Chemical Reactions and Chemical Reactions and QuantitiesQuantities

The MoleThe Mole

Calculations Using Molar MassCalculations Using Molar Mass

Collection Terms

1 trio = 3 singers

1 six-pack Cola = 6 cans Cola drink

1 dozen donuts = 12 donuts

1 gross of pencils = 144 pencils

A Mole of Particles

Contains 6.02 x 1023 particles

1 mole C = 6.02 x 1023 C atoms

1 mole H2O = 6.02 x 1023 H2O molecules

1 mole NaCl = 6.02 x 1023 Na+ ions and

6.02 x 1023 Cl– ions

More Examples of Moles

Moles of elements

1 mole Mg = 6.02 x 1023 Mg atoms

1 mole Au = 6.02 x 1023 Au atoms

Moles of compounds

1 mole NH3 = 6.02 x 1023 NH3 molecules

1 mole C9H8O4 = 6.02 x 1023 aspirin molecules

Avogadro's Number

6.02 x 1023 particles

1 mole

or

1 mole

6.02 x 1023 particles

22.4L1 mole

1 mole 22.4 L L

1 mole a.m.u.6.02 x 1023

1 mole

1 mole

6.02 x 1023

Using Avogadro’s Number

1. Number of atoms in 0.500 mole of Al1) 500 Al atoms

2) 6.02 x 1023 Al atoms3) 3.01 x 1023 Al atoms

2.Number of moles of S in 1.8 x 1024 S atoms1) 1.0 mole S atoms2) 3.0 mole S atoms3) 1.1 x 1048 mole S atoms

Solution

1. Number of atoms in 0.500 mol of Al3) 3.01 x 1023 Al atoms

2. Number of moles of S if a sample of S contains 4.50 x 1024 S atoms2) 3.0 mole S atoms

Molar Mass

Number of grams in 1 mole

Equal to the numerical value of the atomic

mass

1 mole of C atoms = 12.0 g

1 mole of Mg atoms = 24.3 g

1 mole of Cu atoms = 63.5 g

Molar Mass

Give the molar mass to 0.1 g

A. 1 mole of Br atoms = ________

B. 1 mole of Sn atoms = ________

Solution

Give the molar mass to 0.1 g

A. 1 mole of Br atoms = 79.9 g/mole

B. 1 mole of Sn atoms = 118.7 g/mole

Molar Mass of Compounds

Mass in grams of 1 mole equal numerically to the sum of the atomic masses

1 mole of CaCl2 = 111.1 g/mole

1 mole Ca x 40.1 g/mole

+ 2 moles Cl x 35.5 g/mole

1 mole of N2O4 = 92.0 g/mole

2 moles N x 14.0 g/mole + 4 moles O x 16.0 g/mole

Molar Mass

A. 1 mole of K2O = ______g

B. 1 mole of antacid Al(OH)3 = ______g

Solution

A. 1 mole of K2O = 94.2 g

2 K x 39.1 g/mole + 1 O x 16.0 g/mole

B. 1 mole of antacid Al(OH)3 = 78.0 g

1 Al x 27.0 g/mole + 3 O x 16.0 g/mole

+ 3 x 1.0

Percent Composition

What is the percent carbon in C5H8NO4 in

this compound that is used to flavor

foods and tenderize meats?

1) 8.22 %C

2) 24.3 %C

3) 41.1 %C

Solution

Molar mass = 146.0 g/mole

% = total g C x 100

total g compound

= 60.0 g C x 100 = 41.1% C

146.0 g MSG

Molar Mass Factors for CH4

Methane CH4 known as natural gas is used in gas cook tops and gas heaters. Express the molar mass of methane in the form of conversion factors.

Molar mass of CH4 = 16.0 g

16.0 g CH4 and 1 mole CH4

1 mole CH4 16.0 g CH4

Molar Mass

Acetic acid CH3COOH is the acid in vinegar . It

has a molar mass of 60.0 g/mole.

1 mole of acetic acid = ____________

1 mole acetic acid or g acetic acid g acetic acid 1 mole acetic acid

Solution

Acetic acid CH3COOH is the acid in vinegar . It

has a molar mass of 60.0 g/mole.

1 mole of acetic acid = 60.0 g

1 mole acetic acid or 60.0 g acetic acid 60.0 g acetic acid 1 mole acetic acid

Calculations with Molar Mass

molar mass

Grams Moles

Moles and Grams

Aluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al?

3.00 moles Al ? g Al

1. Molar mass of Al

1 mole Al = 27.0 g Al

2. Conversion factors for Al

27.0g Al or 1 mol Al

1 mol Al 27.0 g Al

3. Setup

3.00 moles Al x 27.0 g Al

1 mole Al

Answer = 81.0 g Al

Molar Mass

The artificial sweetener aspartame

(Nutri-Sweet) formula C14H18N2O5 is

used to sweeten diet foods, coffee and

soft drinks. How many moles of

aspartame are present in 225 g of

aspartame?

Solution

1. Molar mass of Aspartame C14H18N2O5

(14 x 12.0) + (18 x 1.01) + (2 x 14.0) + (5 x 16.0) = 294 g/mole

2. Setup

225 g aspartame x 1 mole aspartame

294 g aspartame

= 0.765 mole aspartame