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Chemical Formulas and Chemical Compounds

Chemical Formulas and Chemical Compounds. Chapter 7. Chemical Formulas. Aluminum Sulfate formula unit Al 2 (SO 4 ) 3 Carbon Tetrachloride molecule CCl 4. Monatomic Ions. Def: ions formed from a single atom Naming ions Cation – use element name Li +1 – Lithium ion Al +3 – Aluminum ion

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Chemical Formulas and Chemical Compounds

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  1. Chemical Formulas and Chemical Compounds Chapter 7

  2. Chemical Formulas • Aluminum Sulfate formula unit • Al2(SO4)3 • Carbon Tetrachloride molecule • CCl4

  3. Monatomic Ions • Def: ions formed from a single atom • Naming ions • Cation – use element name • Li+1 – Lithium ion Al+3 – Aluminum ion • Anion – change ending of element to –ide • N-3 – Nitride ion O-2 – Oxide ion

  4. Monatomic Ions • d – block elements and others with multiple ions • Use Roman numeral in name • Fe+3  Iron(III) ion • Fe+2  Iron(II) ion • Metals always have positive charge

  5. Polyatomic Ions

  6. Polyatomic Ions • NO3- Nitrate • NO2-  Nitrite • The –ate means 1 more oxygen • SO4-2  Sulfate • SO3-2  Sulfite

  7. Polyatomic Ions • ClO4-  Perchlorate • ClO3-  Chlorate • ClO2-  Chlorite • ClO -  Hypochlorite

  8. Binary Ionic Compounds • Def: composed of 2 elements • Total (+) charge must = total (-) charge • Write the formula: • Mg and Cl • Mg+2 Cl-1 • MgCl2 • K and N • Al and O

  9. Compounds with Polyatomic Ions • Iron(II) and Nitrite • Silver and Chromate • Calcium and Hydroxide

  10. Naming Ionic Compounds • Name the cation first, then the anion • NaOH • RbCl • Ag2SO3 • Fe3N2 • CuMnO4

  11. Writing Formulas • Potassium sulfide • Copper(II) sulfate • Sodium carbonate • Calcium chloride • Aluminum hypochlorite

  12. Naming Binary Covalent Compounds • CO, CO2 • We use PREFIXES in the name!! • Only COVALENT compounds use PREFIXES

  13. Prefixes

  14. 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)

  15. Examples • N2O4 • PCl5 • S3Br6 • Nitrogen Dioxide • Boron Trifluoride • Diphosphorus Pentoxide

  16. 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-

  17. Naming Oxyacids • Replace ending of anion name • Anion Suffix Acid Suffix • - ite - ous • - ate - ic

  18. Naming Oxyacids • H2SO4 anion SO4-2  Sulfuric Acid • H2SO3 • HClO4 • HNO3

  19. Naming Oxyacids • Acetic Acid • Dichromic Acid • Nitrous Acid

  20. Naming Binary Acids • Use prefix hydro- • Use suffix –ic • Followed by acid

  21. Naming Binary Acids • HCl • HF • HI • HBr • HCN

  22. 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

  23. Molar Mass • Def: mass of 1 mole of compound – use molar masses of elements (g/mol) • (NH4)2CrO4

  24. Molar Mass in Conversions • Remember flow chart?? • Grams  Moles  Particles • What is mass (g) of 3.04 mol of ammonia vapor, NH3? • How many molecules are in 4.15 x 10-5g C6H12O6?

  25. 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 1023hydrogen ions in your compound?

  26. 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 basket’s mass is from the apples?

  27. 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?

  28. Empirical Formula • Def: formula showing smallest whole-number mole ratio • Ex: B2H6 Molecular Formula BH3 Empirical Formula

  29. Finding Empirical Formula • Determine the empirical formula of the compound with 17.15% C, 1.44% H, and 81.41% F. • CHF3

  30. Finding Empirical Formula • Find empirical formula of 26.56% K, 35.41% Cr, and rest O. • K2Cr2O7

  31. Finding Molecular Formula x(empirical formula) = molecular formula x(Emp.Form Mass) = Molec.Form Mass x = Molecular Mass Empirical Mass

  32. Finding Molecular Formula • Determine molecular formula of compound with empirical formula CH and formula mass of 78.110 amu.

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

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