Conversion Practice Name



Conversion Practice Name ___________________________________

Show all work, round to the nearest hundredth, show proper units Date __________________________ Per ______

HOW TO FIND MOLAR MASS

Ex 1: CO2

1_ mol C x 12.01__ g = 12.01 g/mol

2_mol O x 16.00___g = 32.00 g/mol

Answer =

Your turn: Calculate the molar mass for the following compounds. Show all work and include proper units. You will use these answers for the conversion problems below.

1. Ca3N2 2. Al(OH)3

3. Fe2O3 4. H2O

HOW TO FIND MOLES WHEN GIVEN MASS (GRAMS)

given grams 1 mole = answer moles (mol)

grams

(This is molar mass)

Ex 2: Calculate the number of moles in 2.5g of CO2.

2.5g of CO2 1 mol CO2 = 00000

g

5.) Your turn: Calculate the number of moles in 235.00g of Ca3N2

=

HOW TO FIND MASS (GRAMS) WHEN GIVEN MOLES:

given moles grams (again, this is molar mass) = answer grams (g)

1mole

Ex 3: How many grams are in 7.25 moles of CO2 ?

7.25 moles of CO2 44.01 g CO2 = 319.07 g

1 mol CO2

6.) Your turn: How many grams are in 3.12 x 103 moles of Al(OH)3?

=

HOW TO FIND REPRESENTATIVE PARTICLES (ATOMS, MOLECULES, FORMULA UNITS , IONS) WHEN GIVEN MOLES:

Given moles 6.02 x 1023 particles =

1 mole

Ex 4: How many molecules of CO2 are in 14 moles of CO2?

14 moles CO2 6.02 x 1023 molecules CO2 = 8.43 x 1024 molecules CO2

1 mol CO2

7.) Your turn: How many molecules of H2O are in 6.98 x 104 moles of H2O?

=

HOW TO FIND MOLES WHEN GIVEN REPRESENTATIVE PARTICLES (ATOMS, MOLECULES, IONS, FORMULA UNITS)

Given particles 1 mole = answer in moles (mol)

6.02 x 1023 particles

Ex 5: How many moles of C (Carbon) are in 3.4 x 1023 atoms of C (Carbon) ?

3.4 x 1023 atoms C 1 mole C = 0.56 mol C

6.02 x 1023 atoms C

8.) Your turn: How many moles are in 1.33 x 1039 formula units of Fe2O3?

HOW TO FIND REPRESENTATIVE PARTICLES (ATOMS, MOLECULES, IONS, FORMULA UNITS) WHEN GIVEN MASS (GRAMS):.

Given grams 1 mole 6.02 x 1023 particles =

(molar mass) grams 1 mole

Ex 6: How many molecules of CO2 are in 355 g of CO2?

355 g CO2 1 mole CO2 6.02 x 1023 molecules CO2 = 4.86 x 1024 atoms CO2

44.01 g CO2 1 mole CO2

9.) Your turn: How many formula units are in 244.86 g Al(OH)3?

=

HOW TO FIND MASS (GRAMS) WHEN GIVEN REPRESENTATIVE PARTICLES (ATOMS, MOLECULES, ION, FORMULA UNITS):

given particles 1 mole (molar mass) grams = Answer in grams

6.02 x 1023 particles 1 mole

Ex 7: How many grams are in 9.20 x 1027 molecules of CO2?

9.20 x 1027 molecules of CO2 1mole CO2 44.01 g CO2 = 6.73 x 105 g CO2

6.02 x 1023 molecules CO2 1 mole CO2

10.) Your turn: How many grams are in 3.38 x 1022 formula units of Fe2O3?

=

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Atomic mass from the periodic table.

Steps for finding molar mass:

1. Separate each element from the formula

2. Identify the number of moles per element

3. Multiply the number of moles of each element by their atomic

mass from the periodic table

4. Add the numbers and include the unit: g/mol

44.01 g/mol

This is the number of moles for this element

This is your final answer, the molar mass.

This is your given grams

You get this answer by dividing the top number by the bottom number, so 2.5 divided by 44.01

0.06 mol

44.01 g CO2

This is the molar mass that was calculated in example 1

This is your given moles

This is the molar mass of CO2 which was calculated in example 1

You get this answer by multiplying the two numbers that are side by side So 7.25 x 44.01

Use Avogadro’s number here

Answer in molecules, atoms, or formula units. Depends on what word is used in the question

To get the answer, you would have to multiply 14 by 6.02 x 1023

To get the answer, you would have to divide 3.4 x 1023 atoms CO2 by 6.02 x 1023

Answer in molecules, atoms, or formula units. Depends on what word is used in the question

To get the answer, multiply 355 by 6.02 x 1023 and divide that answer by 44.01

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