MOLEChapter 10

DO NOW: Identify the number that each word refers to:

Couple - _______________ Dozen - _______________

Use dimensional analysis to solve the following problems.

a. A cake recipe requires 8 eggs. How many dozens of eggs are required to make 5 cakes?

BIG IDEAThe mole represents a large number of extremely small particles.

SECTION 1: MEASURING MATTER

ESSENTIAL QUESTIONS & VOCABULARY How is the mole used indirectly to count the number of particles of matter?

What is a common everyday counting unit that the mole can be related to?

How can moles be converted to number of representative particles and vice versa?

Vocabulary

Avogadro’s Number

Mole

Molecule

THE MOLE SI base unit used to measure the amount of substance.

1 mole = 6.022 x 1023

1 mole = 602,213,670,000,000,000,000,000

Abbreviated as mol

1 mole

THE MOLE IN PERSPECTIVE

1. One mole of paper would make a stack that would reach

to the moon more than 80 billion times

2. One mole of grains of sand would be more than all of

the sand on Miami Beach

3. One mole of blood cells would be more than the total

number of blood cells found in every human on earth

4. A one liter bottle of water contains 55.5 moles of

water

5. One mole of seconds is about 19 quadrillion years,

4,240,666 times the age of the earth, or 954,150

times the age of the universe itself

6. One mole of cents could repay the United States

National Debt 86 million times

THE MOLE IN PERSPECTIVE

MOLES TO PARTICLES

PARTICLES TO MOLES

MOLES & PARTICLESHow many molecules are in 3.0 moles of H2O?

How many moles of Aluminum, are in 4.02 x 1023 atoms of Al?

MASS AND THE MOLES

Section 2

ESSENTIAL QUESTIONS & VOCABULARY

Why can the mass of an atom be related to the mass of a mole of

atoms?

How can the number of moles be converted to the mass of an element

and vice versa?

How can the number of moles be converted to the number of atoms of

an element and vice versa?

Vocabulary

Conversion Factor

Molar Mass

MOLAR MASS:The mass of one mole of pure substance

Units are always expressed as grams per mole (g/mol)

Ex. Lithium = 6.94 g/mol

EXAMPLE: CALCULATE THE MOLAR MASS OF CH4

CALCULATE THE MOLAR MASS OF:Cu

NaCl

Ca2SO4

Al(NO3)3

MOLAR CONVERSIONS:

MOLES TO MASS

MASS TO MOLES How many moles of oxygen in 3.98 g of oxygen?

How many moles of carbon in 5.01 grams of carbon?

PRACTICE PROBLEM

Calculate the molar mass of Au (gold).

How many grams are in two moles of Au?

MOLES & MASSWhat is the mass of 3.0 mols of NaCl?

How many mols are in 30.0 g of H2O?

MOLES & PARTICLES & MASSCalculate the mass of 3.7 x 1024 molecules of MgCl2.

How many atoms are in 100.0g of Silver?

MOLES OF COMPOUNDS

Section 3

ESSENTIAL QUESTIONS & VOCABULARY

What are the mole relationships shown by a chemical formula?

How is the molar mass of a compound calculated?

How can the number of moles be converted to the mass of a compound and vice

versa?

What conversion factors are applied to determine the number of atoms in a

known mass of compound?

Vocabulary

Representative particle

CHEMICAL FORMULAS AND THE MOLE

Chemical formulas give the relative numbers of atoms or

moles of each element in a compound

Always a whole number ratio.

Example:

n determine the formula for the compound by knowing the

relative number of moles of each element in a compound.

EMPIRICAL AND MOLECULAR FORMULASSection 4

ESSENTIAL QUESTIONS & VOCABULARY

What is mean by the percent composition of a compound?

How can the empirical and molecular formulas for a compound be

determined from mass percent and actual mass data?

Vocabulary

Percent by mass

Percent composition

Empirical formula

Molecular formula

PERCENT COMPOSITIONPercent by mass of each element in a compound.

% composition of any pure substance is always constant,

whatever the source or sample size.

Useful in identifying the characteristic of any substance.

Used by investigators from many fields, Analytical

chemistry, forensics etc. to determine the identity of

unknown materials.

PERCENT COMPOSITIONRemember that percentage of anything is part over whole:

For elements in a compound, do mass of element over mass of compound.

SAMPLE PROBLEMSCalculate the percentage composition of each element in NaNO3. 27.05%Na, 16.48% N, 56.47% O

Calculate the percentage composition of Oxygen in Ag2SO4.

69.19% Ag, 10.28% S, 20.52% O

EMPIRICAL VS. MOLECULAR FORMULASEmpirical formulas – consists of the symbols for the

elements combined in a compound, with subscripts

showing the smallest whole-number ratio of the

different atoms in the compound.

Molecular Formulas – a multiple of the empirical

formula.

GUIDELINES FOR DETERMINING EMPIRICAL FORMULA

Determine the mass of each element

Convert into moles

Divide by the smallest mole or the elements present

Determine the ratio

Write the formula (Usually elements are listed from left to

right on the Periodic Table of Elements)

FINDING EMPIRICAL FORMULA – STEP 1 Determine the empirical formula of a compound that is composed of 36.5%

sodium, 25.4 % sulfur, and 38.1 % oxygen.

 STEP 1: Find the number of moles of each element present.Since the amount of each element is given in percentage, you must convert the percentage to a mass. If 100 grams of the sample are assumed, the percentages given are the same as grams.

FINDING EMPIRICAL FORMULA – STEP 2 & 3STEP 2: Determine the whole number mole ratio.Divide each mole number by the smallest mole number.

STEP 3: Use the mole ratio for the subscripts of each element in the formula.

 Na2SO3

EMPIRICAL FORMULA EXAMPLE 2

EMPIRICAL FORMULA: SAMPLE PROBLEMS

A compound is analyzed and found to contain 36.70% K, 33.27% Cl, and 30.03% O. What is the empirical formula of the compound?

A 60.00 g sample of tetramethyllead, a gasoline additive, is found to contain 38.46 g of lead, 17.82 of carbon, and hydrogen. Find its empirical formula.

FORMULAS OF HYDRATES

Section 5

ESSENTIAL QUESTIONS & VOCABULARY

What is a hydrate and how does its name relate to its

composition?

How is the formula of a hydrate determined from

laboratory data?

Vocabulary

Crystal lattice

hydrate

NAMING HYDRATES

NAMING HYDRATES

ANALYZING A HYDRATE

Must drive off the water by heating the compound

Substance remaining after heating is anhydrous (without

water)

Example: Hydrated cobalt (II) chloride is a pink solid that turns

a deep blue when the water of hydration is driven off and

anhydrous cobalt (II) Chloride is produced.

FORMULA FOR A HYDRATE

To determine the formula for a hydrate, you must

determine the number of moles of water associated

with one mole of the hydrate.

COPPER SULFATE HYDRATE EXAMPLE2.50 g CuSO4 · x H201.59 g CuSO4

0.91 g H20 (Hydrate – Anhydrous)

mol

0.01000.0100

=1𝑚𝑜𝑙𝐶𝑢𝑆𝑂4

CuSO4 · 5 H20

HYDRATES – COPPER SULFATE HYDRATE

USES OF HYDRATES

Drying Agents:

Storage of solar energy