H2

Mole Ratio The mole ratio tells us how many moles of Reactant OR Product will form in a chemical reaction For example, consider the decomposition of water to produce hydrogen gas and oxygen: 2H2O(l) → 2H2(g) + 1O2(g) Remember, equation tells us that 2 mole of H2O will produce 2 moles of H2 and 1 mole of O2 But what if I have 4 moles of H2O???? Well, then I can produce 4 moles of H2 and 2 moles O2 But what if I have 10 moles of H2O???? Well, then I can produce 10 moles of H2 and 5 moles O2

Mole Ratio 2H2O(l) → 2H2(g) + 1O2(g) The mole ratio tells us how many moles of Reactant OR Product will form in a chemical reaction For example, consider the decomposition of water to form hydrogen and oxygen gas : 2H2O(l) → 2H2(g) + 1O2(g) The equation tells us that 2 moles of H2O will produce 2 moles of H2 and 1 mole of O2 In other words if I have 10 moles of H2O, then I can produce 10 moles of H2 and 5 moles of O2

Practice: Using the equation: 2H2O(l) → 2H2(g)+ O2(g) How many moles of O2 are produced by 4 moles of water??? Using the equation: 2H2O(l) → 2H2(g)+ O2(g) How many moles of O2 are produced by 1 mole of water???

Practice: (Record you solution in the answer bank) Using the equation below, what number of moles of O2 will be produced by the decomposition of 6.4 mol of water 2H2O(l) → 2H2(g) + O2(g) 6.4 mol H2O 1 mol O2 = 3.2 mol of O2 2 mol H2O

Practice: (Record you solution in the answer bank) Using the equation below, calculate the number of moles of NH3 that can be made from 1.3 mol H2 N2(g)+ 3H2(g) → 2NH3(g) 1.3 mol H2 2 mol NH3 = 0.867 mol of NH3 3 mol H2

Practice: (Record you solution in the answer bank) How many moles of N2 are needed to produce 8.5 moles of NH3? N2(g)+ 3H2(g) → 2NH3(g) 8.5 mol NH3 1 mol N2 = 4.25 mol of N2 2 mol NH3

Practice: Using the equation below, calculate the number of grams of NH3 that can be made from 3.9 mol H2 reacting with excess N2 N2(g)+ 3H2(g) → 2NH3(g) 3.9 mol H2 2 mol NH3 17.0 g of NH3 = 44.2 grams of NH3 3 mol H2 1 mol NH3

Summarize: Consider the decomposition reaction of high quality H2O: 2H2O ---> 2H2(g) + O2(l) If you have 2 moles of H2O Then how many moles of……. If you have 4 moles of H2O If you have 1 mole of H2O O2 would form? ____________ H2 would form? ____________