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AU / Chemistry / CHEM 1030 / Given that the molar mass of a compound is 92 g/mol, determine the mol

Given that the molar mass of a compound is 92 g/mol, determine the mol

Given that the molar mass of a compound is 92 g/mol, determine the mol

Description

School: Auburn University
Department: Chemistry
Course: Fundamentals Chemistry I
Professor: John gorden
Term: Fall 2015
Tags:
Cost: 25
Name: Chapter 5 Lecture Notes
Description: These notes cover chapter 5 lecture. If it would be helpful, I can make online flashcards for the items needed to be memorized, but they are listed in the textbook.
Uploaded: 10/19/2016
6 Pages 74 Views 8 Unlocks
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Chapter 5 Lecture Notes CHEM 1030 Rik Blumenthal


What is nomenclature?



∙ Ionic Compounds and Ionic Bonding

o Ionic compounds form when cations (atoms with positive charge) and  anions (atoms with negative charge) combine.

 Ex. NaCl

Na (sodium) is a cation

Cl (chlorine) is an anion

When combined, the single electron from sodium completely transfers  to chlorine, a process called ionization

o Ionic compounds denoted in  

chemical formulas (show elements in ration in which they combine)  Ex. Li + O  Li2O

Notice that Li has one valence electron and O has two valence  

electrons.

 SO We also discuss several other topics like Discrimination means what?

To be electrically neutral, Li must appear in two.


What are the list of ions?



o The structural arrangement of ionic compounds are appear in a lattice structure

∙ Ionization, the addition of electrons to an atom, requires energy.  That energy is called lattice energy (amount of energy required to convert a mole of an ionic  

solid to the gas phase).

o Lattice energy is a measure of a compound’s stability

 Lattice energy increases with electronegativity

Stability increases with electronegativity

Higher Lattice Energy = More Stable Compound We also discuss several other topics like What is bodhgaya?

∙ Naming Ions and Ionic Compounds

o Nomenclature is the process of naming compounds

o For naming monatomic ions, add the word “ion” to the element name  Ex. K+ is potassium ion  


What is the organic compounds?



If you want to learn more check out What are the different approaches to pricing?

 Ex. Na+ sodium ion

o Transition metals sometimes have multiple charges.

For those, we use the stock system which uses roman numerals  Ex. Iron

 Fe2+ = iron (II) ion

 Fe3+ = iron (III) ion

o List of ions with multiple charges (because these have multiple  charges, use roman numerals to notate number of atoms of each  element)

1. Scandium

Chapter 5 Lecture Notes CHEM 1030 Rik Blumenthal

2. Titanium

3. Vanadium  

4. Chromium Manganese

5. Iron

6. Cobalt

7. Nickel

8. Copper

9. Zinc

o For naming monatomic cations, change the end of the element  name to “-ide” and add the word “ion.”

 Ex. Cl- = chloride ion

 Ex. O- = oxide ion Don't forget about the age old question of Buddha means what?

∙ Formulas of Ionic Compounds

o To be electrically neutral, the sum of the charges must equal zero. If the charges are different, write the subscript for the cation  Don't forget about the age old question of What causes atmospheric stability?

numerically equal to the anion (and vice versa)

 Ex. Potassium bromide

 K+ + Br- KBr We also discuss several other topics like What are examples of contra revenue accounts?

 Ex. Zinc iodide

 Zn2+ + I-  ZnI2

 Ex. Aluminum oxide

 Al3+ + O2+  Al2O3

∙ Naming Ionic Compounds

o Name the cation followed by the anion with the ending “-ide” but  without the word “ion.”

 SEE ABOVE EXAMPLES

∙ Covalent Bonding and Molecules

o Electrons are shared instead of transferred

o Occurs between atoms of similar electronegativity

o Molecular Formulas: show exact number of atoms of each element  in the molecule

o Empirical Formulas: tells what whole number ratio elements  combine in

 Ex. Hydrogen peroxide: H2 O2

Empirical formula: HO

∙ Naming Molecular Compounds

o Name the first element

o Name the second element and change the ending to “-ide”

 Ex. HCl = hydrogen chloride

o If need be, specify the numbers of the atoms using Greek suffixes  Mono – 1

 Di – 2

 Tri – 3

 Tetra – 4

 Penta – 5

 Hexa – 6

 Hepta – 7

 Octa – 8

Chapter 5 Lecture Notes CHEM 1030 Rik Blumenthal

 Nona – 9

 Deca – 10

∙ Ex. SO2 = sulfur dioxide

(Notice that “mono” is ignored if it is for the first element,  

but it is used if for the second element)

∙ Naming Compounds Containing Hydrogen

o Put “hydrogen” first and change it to “hydro”

o Change “-ide” ending in the second element to “-ic”

 Ex. HCl = hydrochloric acid

∙ Covalent Bonding in Ionic Species

o Many ionic substances contain polyatomic ions (ions containing  multiple ions) held together by covalent bonding

o The chart on the next page is a list of all of the polyatomic ions we will  need to MEMORIZE for the test. The same table is on page 165 (Table  5.10) in our book. (I have no idea if he will actually ask for the names  of all of them, but he did say we would need to memorize them.)

Common Polyatomic Ions

Name

Formula/Charge

Cations

ammonium

NH4+

hydronium

H3O+

mercury (I)

Hg22+

Anions

acetate

C2H3O2-

azide

N3-

carbonate

CO32-

chlorate

ClO3-

chromate

CrO42-

Chapter 5 Lecture Notes CHEM 1030 Rik Blumenthal

cyanide

CN 

dichromate

Cr2O7-

dihydrogen phosphate

H2PO4-

hydrogen carbonate of

bicarbonate

HCO3-

hydrogen phosphate

HPO22-

hydrogen sulfate

HSO4-

hydroxide

OH 

hypochlorite

ClO 

nitrate

NO3-

nitrite

NO2-

oxalate

C2O42-

perchlorate

ClO4-

permanganate

MnO4-

peroxide

O22-

phosphate

PO43-

phosphite

PO33-

sulfate

SO42-

sulfite

SO32-

thiocyanate

SCN 

o Here are the rules to help you memorize the oxoanions

(polyatomic anions with one or more oxygen atoms) above  

polyatomic ions:

1. The ion with one more oxygen atom then the “- ate” ion  is “per…ate” ion.

 Ex. ClO3- is chlorate, so ClO4- is perchlorate

2. The ion with one less oxygen atom than the “- ate” ion

is chlorite.

 Ex. ClO3- is chlorate, so ClO2- is chlorite

3. The ion with two fewer oxygen atoms than the “- ate”  

ion is “hypo…ite” ion.

 Ex. ClO3- is chlorate, so ClO- is hypochlorite

o Here are some rules to help you memorize oxoacids (oxoanions  with a hydrogen attached):

1. An acid based on an “- ate” ion is “…ic acid.”

 Ex. ClO3- is chlorate, so HClO3 is chloric acid

I remember this with the phrase “I ate something icky.”

2. An acid based on “- ite” ion is called “…ous” acid.

 Ex. ClO2- is chlorite, so HClO2 is chlorous acid

3. Prefixes in oxoanions retain their name in the oxoacids.

Ex. ClO- is hypochlorite, so HClO- is hypochlorous acid

Chapter 5 Lecture Notes CHEM 1030 Rik Blumenthal

∙ Organic Compounds: compounds containing carbon

o Organic compounds are named based on the number of carbon atoms  they contain.

o Here is the chart from the page 163 (Table 5.8)

Formulas and Names of Alkanes (simple hydrocarbons)

Name

Formula

CH4

Methane

C2H6

Ethane

C3H8

Propane

C4H10

Butane

C5H12

Pentane

C6H14

Hexane

C7H16

Heptane

C8H18

Octane

C9H20

Nonane

C10H22

Decane

∙ Molecular and Formula Masses  

o We can use a compound’s molecular formula and atomic masses (from periodic table) to determine the molecular mass of a molecule.   Formula: Molecular Mass = ∑(number of atoms)(atomic  mass)

∙ Ex. Water H2O

MM = 2(1.001) + 1(15.999) = 18.001

o Percent Composition: we can also use the molecular formula to  calculate the percentage one element contributes to the total mass.  Formula: %mass of element = (mass of element)/(mass of  compound) x 100

∙ Ex. Water H2O

Let’s find the percent of hydrogen’s mass

%H = ( (2 x 1.001)/(2 x 1.001 + 15.999) ) x 100 = 5.926  

%H

o We can use the percent composition of an element to determine the  empirical formula (least common multiple of the ratios of atoms)and  the molecular formula (actual ratio that atoms appear in).

 Ex. Determine the empirical formula of a compound that is 30.45 %N and 69.55 %O.

1. Assume the mass percent equals the element masses.

30.45 %N = 30.45 g N

69.55 %O = 69.55 g O

2. Now, convert grams to moles

30.45 g N x 1 mol/14.01 g N = 2.173 mol N

69.55 g O x 1 mol/15.999 g O = 4.347 mol O

Chapter 5 Lecture Notes CHEM 1030 Rik Blumenthal

3. Now, divide the mole amount by the smallest of the two  

values to get the smallest possible whole numbers (these  

will end up being the subscripts in the empirical formula.)

2.173/2.173 = 1 mol

4.347/2.173 = 2 mol

Solution: NO2 is the empirical formula

It is important to note that we can’t find the actual molecular  

formula unless we are given the molar mass of the compound.  

Dr. Blumenthal didn’t do an example of this in class, here is how  you find the molecular formula:

Given that the molar mass of a compound is 92 g/mol,  

determine the molecular formula of a compound.

1. Divide the given molar mass by the empirical formula  

mass

Empirical Formula Mass = 14.001 + (2 x 15.999) = 46.01.

92/46.01 = about 2.

2. Now, multiply the subscripts in the empirical formula by 2

N2O4 is the molecular formula

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