The Mole. 6.02 X 10 23. The Mole. A counting unit Similar to a dozen, except instead of 12, it’s 602 billion trillion 602,000,000,000,000,000,000,000 6.02 X 10 23 (in scientific notation)
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6.02 X 1023
Suppose we invented a new collection unit called a rapp. One rapp contains 8 objects.
1. How many paper clips in 1 rapp?
a) 1 b) 4 c) 8
2. How many oranges in 2.0 rapp?
a) 4 b) 8 c) 16
3. How many rapps contain 40 gummy bears?
a) 5 b) 10 c) 20
usually we round to the tenths place
B. MolarMass of antacid Al(OH)3 = ? Grams/mole
Prozac, C17H18F3NO, is a widely used antidepressant that inhibits the uptake of serotonin by the brain. Find its molar mass.
Note that the NUMBER is always the same, but the MASS is very different!
Mole is abbreviated mol (gee, that’s a lot quicker to write, huh?)
1 mole C
1 mole H2O
1 mole NaCl
= 6.02 x 1023 C atoms
= 6.02 x 1023H2O molecules
= 6.02 x 1023NaCl “molecules”
(technically, ionics are compounds not molecules so they are called formula units)
6.02 x 1023 Na+ ions and
6.02 x 1023Cl– ions
Unitary rates can be inverted when needed
6.02 x 1023 particles
6.02 x 1023 particles
Note that a particle could be an atom OR a molecule!
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
2. Conversion factors for Al
27.0g Al or 1 mol Al
1 mol Al 27.0 g Al
3. Setup3.00 moles Al x 27.0 g Al
1 mole Al
Answer = 81.0 g Al
1. Number of atoms in 0.500 mole of Al
a) 500 Al atoms
b) 6.02 x 1023 Al atoms
c) 3.01 x 1023 Alatoms
2.Number of moles of S in 1.8 x 1024 S atoms
a) 1.0 mole S atoms
b) 3.0 mole S atoms
c) 1.1 x 1048 mole S atoms
The artificial sweetener aspartame (Nutra-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?
molar mass Avogadro’s numberGrams Moles particles
Everything must go through Moles!!!
Find molar mass of C2H5OH
2 Carbon 2 x 12.011 g/mol = 24.022 g
6 Hydrogen 6 x 1.00795 g/mol = 6.0477 g
1 Oxygen 1 x 15.9994 g/mol = 15.9994 g
Molar mass = 46.0691 g/mol
1 carbon = 1 x 12.011 g/mol = 12.011 g
2 oxygen =2 x 15.9994 g/mol = 31.9988 g
How many atoms of Cu are present in 35.4 g of Cu?
35.4 g Cu 1 mol Cu 6.02 X 1023 atoms Cu 63.5 g Cu 1 mol Cu
= 3.4 X 1023 atoms Cu
How many atoms of K are present in 78.4 g of K?
What is the mass (in grams) of 1.20 X 1024 molecules of glucose (C6H12O6)?
How many atoms of O are present in 78.1 g of oxygen?
78.1 g O2 1 mol O2 6.02 X 1023molecules O2 2 atoms O 32.0 g O2 1 mol O2 1 molecule O2
Total 11.1 + 88.8 100 %
What is the percent carbon in C5H8NO4 (the glutamic acid used to make MSG monosodium glutamate), a compound used to flavor foods and tenderize meats?
a) 8.22 %C
b) 24.3 %C
c) 41.1 %C
The empirical formula of a compound is the smallest whole number ratio of the number of atoms of each element in the substance.
require mole ratios so convert grams to moles
moles of N = 2.34g of N = 0.167 moles of N
moles of O = 5.34 g = 0.334 moles of O
FeS1.5x 2 = Fe2S3What is the empirical formula of a compound which contains 53.73g of Fe and 46.27g of S?
=0.9621273 mole Fe
=1.4429614 mole S
2.381339 mole O= 3.0 O 0.7921162 mole S S
Na2SO3What is the empirical formula for sodium sulfite if it contains 36.5g sodium, 25.4 g sulfur and 38.1 g oxygen?
=1.587662 mole Na
=0.7921162 mole S
=2.381339 mole O
H2OWhat is the formula of a compound with 11.1 % Hydrogen and 88.9 % Oxygen?
= 11.0125602714 moles H
= 5.5564836719 mole O
The molecular formula is the actual ratio of atoms in a compound.
The molar mass of “HC” is 13.01894 gA compound contains 92.25% carbon and 7.75% hydrogen. The molecular mass is 78 g. What is the molecular formula?
7.68895 moles H= 1.0 H
7.680459 moles C C
= 7.680459 moles C
=7.68895 moles H
6 x CH =C6H6
The molecular mass of an oxide of nitrogen is 216 g. The compound contains 4.02 g of nitrogen and 11.48 g of oxygen. What is the molecular formula?
0.7175269 mole O= 2.5 O
0.2870055 mole N N
NO2.5X 2 = N2O5
N2O5= 108.0 g
=0.2870055 mole N
2 X N2O5 = N4O10
=0.7175269 mole O
Liters of gas at STP
Standard Molar Volume
Definition of mole
Mole RatioHow many atoms of hydrogen are in 138.56 L of CH4 (methane) at STP?
Standard Molar Volume
Mole RatioHow many grams of nitrogen are in 24.3 L of ammonia , NH3, at STP?
- the study of the quantitative aspects of chemical reactions.