Chemical Formulas and Chemical Compounds

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Chemical Formulas and Chemical Compounds

• Chapter 7

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Chemical Formulas

• Octane Molecule
• C8H18
• Aluminum Sulfate formula unit
• Al2(SO4)3

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Monatomic Ions

• Def ions formed from a single atom
• Naming ions
• Cation use element name
• Anion change ending of element to -ide

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Monatomic Ions

• d block elements and others with multiple ions
• Use Roman numeral in name
• Fe3 ? Iron(III) ion
• Fe2 ? Iron(II) ion
• Metals always have positive charge

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Polyatomic Ions
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Polyatomic Ions

• NO3- ? Nitrate
• NO2- ? Nitrite
• The ate means 1 more oxygen
• SO4-2 ? Sulfate
• SO3-2 ? Sulfite

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Polyatomic Ions

• ClO4- ? Perchlorate
• ClO3- ? Chlorate
• ClO2- ? Chlorite
• ClO - ? Hypochlorite

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Binary Ionic Compounds

• Def composed of 2 elements
• Total () charge must total (-) charge
• Write the formula
• Mg and Cl
• K and N
• Al and O

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Compounds with Polyatomic Ions

• Iron(II) and Nitrite
• Boron and Perchlorate
• Ammonium and Chlorine

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Naming Ionic Compounds

• Name the cation first, then the anion
• NaOH
• RbCl
• Ag2SO3
• Fe3N2
• CuMnO4

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Writing Formulas

• Potassium sulfide
• Copper(II) sulfate
• Sodium carbonate
• Calcium chloride
• Aluminum hydroxide

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Naming Binary Covalent Compounds

• CO, CO2
• We use PREFIXES in the name!!

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Prefixes
Mono- One Hexa- Six
Di- Two Hepta- Seven
Tri- Three Octa- Eight
Tetra- Four Nona- Nine
Penta- Five Deca- Ten
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Covalent Naming Rules

• Use prefixes to show how many of each element
• Single atom in first element, mono is not used
• The second element name ends in ide
• Drop vowel at end of prefix if element begins
  with vowel (except di and tri)

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Examples

• N2O4
• PCl5
• S3Br6
• Nitrogen Dioxide
• Boron Trifluoride
• Diphosphorus Pentoxide

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Naming Acids

• Begin with Hydrogen (H)
• 2 types of acids
• 1. Oxyacids
• hydrogen and polyatomic ion
• 2. Binary Acids
• w/o oxygen
• hydrogen and halogen CN-

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Naming Oxyacids

• Replace ending of anion name
• Anion Suffix Acid Suffix
• - ite - ous
• - ate - ic

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Naming Oxyacids

• H2SO4 ? anion SO4-2 ? Sulfuric Acid
• H2SO3
• HClO4
• HNO3

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Naming Oxyacids

• Acetic Acid
• Dichromic Acid
• Nitrous Acid

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Naming Binary Acids

• Use prefix hydro-
• Use suffix ic
• Followed by acid

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Naming Binary Acids

• HCl
• HF
• HI
• HBr
• HCN

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Relative Mass of Atom

• Mass of Oxygen-16 2.656 x 10-23 g
• Use relative atomic masses
• Pick standard ? other masses are expressed in
  relation to standard
• Standard Carbon 12 atom

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Carbon - 12

• Has mass of 12 atomic mass units (amu)
• 1 amu is exactly 1/12 the mass of a carbon-12
  atom
• Carbon-12 how many p and no?
• 1 p ? 1 amu (1.007276 amu)
• 1 no ? 1 amu (1.008665 amu)
• 1 e- ? 0 amu (0.005486 amu)

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Formula Mass

• Mass of H2O?
• Formula Mass mass of molecule, formula unit, or
  ion is sum of masses of all atoms represented
  (amu)
• Ca(NO3)2

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The Mole
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Groups

• 1 dozen
• 12
• 1 gross
• 144
• 1 ream of paper
• 500
• In chemistry 1 mole 6.022 x 1023

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The Mole

• SI unit for amount of substance (mol)
• Def the number of particles in exactly 12 g of
  carbon 12.
• 12 g of carbon 12 has 6.022 x 1023 atoms
• Avogadros , after Amadeo Avogadro
• The number is HUGE!!

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Molar Mass

• Def mass of 1 mole of a pure substance
• 1 mole Carbon 12 12 g
• 1 atom Carbon 12 12 amu
• Mass of 1 mole of He atoms?
• 4.00g
• Units g/mol
• Same as atomic mass from periodic table,
  different units

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Molar Mass

• Contains one mole of atoms
• So 4.00g He, 6.94 g Li and 200.59 g Hg all have
  the same of atoms
• 6.022 x 1023 atoms!!!
• Molar Mass (NH4)2CrO4?

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Molar Mass in Conversions

• Molar flow chart
• What is mass (g) of 3.04 mol of ammonia vapor,
  NH3?
• How many molecules are in 4.15 x 10-5g C6H12O6?

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More Conversions

• How many H atoms are in 7.1 moles of C6H12O6?
• How many formula units are in 4.5 kg Ca(OH)2?
• What is the mass of H2SO4, if you have 1.53 x
  1023 hydrogen ions in your compound?

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Percent Composition

• A basket of fruit 120 g
• 3 apples 50 g
• 2 oranges 35 g
• 2 bananas 20 g
• Basket 15 g
• What percentage of the baskets mass is from the
  apples?

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Percent Composition

• What is the percent composition by mass of each
  element in (NH4)2O?
• What percentage by mass of Al2(SO4)3?6H2O is
  water?

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Empirical Formula

• Def formula showing smallest whole-number mole
  ratio
• Ex B2H6 ? Molecular Formula
• BH3 ? Empirical Formula

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Finding Empirical Formula

• Determine the empirical formula of the compound
  with 17.15 C, 1.44 H, and 81.41 F.
• CHF3

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Finding Empirical Formula

• Find empirical formula of 26.56 K, 35.41 Cr,
  and rest O.
• K2Cr2O7

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Finding Molecular Formula

• x(empirical formula) molecular formula
• x(Emp.Form Mass) Molec.Form Mass
• x Molecular Mass
• Empirical Mass

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Finding Molecular Formula

• Determine molecular formula of compound with
  empirical formula CH and formula mass of 78.110
  amu.

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Finding Molecular Formula

• Sample has formula mass of 34.00 amu has 0.44g H
  and 6.92g O. Find its molecular formula.