6th Grade Lesson 23

1

NOTES Name: ______________________________________________ Date: ______________ Class: _____

Lesson 23: Molar Mass & Mass-Mole Conversions

Box 1:

1. How many atoms are in 0.0152 moles of Se?

2. How many moles are there if you have 6.040 x 1021 molecules of Na2SO4?

3. How many moles are there if you have 1.97 x 1028 atoms of Sb?

4. How many molecules are there in 7.111 moles of Sr3(PO4)2?

Box 2: Watch the video “How big is a mole?” and answer the following questions. https://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one#watch

1. Why do you think Chemists prefer to use the mole in Chemistry instead of counting each

particle?

2. How many molecules are in 18.01 mL of water?

3. If you have a balloon filled with one mole of gas at zero degrees Celsius at a pressure of one

atmosphere, how many gas particles do you have?

4. What is another name for the mole?

5. How big would a mole of basketballs be?

6th Grade Lesson 23

2

Molar Mass of Elements: The molar mass of an element is _________________________________

_____________________________.

The value is the ________________________________ on the Periodic Table,

and the units are in _______________________________________.

Find the molar mass of each element. Include units.

1. Na _________________________ 5. Li _________________________

2. O _________________________ 6. Ar _________________________

3. H _________________________ 7. Hg _________________________

4. Ca _________________________ 8. Ni _________________________

Additional Resources for you to Explore https://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one#digdeeper

A comprehensive biography of Avogadro can be found here: http://www.bulldog.u-net.com/avogadro/avoga.html The mole is taught in every introductory chemistry class one can take at the college level. Here's an example of a chemistry course: http://antoine.frostburg.edu/chem/senese/101/moles/index.shtml There is an entire day dedicated to commemorating Avogadro's Number. National Mole Day: http://www.moleday.org/ Sparknotes is a great resource for quick learning. You can explore all you ever wanted to know about chemistry here: http://www.sparknotes.com/chemistry/ "The primary unit for the amount of substance in a chemical element is the mole, and if you are talking about the stoichiometry of a reaction, the mole is the basis for that." Dr. Willie May, National Institute of Standards, Maryland

Element Average Atomic Mass (amu) Molar Mass (g/mol) Atoms / Mole

H 1.008 1.008 6.022 × 1023

O 16.00 16.00 6.022 × 1023

S 32.06 32.06 6.022 × 1023

Ga 69.723 69.723 6.022 × 1023

I 126.90 126.90 6.022 × 1023

Average atomic mass and molar mass are numerically equivalent, but they are VERY different in

terms of scale. The average atomic mass is in amu – representing the mass of a single atom. The

molar mass is in grams – representing the mass of 6.022 × 1023 atoms.

6th Grade Lesson 23

3

Molar Mass as a Conversion Factor: Molar mass can also be used as a conversion factor to

convert between mass (in grams) and moles.

CONVERTING BETWEEN MOLES AND MASS (ELEMENTS):

1. How many moles of He are there in 1.49g He?

2. How many moles of Sn are there in 1.49g Sn?

3. How many grams Si are there in 2.5 mol Si?

4. How many grams of In are there in 2.5 mol In?

Mass of

element in

grams

Amount of

element in

moles

Number of

atoms of

element

6th Grade Lesson 23

4

Molar Mass of Compounds:

The molar mass of a compound is the mass, in grams, of one mole of that compound.

It is calculated by adding up the molar masses of all of the elements in the compound.

Calculate the molar mass of each compound:

1. Li3P _________________________

2. Cs2CO3 _________________________

3. (NH4)2SO4 _________________________

4. MgCl2 _________________________

5. AsBr3 _________________________

6. NH4NO3 _________________________

7. Cr(PO4)2 _________________________

8. CaCl2 _________________________

Molar mass can also be used as a conversion factor to convert between grams and moles.

CONVERTING BETWEEN MOLES AND MASS (COMPOUNDS):

1. How many moles of H2O are there in 4.01g H2O?

2. How many moles of NaOH are there in 9.2g NaOH ?

6th Grade Lesson 23

5

3. How many grams K3P are there in 0.15 mol K3P ?

4. How many grams of Al2S3 are there in 21.5 mol Al2S3 ?

5. How many moles of GaN are there in 3.47g GaN?

6. How many moles of CO2 are there in 0.015g CO2?

Box 3:

Molar mass vs. Average atomic mass

6th Grade Lesson 23

6

Box 4: Definitions

Avogadro’s number: experimentally determined value of the number of entities comprising 1 mole of substance, equal to 6.022 × 1023 mol−1

concentrated: qualitative term for a solution containing solute at a relatively high concentration dilute: qualitative term for a solution containing solute at a relatively low concentration dissolved: describes the process by which solute components are dispersed in a solvent molar mass: mass in grams of 1 mole of a substance mole: amount of substance containing the same number of atoms, molecules, ions, or other entities as the number of atoms in exactly 12 grams of 12C solute: solution component present in a concentration less than that of the solvent solvent: solution component present in a concentration that is higher relative to other components

Advanced: Mass Mole Particle Conversions

Conversion factors can be used in sequence to directly convert between masses of substances and the

number of particles (atoms or molecules).

1. How many atoms of Cu are there in 4.56g Cu?

2. What is the mass in grams of 7.32 x 1019 atoms of Te?

3. What is the mass in grams of 4.9 x 1045 atoms of S?

6th Grade Lesson 23

7

EXTRA PRACTICE: CONVERTING BETWEEN MOLES AND NUMBER OF PARTICLES:

“PARTICLES”= atoms, compounds, or molecules

1. How many atoms is 12.6 moles of Sn?

2. How many moles is 5.022 x 1018 molecules of Li3PO4?

3. How many moles is 2.99 x 1024 atoms of Zn?

4. How many molecules is 3.440 moles of Sc3(PO4)2?

5. How many moles is 6.10 x 1015 molecules of KCN?

6. How many atoms is 0.0152 moles of Se?

7. How many moles is 1.97 x 1028 atoms of Sb?

6th Grade Lesson 23

8

EXTRA PRACTICE: CONVERTING BETWEEN MASS AND MOLES (ELEMENTS):

1. How many grams Mn are there in 3.11 mol Mn?

2. How many grams of Cs are there in 0.025 mol Cs?

3. How many moles of Ba are there in 13.54 g Ba?

4. How many moles of Se are there in 548.60 g Se?

5. How many grams Fe are there in 0.0091 mol Fe?

6. How many grams of Kr are there in 3.00 mol Kr?

6th Grade Lesson 23

9

EXTRA PRACTICE: CONVERTING BETWEEN MASS AND MOLES (COMPOUNDS):

1. How many grams MoO2 are there in 7.01mol MoO2?

2. How many grams of CaCO3 are there in 0.0352mol CaCO3?

3. How many moles of CoP are there in 9.40g CoP?

4. How many grams of SrCO3 are there in 0.0333mol SrCO3?

5. How many grams FeBr2 are there in 1.015mol FeBr2?

6. How many moles of GeO2 are there in 15.00g GeO2?

6th Grade Lesson 23

10

EXTRA PRACTICE: Advanced: Mass Mole Particle Conversions

1. What is the mass in grams of 2.69 x 1018 atoms of Se?

2. How many atoms of Ga are there in 4.25g of Ga?

3. What is the mass in grams of 4.11 x 1033 atoms of Al?

4. How many atoms of Ca are there in 148.9g Ca?

5. What is the mass in grams of 3.15 x 1019 atoms of Zn?

6. How many atoms of Fr are there in 168.95g of Fr?

6th Grade Lesson 23

11

Box 5:

Box 6:

Box 7:

6th Grade Lesson 23

12

Box 8:

Box 9:

Box 10: