WED 9-16 AND THURS 9-17THE MOLE AND MOLE CONVERSIONSMrs. Wilson

DO NOW

Staple your lab rubric to the back of your Foul Water Lab. Make sure you’ve written your name and your partners’ names.Turn in your Foul Water Labs.Please follow the LASA honor code.

DAILY QUIZ 1-10 (it’s very easy )

OBJECTIVESCalculate the number of representative particles (atoms, ions, molecules, or formula units) in a sample of material if mass is given OR if # of moles are given.

Calculate the # of moles or the mass of a sample of material if the number of representative particles is given.

Homework: 1.9 Homework + Daily Quiz 1-10 Next Class

THE MOLEThe SI unit used to measure the amount of substance is the mole (Latin for “pile”)

The “mole” is a counting unit, used to make counting things much easier.

1 dozen of ANYTHING = 12 things1 mole of ANYTHING = 6.02 x 1023 things

6.02 x 1023 = Avogadro’s Number (symbol NA)THIS IS EQUAL TO THE NUMBER OF CARBON-12 ATOMS IN 12 G

OF CARBON-12. BUT… HOW DO WE COUNT ATOMS?

WEIGHING BY COUNTINGThis exercise is to help you understand that for chemists to count atoms, they have to weigh them.

Let’s say the mass of Cheerios in one box = 500. g (don’t worry about the box or the bag)A “gaggle” of Cheerios = 100 Cheerios.Mass of one “gaggle” = 15.0 grams

How many Cheerios are in the box? Use sig figs to express your final answer. (hint: # Cheerios is a counting unit, so don’t use 100 to help you determine sig figs.)

WEIGHING BY COUNTINGThis exercise is to help you understand that for chemists to count atoms, they have to weigh them.

Let’s say the mass of all Cheerios in one box = 500. g (don’t worry about the box or the bag)A “gaggle” of Cheerios = 100 Cheerios.Mass of one “gaggle” = 15.0 grams

How many Cheerios are in the box? 500. g / 15.0 g = 33.3 “gaggles”33.3 “gaggles” x 100 = 3.33 x 103 Cheerios

A WORD ON REPRESENTATIVE PARTICLES

Elements have ATOMSCovalent compounds have uncharged MOLECULES (groups of ATOMS)Covalent compounds = consist of nonmetal atoms only (found on right side of periodic table; H is also a nonmetal)

Ionic compounds have FORMULA UNITS (neutral groups of IONS)Ions = atoms or molecules that have gained or lost electronsIonic compounds = consist of metal ions and nonmetal ions (metals found on LEFT and MIDDLE side of periodic table)

DETERMINE THE NAME AND NUMBER OF THE REPRESENTATIVE PARTICLES (RP)

Name of RPs Number of FPs

Fe Atom 1 atom

Fe2O3 Formula unit (Fe2O3)Ion (Fe3+ and O2-)

1 formula unit2 Fe3+ ions and 3 O2- ions

5 CO2 Molecule (CO2)Atom (C and O)

5 molecules5 C atoms and 10 O atoms

3 Zn

4 N2O4

2 Ca3P2

Name of RPs Number of FPs

Fe Atom 1 atomFe2O3 Formula unit

(Fe2O3)Ions (Fe3+ and O2-)

1 formula unit2 Fe3+ ions and 3 O2- ions

5 CO2 Molecule (CO2)Atom (C and O)

5 molecules5 C atoms and 10 O atoms

3 Zn Atom 3 Zn atoms4 N2O4 Molecule; Atom 4 molecules

8 N atoms, 16 O atoms

2 Ca3P2 Formula unit; Ions

2 formula units6 Ca2+ ions6 P3- ions

MOLE CONVERSIONS #1: MOLES RP 1 MOLE = 6.02 X 1023

How many atoms are in 0.150 moles of Co?

9.03 x 1022 atomsHow many formula units are in 12.07 moles of Na2O?

7.266 x 1024 formula units

MOLE CONVERSIONS #1: MOLES RP 1 MOLE = 6.02 X 1023

How many Na+ IONS are in 12.07 moles of Na2O?

1.453 x 1025 ionsYou Do: How many O atoms are in 0.075 moles of NaNO3 ?

MOLE CONVERSIONS #1: MOLES RP 1 MOLE = 6.02 X 1023

How many Na+ IONS are in 12.07 moles of Na2O?

1.453 x 1024 ionsYou Do: How many O atoms are in 0.075 moles of NaNO3 ?

1.4 x 1023 atoms of O

MOLE CONVERSIONS #1: RP MOLES 1 MOLE = 6.02 X 1023

You Do: How many moles is 5.07 x 1023 atoms of Zr?

You Do: How many moles is 8.90 x 1024 molecules of CO2?

MOLE CONVERSIONS #1: RP MOLES 1 MOLE = 6.02 X 1023

You Do: How many moles is 5.07 x 1023 atoms of Zr?

0.842 moles of ZrYou Do: How many moles is 8.90 x 1024 molecules of CO2?

14.8 moles of CO2

WHAT ABOUT MASS THEN?Remember the “gaggle” of Cheerios? (1 “gaggle” = 100 Cheerios = 15.0 g)? Similarly, you need to know the mass of one mole of the chemical in order to convert to mass. This is also known as “molar mass.”

You have to know this because one mole of a chemical CAN weigh differently compared to another, but they have the same NUMBER of RP’s.

WAIT… WHAT DOES THE PERIODIC TABLE HAVE TO DO WITH THE MOLE?The mass of one copper atom is 63.546 amu (atomic mass units)(1 amu = 1/12th the mass of one carbon-12 atom)(1 amu = 1.6605 x 10-27 kg)

1.What is the mass of one copper atom in kg?

2.Convert this mass to grams.3.Multiply the mass of one copper atom in

grams by 6.022 x 1023.

What do you notice?What is the meaning of 63.546?

 

Molecular Mass of a covalent compound is the (atomic) mass of one molecule. H2O = H 2 x 1.01 = 2.02 g O + 1 x 15.99 = 15.99 g

18.01 g/molCalculate the molar (molecular) mass of CH4 (methane)

CH4 =    

Formula Mass of an ionic compound is the (atomic) mass of one formula unit.NaCl = 22.99 + 35.45 = 58.44 g/molMnCl2 = 54.94 + 70.90 (2 mol Cl) = 125.84 g/mol

Let’s make it harder… what is the formula mass of Ca(NO3)2 ?(yes… that’s 1 Ca, 2 N’s, and 6 O’s)

What is the formula mass of Mg3(PO4)2?

How do you determine the amount of moles in a compound? 1. If you have 9.0 grams of water, you have ____moles of water. Water - H2O = 18.01 g/mol

9.0 g H2O x 1 mole of H2O = 0.50 mol of H2O 18.01 g H2O

2. If you have 13.0 grams of water, you have ____moles of water.   

 

 0.722 moles of water   

 

 

 

If you weigh out 5.00g of formaldehyde (formula CH2O), how many moles is that?

0.166 molesWhat about 60.0 g of formaldehyde?

2.00 moles

Counting Moles 2 mol C6H12O6 contains:2 mole of C6H12O6 molecules2 x 6 = 12 moles of C atoms2 x 12 = 24 moles of H atoms2 x 6 = 12 moles of O atoms48 moles of atoms in total

Complete the rest of “Counting Atoms” for BF3 and Ca(NO3 )2.

 

FULL MOLE CONVERSIONS PROBLEMSALWAYS USE NA AND FORMULA OR MOLECULAR MASS

How many sodium ions are in 50.0 g of Na2S?

7.71 x 1023 sodium ions

FULL MOLE CONVERSIONS PROBLEMS

You do: What is the mass of 7.04 x 1023 molecules of PF5?

147 g of PF5

COMPLETE THE INDEPENDENT PRACTICEI’ll run around and check your work. Always use dimensional analysis and respect the sig fig rules.

A SUMMARY – THE “MOLE MAP”Be careful – “particles” usually means “molecules” or “formula units” unless the material is an element.

We will not calculate volume for now.

WHITEBOARDSGet a person in your group to get one whiteboard per person in your group and a bag of erasers and dry erase markers.

I want to see the dimensional analysis and the answer (with sig figs) for each question.

QUESTION 1How many atoms of potassium are in 2 moles of K2O? _______________________

QUESTION 1How many atoms of potassium are in 2 moles of K2O? _______________________

2 x 1024 potassium atoms

QUESTION 2How many molecules of water make up 5 MOLES? ________________________

QUESTION 2How many molecules of water make up 5 MOLES? ________________________

3 x 1024 molecules

QUESTION 3How many moles are 6.022 x 1023 atoms of sodium? ________________________

QUESTION 3How many moles are 6.022 x 1023 atoms of sodium? ________________________

1.000 moles

QUESTION 4How many grams are in 2.3 x 10-4 moles of calcium phosphate, Ca3(PO3)2?

QUESTION 4How many grams are in 2.3 x 10-4 moles of calcium phosphate, Ca3(PO3)2?

0.12 grams

QUESTION 5How many oxygen atoms are in 3.4 x 10-7 grams of silicon dioxide, SiO2?

QUESTION 5How many oxygen atoms are in 3.4 x 10-7 grams of silicon dioxide, SiO2?

6.8 x 1015 oxygen atoms

SONG BREAK

https://www.youtube.com/watch?v=PvT51M0ek5c

“A Mole is a Unit”

EXIT TICKET

What did you learn today about the mole and mole conversions?