Pre-AP 2/8 : 1. Please place your project on a back lab station (STAPLE THE RUBRIC ON FRONT, then the calculations, then the information sheet) 2. Also turn in the molecular formula calculations 3. Take out the review of topics learned 4. WE will finish the review and then you will take a quiz over everything we have learned so far. 5. If we have enough time, we will start the mole part of this unit and possibly go outside to write our name in chalk 6. You have NO HW tonight.

Review of Topics Learned: 1. Calculate the molar mass of: A. magnesium sulfate A. magnesium sulfate B. silver (I) bromide B. silver (I) bromide 2. What is the percent composition of oxygen in calcium hydroxide? 3. What is the empirical formula for a compound which contains g of iron, g of sulfur and g of oxygen? 4. Given the following data, find the correct molecular formula 24.3 % C, 4.1 % H, 71.6 % Cl, molecular formula mass = g.

Counting Atoms

On the back of the lab paper answer: how many grams and atoms are in the mole of silver (left pic) and how many grams and atoms are in the mole of carbon (right pic)?

During the lab…. You need to measure all ten elements and write down the exact number given to you on the scale. PLEASE DO NOT OPEN BAG. Make sure you take into consideration the mass of the baggie (1.0 g) when determining the mass of the element. When you and your partner have measured all ten elements, have a seat and start trying to convert the masses to number of moles. There is a sheet to help you determine how to calculate this conversion. Please read this sheet and try ON YOUR to calculate moles.

1/27 HAPPY FRIDAY! Please pick up the paper from the side table. You will have ten minutes to complete the mole and atoms conversion lab from yesterday.

The pictures below show a mole of water and a mole of gold. Determine the mass of each. Also determine the number of atoms in the gold and the number of molecules in water.

Pre-AP 2-9 Please pick up the chalk lab from the side table AND A PIECE OF PAPER. Please pick up the chalk lab from the side table AND A PIECE OF PAPER. Today we will: Today we will: 1. Pass back papers 1. Pass back papers 2. Learn about the mole 2. Learn about the mole 3. Perform a chalk lab 3. Perform a chalk lab

Relating Mass to Number of Atoms How can the mass of an element from the periodic table be related to the actual number of atoms that are present in a sample? Use: The mole Avogadro’s number Molar mass

The Mole Definition-the amount of substance that contains as many particles as there are atoms in exactly 12 g of carbon-12. Huh? If you weighed exactly 12 g of carbon-12 and counted every single atom in your pile, the number of atoms present is defined as 1 mol. Think of it like exactly 12 eggs are in 1 dozen.

Avogadro’s Number So how many carbon-12 atoms would be in that pile? X Rounded to X This number is “nicknamed” Avogadro’s number after the Italian scientist Amedeo Avogadro. A mole of any substance contains X10 23 particles, just like 1 dozen of any substance contains 12 particles.

If every person on earth (5 billion) counted continuously at 1 atom per second, it would take 4 million years for all atoms in one mole to be counted!

 The mass of 1 mole of a pure substance is called the molar mass  Equality that relates number of grams in a mole  Molar mass is equal to the atomic mass of an element  The unit for atomic mass is grams per mole (g/mol) Molar Mass

Pre-AP 2/11 Pick up the papers from the side table AND grab a calculator (if the calculator needs batteries, come see me). Pick up the papers from the side table AND grab a calculator (if the calculator needs batteries, come see me). Find your ASSIGNED SEAT PLEASE. THERE IS A STICKY NOTE WITH YOUR NAME ON IT. Find your ASSIGNED SEAT PLEASE. THERE IS A STICKY NOTE WITH YOUR NAME ON IT. Please take out the paper you made on Tuesday (A-M-G) AND a piece of notebook paper Please take out the paper you made on Tuesday (A-M-G) AND a piece of notebook paper Today we will practice converting problems involving moles, grams, atoms/molecules. Today we will practice converting problems involving moles, grams, atoms/molecules. WE will also do a station rotation ON THE DESKS to review for test. (scheduled for tomorrow BUT that may change. WE will also do a station rotation ON THE DESKS to review for test. (scheduled for tomorrow BUT that may change.

Pre-AP 2/12 Pick up the review from the side table AND grab a calculator. Find your ASSIGNED SEAT PLEASE. THERE IS A STICKY NOTE WITH YOUR NAME ON IT. Pick up the review from the side table AND grab a calculator. Find your ASSIGNED SEAT PLEASE. THERE IS A STICKY NOTE WITH YOUR NAME ON IT. Please take out the paper you made on Tuesday (A-M-G) AND a piece of notebook paper Please take out the paper you made on Tuesday (A-M-G) AND a piece of notebook paper Today you will perform a station rotation ON THE DESKS to review for test. (scheduled for TUESDAY) Today you will perform a station rotation ON THE DESKS to review for test. (scheduled for TUESDAY) Study over the weekend. The answers to the review are on my website. Study over the weekend. The answers to the review are on my website.

CONCEPTUAL WARM-UP (write your answer on a piece of scratch paper): The pictures below show a mole of water and a mole of gold. 1. Determine the mass (g) of each. Also determine the number of atoms in the gold and the number of molecules in water.

Now try this one… 1. How many grams AND how many atoms are in the mole of silver (left pic)? 2. How many grams and atoms are in the mole of carbon (right pic)?

Atoms, Moles, & Molar Mass can be used as conversion factors! When performing conversion between atoms, moles, and grams (molar mass), remember: When performing conversion between atoms, moles, and grams (molar mass), remember: AGM

When using masses from the periodic table, round to two decimals for all calculations!

Conversion Example 1 : M-G What is the mass, in grams, of 2.67 mol of the element copper, Cu? What is the mass, in grams, of 2.67 mol of the element copper, Cu? Given: 2.67 mol Cu Given: 2.67 mol Cu Unknown: ? g Cu Unknown: ? g Cu

Conversion Example 2: A-M How many moles of oxygen, O, are in 2,000,000 atoms of oxygen? How many moles of oxygen, O, are in 2,000,000 atoms of oxygen? Given: 2,000,000 atoms O Given: 2,000,000 atoms O Unknown: ? mol O Unknown: ? mol O

Conversion Example 3 A-M Convert 5.00 X molecules of chlorine gas to moles

Conversion Example 4 G-A How many atoms are in 5.8 gram of copper? How many atoms are in 5.8 gram of copper?

Conversion Example 5 A-G Determine the mass in grams of X molecules of CO 2 Determine the mass in grams of X molecules of CO 2

The remainder of the period: You will be timed for 8 minutes at each station. You will be timed for 8 minutes at each station. You have this time to answer the question as a group. Write your OWN answers down on a piece of paper. You have this time to answer the question as a group. Write your OWN answers down on a piece of paper. When time is up: switch to the number FOLLOWING the one you started on. When time is up: switch to the number FOLLOWING the one you started on. HW for tonight: the review for the test and the AMG practice problems you picked up from side table. HW for tonight: the review for the test and the AMG practice problems you picked up from side table.

Molar Mass Used to Determine Percent Composition Molar mass-the mass of one mole of a compound

Why % composition? When a new compound is made or discovered, it is analyzed to determine its % composition. From this info, its empirical formula can be determined.

Percentage Composition Percentage by mass of each element in a compound Percentages should always total very close to 100! Always check!

Percentage Composition Example 1 Find the percentage composition of sodium nitrate. Formula of sodium nitrate: NaNO 3 Molar mass of NaNO 3 =85.00 g/mol Total100%

Percentage Composition Example 2 Find the percentage composition of silver sulfate. Formula of silver sulfate: Ag 2 SO 4 Molar mass of Ag 2 SO 4 = g/mol Total100.01%

Answer the following: 1. Why can a bug walk on water? 2. Explain capillary action. 3. If you drop a polar substance onto a surface why does it not increase surface area? 4. What is columbs law? What type of compound does it apply to? 5. Why is an ion induced dipole moment polarizable? Which is more polarizable: fluorine gas or chlorine gas when in close proximity to the aluminum ion?

2/2 AP A calculator, a periodic table, the empirical airlines flight 1023, and sit with ONE partner This project will be due Friday. We will discuss details in class. Please turn in the empirical formula worksheet at the beginning of class. It is late if you turn it in after. (should have been turned in yesterday) Today you will learn to determine molecular formula and then you will be given the rest of the period to work on the flight project. Please turn in the empirical formula worksheet at the beginning of class. It is late if you turn it in after. (should have been turned in yesterday )

Empirical Formula Simplified formula for a compound For an ionic compound, empirical formula is the compound’s formula unit because we always simplify the formula   Calcium sulfide: Ca 2 S 2  CaS For a molecular compound, may not represent actual number of atoms present in a molecule   Molecular formula: B 2 H 6   Empirical formula: BH 3

Empirical Formula C2H6C2H6 CH 3 reduce subscripts Smallest whole number ratio of atoms in a compound

How do you calculate empirical formula? 1. Write down the mass or % of each element given in the problem 2. Divide that number by the mass on the periodic table 3. Divide each number by the smallest number determined in step 2 4. IF you have a number in step 3 that isn’t a whole number (ex. 2.5), then multiply subscripts by 2, 3, or 4 to get whole #’s.

Empirical Formula Example 1 A compound consist of 75% carbon and 25% hydrogen by mass. Determine the empirical formula for this compound 75 g 1 mol g = 6.24 mol N 25 g 1 mol 1.01 g = mol O 6.24 mol = 1 C = 4 H

Empirical Formula Example 2 Find the empirical formula for a sample of 25.9% N and 74.1% O g 1 mol g = 1.85 mol N 74.1 g 1 mol g = 4.63 mol O 1.85 mol = 1 N = 2.5 O

Empirical Formula Example N 1 O 2.5 Need to make the subscripts whole numbers  multiply by 2 N2O5N2O5

Pre-AP 2/5 Pick up the paper from the side table Pick up the paper from the side table Today we will review all topics learned so far in this unit (empirical formula, molar mass, percent composition) Today we will review all topics learned so far in this unit (empirical formula, molar mass, percent composition) WE will learn how to calculate molecular formula from an empirical formula AND THEN POSSIBLY TAKE A QUIZ (if time permits) WE will learn how to calculate molecular formula from an empirical formula AND THEN POSSIBLY TAKE A QUIZ (if time permits) HW: empirical flight project is due Monday. HW: empirical flight project is due Monday.

Molecular Formula “True Formula” - the actual number of atoms in a compound CH 3 C2H6C2H6 empirical formula molecular formula ?

Pre-AP 2/4 You will be given ½ the period to work on your project. If you are taking advantage of the time allotted, I have MANY practice problems for you to work out. You will be given ½ the period to work on your project. If you are taking advantage of the time allotted, I have MANY practice problems for you to work out. The Empirical Flight project will be due on MONDAY. Please remember this is a summative grade. Do your best and be creative. The Empirical Flight project will be due on MONDAY. Please remember this is a summative grade. Do your best and be creative. For the other ½ of the period, we will review molar mass, percent composition, and empirical formula. You will learn to calculate molecular formula and then QUIZ. For the other ½ of the period, we will review molar mass, percent composition, and empirical formula. You will learn to calculate molecular formula and then QUIZ. There are no assignments to be turned in today and the only homework you have is to work on your project. There are no assignments to be turned in today and the only homework you have is to work on your project.

How do you calculate molecular formula? 1. Find the empirical formula. 2. Find the empirical formula mass. 3. Divide the molecular mass by the empirical mass. 4. Multiply each subscript by the answer from step 3.

Molecular Formula Example The empirical formula for ethylene is CH 2. Find the molecular formula if the molecular mass is 28.1 g/mol g/mol g/mol = 2.00 empirical mass (CH 2 ) = g/mol (CH 2 ) 2  C 2 H 4

Review of Topics Learned: 1. Calculate the molar mass of: A. magnesium sulfate A. magnesium sulfate B. silver (I) bromide B. silver (I) bromide 2. What is the percent composition of oxygen in calcium hydroxide? 3. What is the empirical formula for a compound which contains g of iron, g of sulfur and g of oxygen? 4. Given the following data, find the correct molecular formula 24.3 % C, 4.1 % H, 71.6 % Cl, molecular formula mass = g.

General pathway to solve problems Mass of each element Percent composition of compound Empirical formula for compound Molecular formula for compound

Molecular Formula Example A sample of a compound with a molar mass of g/mol is found to consist of 0.44 g H and 6.92 g O. Find its molecular formula % H, % O Empirical formula: HO Molecular formula: (HO) 2 =H 2 O 2