Kwl chart moles
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Kwl chart--moles. MOLES. This unit test contains 6 types of problems: Molar mass and % composition—must be able to write a chemical formula Grams to moles (using molar mass) Moles to particles/atoms/molecules (using Avogadro’s #)

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Kwl chart moles

Kwl chart--moles


Moles

MOLES

  • This unit test contains 6 types of problems:

  • Molar mass and % composition—must be able to write a chemical formula

  • Grams to moles (using molar mass)

  • Moles to particles/atoms/molecules (using Avogadro’s #)

  • Grams to moles to particles (using molar mass and Avogadro’s #)

  • Empirical formulas

  • Molecular formulas


Kwl chart moles

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

activator

  • Define molar mass AND Avogadro’s number.


Molar mass of elements same as atomic mass

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

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 hydroxide

    Mg (OH)2

    Mg 1(24.3) = 24.3

    O 2(16.0) = 32.0

    H 2(1.0) = 2.0

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


Kwl chart moles

  • Find the molar mass of aluminum sulfate

    Al 2 (SO4)3

    Al 2(27.0) = 54.0

    S 3 (32.1)= 96.3

    O 12(16.0) = 192.0

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


Kwl chart moles

  • Calculate the molar mass of diarsenic trioxide.


Molar mass practice

MOLAR MASS PRACTICE--

  • Stannic carbonate

  • Diarsenicpentasulfide

  • Hydrofluoric acid


Activator calculate the molar mass

ACTIVATOR: calculate the molar mass

  • Sucrose


Composition

% 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%


Activator1

ACTIVATOR:

  • Calculate the % composition of sulfurous acid


Lab bite the bubble

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!!


Kwl chart moles

  • READ PROBLEM:

  • MAKE A HYOTHESIS:

  • PROCEDURE 1—4

  • DATA TABLE 1—5


Kwl chart moles

  • After chewing: (KEEP YOUR SAME BALANCE)

  • Procedure 5—8

  • Data table 6—8

  • Conclusion

  • Questions 1—2


Kwl chart moles

  • Calculate the % composition for a sugar substitute called SUCRALOSE


Kwl chart moles

  • 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

Ticket out

  • 1. Calculate the % composition of carbonic acid.

  • 2. Calculate the % composition of diantimony trioxide.


Kwl chart moles

  • 1. H2CO3

    H-2 (1.0) = 2.0 3.2%

    C- 1 (12.0) = 12.019.4%

    O – 3(16.0) = 48.077.4%

    62.0 g/mole

  • Sb2O3

    Sb- 2(121.8) =243.683.5%

    O – 3(16.0) = 48.016.5%

    291.6 g/mole


Activator2

ACTIVATOR

  • Calculate the molar mass AND % composition of:

  • C12H22O11

  • Cupric sulfate


Kwl chart moles

  • C: 12 (12.0) = 144.0

  • H: 22 (1.0) = 22.0

  • O: 11(16.0) = 176.0

    CuSO4

    Cu: 1(63.5)= 63.5

    S: 1 (32.1) = 32.1

    O: 4(16.0) = 64.0


Converting grams to moles

Converting Grams to moles

Will 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 grams

Converting moles to grams

Ex: 2.50 moles of HCl = __________grams

2.5 moles x 36.5 grams = 91 grams

1 mole (2 sig figs)


Converting particles to moles

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 particles

Converting moles to particles

2.50 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

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 g1 mole

    5.8 x 1022 molecules (2 sig figs)


Converting particles to grams

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

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

Tab 3 “even more mole problems”—show work to receive credit

  • 22 g

  • 1.53 x 1024 molecules

  • 0.014 g

  • 7.2 x 1021 molecules

  • 7.2 x 1023 molecules

  • 2.08 x 106 g

  • 56 g

  • 2.5 g

  • 31 g

  • 0.0029 mole

  • 167 g

    BONUS: 3.37 x 1026 atoms


Activator3

activator

If grams are converted to moles,

use _______________ to convert.

If moles are converted to

molecules, then use

______________to convert.

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


Mole game

Mole game

All 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

Mole problem diagram

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


Extra practice mole problems

Extra practice-mole problems

  • 55.33 grams of sodium oxide = ____moles

  • 5.00 x 1022 particles of sodium= _______moles

  • 2.49 x 1026 atoms of acetic acid = _______________grams


Homework

Homework:

Video sheet Problems #1—3, 5, 6


Activator4

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 out1

Ticket out

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


Activator5

activator

Define empirical formula

***both labs due today***


Mole review problems

Mole review problems

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

  • Convert 35.75 grams of dinitrogen monoxide to moles.

  • Convert 5.0 moles of water to molecules.


Answers

answers

  • 819 grams of H3PO4

  • 0.8125 moles of N20

  • 3.0 x 1024 molecules of water


Ticket out2

Ticket out

Tell how to solve for each:

  • G to moles

  • Moles to G

  • Particles to moles

  • Moles to particles

  • G to particles

  • Particles to G


Gum lab show work to receive credit

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

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)


Activator6

Activator:

Convert 25.0 moles of water to grams.


Activator7

activator

A molecular formula is a whole number____________of the empirical formula.


Empirical formulas

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

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

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 g

21.9 grams H x 1mole =21.9 moles H

1.0 g

7.2315 : 21.9

7.2315 7.2315

1: 3 = BH3


Molecular formulas

Molecular formulas:

Is a WHOLE NUMBER MULTIPLE of the empirical formula

You must then first know the empirical formula


Steps for calculating1

Steps for calculating:

  • You must first have empirical formula (if not, you will have to calculate it first!!)

  • Find the molar mass of the empirical formula.

  • 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.

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


Example 1

Example: 1

Given 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 2

Example: 2

A 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 N

14.0 g

11.46 g O x 1 mole =0.7163 mole O

16.0 g

0.2886 : 0.7163

0.28860.2886

1: 2 = NO2 empirical molar mass = 46.0 g/mole

108.0 divided by 46.0 = 2

Molecular formula = N2O4


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