What do I know about moles? What do I want to know about moles? What have I learned about moles...

KWL CHART--MOLESWhat do I know about moles?

What do I want to know about moles?

What have I learned about moles today?

MOLES This unit test contains 6 types of

problems:1. Molar mass and % composition—must

be able to write a chemical formula2. Grams to moles (using molar mass)3. Moles to particles/atoms/molecules

(using Avogadro’s #)4. Grams to moles to particles (using

molar mass and Avogadro’s #)5. Empirical formulas6. Molecular formulas

MOLE

The SI (metric) unit used to measure the amount of a substance

1 mole is always equal to:--Molar mass (g/mole)--Avogadro’s number of particles (6.02 x

1023)--22. 4 Liters of a GAS (AKA molar volume)

These may be used as conversion factors when working mole problems.

ACTIVATOR

Define molar mass AND Avogadro’s number.

1 mole of this substance

# of atoms/molecules/particles

Mass of 1 mole (molar mass) g/mole

Volume of 1 mole

table sugar (sucrose)--C12H22O11

342.0

Sodium chloride--NaCl

58.5

Cupric sulfate--CuSO4

159.6

Sulfur--S 32.1Iron--Fe 55.8

Water—H2O 18.0

MOLAR MASS OF ELEMENTS—SAME AS ATOMIC MASS Ex: Titanium 47.867 = 47.9 g/mole

(this sample contains Avogadro’s number of atoms)

Ex: oxygen 15.999 = 16.0 g/mole(this sample contains Avogadro’s number

of atoms)

MOLAR MASS OF COMPOUNDS—MUST WRITE CHEMICAL FORMULA CORRECTLY Multiply the # of atoms for each element by

the atomic mass from periodic table

Ex:Magnesium hydroxideMg (OH)2

Mg 1(24.3) = 24.3O 2(16.0) = 32.0H 2(1.0) = 2.0

58.3 g/mole (this mass also contains Avogadro’s number of

molecules)

Find the molar mass of aluminum sulfate

Al 2 (SO4)3

Al 2(27.0) = 54.0S 3 (32.1)= 96.3O 12(16.0) = 192.0

342.3 g/mole (this mass also contains Avogadro’s number of molecules)

Calculate the molar mass of diarsenic trioxide.

MOLAR MASS PRACTICE-- Stannic carbonate

Diarsenic pentasulfide

Hydrofluoric acid

ACTIVATOR: CALCULATE THE MOLAR MASS Sucrose

% COMPOSITION Shows the % of each element that makes up a

compound Must be calculate molar mass first.Ex: magnesium hydroxide Mg (OH)2

Mg 1 x 24.3 =24.3 24.3/58.3 x 100 = 41.7%

O 2 x 16= 32.0 32.0/58.3 x 100 = 54.9%

H 2x1.0 = 2.0 58. 3 g/mole

2.0/58.3 x 100 = 3.4%

ACTIVATOR: Calculate the % composition of sulfurous

acid

LAB—BITE THE BUBBLE SAVE YOUR WRAPPER FOR ENTIRE

LAB!!

DO NOT START CHEWING UNTIL YOU SIT DOWN BACK AT YOUR DESK.

CHECK BALANCE TO MAKE SURE IT’S OK BEFORE YOU START!!

READ PROBLEM:

MAKE A HYOTHESIS:

PROCEDURE 1—4

DATA TABLE 1—5

After chewing: (KEEP YOUR SAME BALANCE)

Procedure 5—8

Data table 6—8

Conclusion

Questions 1—2

Calculate the % composition for a sugar substitute called SUCRALOSE

C 12( 12.0) = 144.0 H 19 (1.0) = 19.0 Cl 3 (35.5) = 106.5 O 8 (16.0) = 128.0

397. 5 g/mole% C= 144.0 / 397.5 x 100 = 36.2%% H= 19.0 / 397.5 x 100 = 4.8%% Cl= 106.5 / 397.5 x 100 = 26.8%% O= 128.0/ 397.5 x 100 = 32.2%

TICKET OUT 1. Calculate the % composition of

carbonic acid.

2. Calculate the % composition of diantimony trioxide.

1. H2CO3

H-2 (1.0) = 2.0 3.2%C- 1 (12.0) = 12.0 19.4%O – 3(16.0) = 48.0 77.4%

62.0 g/mole

2. Sb2O3

Sb- 2(121.8) =243.6 83.5%O – 3(16.0) = 48.0 16.5%

291.6 g/mole

ACTIVATOR Calculate the molar mass AND %

composition of:

1. C12H22O11

2. Cupric sulfate

C: 12 (12.0) = 144.0 H: 22 (1.0) = 22.0 O: 11(16.0) = 176.0

CuSO4

Cu: 1(63.5)= 63.5S: 1 (32.1) = 32.1O: 4(16.0) = 64.0

CONVERTING GRAMS TO MOLESWill need to use unit

conversion(cancellation) and molar mass will be used for the conversion factor.

Ex: 2.50 grams of hydrochloric acid = ____moles

H Cl

2.50 grams x 1 mole = 0.0685 moles(3sigfigs)

36.5 grams

CONVERTING MOLES TO GRAMSEx: 2.50 moles of HCl = __________grams

2.5 moles x 36.5 grams = 91 grams 1 mole (2 sig figs)

CONVERTING PARTICLES TO MOLES Particles, atoms, molecules (synonyms)

Will have to use Avogadro’s number as a conversion factor

Ex: 5.25 x 1025 atoms of Mg = _____moles

5. 25 x 1025 atoms x 1 mole = 87.2 moles

6.02 x 1023 (3 sig figs)

CONVERTING MOLES TO PARTICLES2.50 moles MgO = _________molecules

2.50 moles x 6.02 x 1023 molecules 1 mole

= 1.50 x 1024 molecules (3 sig figs)

CONVERTING GRAMS TO PARTICLES Will need to use both molar mass AND

Avogadro’s number as conversion factors Will be 2 steps instead of 1 step unit cancellation

Ex: 4.5 grams nitrous acid = __________molecules

HNO2

4.5 g x 1 mole x 6.02 x 1023 molecules = 47 g 1 mole

5.8 x 1022 molecules (2 sig figs)

CONVERTING PARTICLES TO GRAMS Ex: 9.35 x 1021 particles of carbon

tetrabromide = _____grams

C Br4

9.35 x 1021 p x 1 mole x 154 grams = 6.02x1023 p 1 mole

2.39 grams (3 sig figs)

ANSWERS TO HOMEWORK: MUST SHOW WORK TO RECEIVE CREDIT

1. 0.14 mole (gram to moles)2. 150 g (moles to grams)3. 1.1 x 1023 molecules (g to molecules)4 5.30 x 1025 molecules (moles to

molecules)5. 0.074 mole( gram to moles)6. 0.619 g (particles to grams)7. 0.49 mole (grams to moles)8. 0.00083 mole (particles to moles)  

TAB 3 “EVEN MORE MOLE PROBLEMS”—SHOW WORK TO RECEIVE CREDIT

1. 22 g2. 1.53 x 1024 molecules3. 0.014 g4. 7.2 x 1021 molecules5. 7.2 x 1023 molecules6. 2.08 x 106 g7. 56 g8. 2.5 g9. 31 g10. 0.0029 mole11. 167 gBONUS: 3.37 x 1026 atoms

ACTIVATOR

If grams are converted to moles,use _______________ to convert.If moles are converted tomolecules, then use______________to convert.

****Have calculator, periodic table, and best friend chart****

MOLE GAMEAll members of your group must show

their work on separate sheet of paper.

When you calculate the answer, flip the card over to find a word.

All of your words will make a sentence.

First group to show all work and finish first, wins bonus!

MOLE PROBLEM DIAGRAM

Grams-----moles-----particles(atoms or molecules)

EXTRA PRACTICE-MOLE PROBLEMS1. 55.33 grams of sodium oxide =

____moles

2. 5.00 x 1022 particles of sodium= _______moles

3. 2.49 x 1026 atoms of acetic acid = _______________grams

HOMEWORK:

Video sheet Problems #1—3, 5, 6

ACTIVATOR:Fill in the blanks with multiply/divide

OR molar mass/Avogadro’s number:

***When going from moles to grams, _______________ by _____________.

***When going from moles to particles, ____________by _________________.

I AM CHECKING 5 HOMEWORK PROBLEMS!!!!

TICKET OUT

Briefly describe the steps for calculating an empirical formula AND molecular formula.

ACTIVATOR

Define empirical formula

***both labs due today***

MOLE REVIEW PROBLEMS

1. Convert 5.03 x 1024 molecules of phosphoric acid to grams.

2. Convert 35.75 grams of dinitrogen monoxide to moles.

3. Convert 5.0 moles of water to molecules.

ANSWERS1. 819 grams of H3PO4

2. 0.8125 moles of N20

3. 3.0 x 1024 molecules of water

TICKET OUT

Tell how to solve for each:1. G to moles2. Moles to G3. Particles to moles4. Moles to particles5. G to particles6. Particles to G

GUM LAB—SHOW WORK TO RECEIVE CREDIT

HYPOTHESIS, DATA 1—8, CONCLUSION, QUESTIONS 1—4

3. MASS OF SUGAR (in grams—data #8)--------MOLES(SUGAR = C12 H22 O11)

  4. MOLES----------PARTICLES

LAB-USING THE MOLE Data Table: mass of empty vial AND

substances mass (make sure you’ve subtracted empty vial each time!!)

  SHOW WORK TO GET CREDIT

CONVERT GRAMS----------MOLES CONVERT MOLES---------PARTICLES ANSWER QUESTIONS 1---5, 6 (BONUS)

ACTIVATOR:

Convert 25.0 moles of water to grams.

ACTIVATOR

A molecular formula is a whole number____________of the empirical formula.

EMPIRICAL FORMULAS Shows the SIMPLEST, WHOLE NUMBER

ratio of elements in a compound

Will give you % composition of compound and ask you to find the formulas

STEPS FOR CALCULATING:1. Change % sign to grams (some problems

may already give you grams instead of %)

2. Convert grams to moles (using molar mass)**round to 4 decimals***

3. Simplify the mole ratio by dividing each one by the smallest

4. Round to the nearest whole number and assign these numbers to the appropriate element

EXAMPLE:A compound is 78.1% Boron and 21.9% H.

Calculate the empirical formula.78.1 grams B x 1 mole = 7.2315 moles B

10.8 g21.9 grams H x 1mole =21.9 moles H

1.0 g7.2315 : 21.97.2315 7.2315

1: 3 = BH3

MOLECULAR FORMULAS:Is a WHOLE NUMBER MULTIPLE of the

empirical formula

You must then first know the empirical formula

STEPS FOR CALCULATING:1. You must first have empirical formula (if not,

you will have to calculate it first!!)

2. Find the molar mass of the empirical formula.

3. Take the molar mass of the molecular formula that is given in the problem divided by the empirical formula’s molar mass. Round this to a whole number.

4. Distribute this number to the numbers within the empirical formula to get the new molecular formula.

EXAMPLE: 1Given the empirical formula of BH3 and

the molecular formula’s molar mass of 27.67 g/mole, find the molecular formula.

Molar mass of BH3 is 13.8 g/mole

27.67 divided by 13.8 = 2

So molecular formula is B2H6

EXAMPLE: 2A compound is 4.04 grams of nitrogen and 11.46

grams of oxygen. The molecular molar mass is 108.0 g/mole. Find the molecular formula.

4.04 g N x 1 mole= 0.2886 mole N14.0 g

11.46 g O x 1 mole =0.7163 mole O16.0 g

0.2886 : 0.71630.2886 0.28861: 2 = NO2 empirical molar mass = 46.0 g/mole

108.0 divided by 46.0 = 2Molecular formula = N2O4