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C 6 H 12 O 6 NaCl H 2 O CO 2 MgBr 2 AgI. UNIT 6: Chemical Formulas, Equations, and Reactions (Chapters 7 & 8). ALL ABOUT NAMING …. Writing a Formula. 1 st : is it IONIC or COVALENT? 2 nd : follow specific rules for that type of compound. Writing IONIC Formulas & Names.
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C6H12O6 NaCl H2O CO2MgBr2 AgI UNIT 6: Chemical Formulas, Equations, and Reactions(Chapters 7 & 8)
Writing a Formula • 1st: is it IONIC or COVALENT? • 2nd: follow specific rules for that type of compound
Writing IONIC Formulas & Names • Cation (metal) + anion (nonmetal) with –ide ending (or polyatomic) ignore subscripts! • Is it in groups 1, 2, or 13? if so, just metal + nonmetal with –ide (or polyatomic) • Is it a transition metal?If so, use roman numerals to show the CHARGE on the cation (metal) when writing the name. • Just like in math class, reduce to lowest common subscripts!
WHAT?! Use the “cross-down” of charges to write formulas! • lithium bromide • aluminum sulfide • iron(III) oxide • copper(II) phosphide • manganese(II) oxide • LiBr • Al2S3 • Fe2O3 • Cu3P2 • MnONOT Mn2O2
When to use a Roman Numeral (transition metals, Sn, Pb) exceptions to Roman Numeral use: Zn+2 and Ag+1
Now YOU try … • magnesium fluoride • calcium sulfide • iron(II) nitride • tin(IV) oxide • aluminum phosphide MgF2 CaS Fe3N2 SnO2 AlP
Going the other way … • CuCl2 • NaF • MgCl2 • KI • TiO2 copper(II) chloride sodium fluoride magnesium chloride potassium iodide titanium (IV) oxide
What are POLYATOMIC ions? • ions with multiple atoms • most are polyatomic ANIONS • one common polyatomic cation: NH4+ (ammonium) • use these JUST like a monatomic (single element) in naming • treat the polyatomic ion like a single anion (put it in parentheses)!
Polyatomic Ion Examples • iron(II) carbonate • strontium nitrate • potassium chlorite FeCO3 Sr(NO3)2 KClO2
Now YOU try … • copper(II) acetate • gallium(III) sulfite • magnesium hydroxide Cu(C2H3O2)2 Ga2(SO3)3 Mg(OH)2
Writing a COVALENT Formula less Eneg element first + more Eneg element with –ide ending use PREFIXES to show number of atoms of each element Name of first element in the formula, use prefixes di- and so forth if necessary Name of second element in formula, use prefixes mono- and so forth if needed
Greek Prefixes • mono- 1 • di- 2 • tri- 3 • tetra- 4 • penta- 5 • hexa- 6 • hepta- 7 • octa- 8 • nona- 9 • deca- 10
Examples • NO • NO2 • N2O • CO • SF2 • SCl2 • PBr3 • BF3 nitrogen monoxide nitrogen dioxide dinitrogen oxide carbon monoxide sulfur difluoride sulfur dichloride phosphorus tribromide boron trifluoride
Now YOU try … • XeCl8 • CCl4 • SF6 • As3I9 xenon octachloride carbon tetrachloride sulfur hexafluoride triarsenic nonaiodide
Going the other way … • boron trifluoride • neon hexafluoride • dinitrogen pentoxide • silicon tetrafluoride BF3 NeF6 N2O5 SiF4
Mix it up .. ionic AND covalent 1. BaI2 2. P4S3 3. I2O5 4. FeS 5. Cs2CO3 6. SnCl2 7. CS2 8. dinitrogen monoxide 9. copper(II) nitrate 10. potassium sulfide 11. sulfur trioxide 12. aluminum carbonate 13. iodine monchloride 14. iron(III) sulfite
Mix it up .. ionic AND covalent 1. BaI2 2. P4S3 3. I2O5 4. FeS 5. Cs2CO3 6. SnCl2 7. CS2 barium iodide tetraphosphorus trisulfide diiodine pentoxide iron(II) sulfide cesium carbonate tin(II) chloride carbon disulfide
Mix it up .. ionic AND covalent 8. dinitrogen monoxide 9. copper(II) nitrate 10. potassium sulfide 11. sulfur trioxide 12. aluminum carbonate 13. iodine monchloride 14. iron(III) sulfite N2O Cu(NO3)2 K2S SO3 Al2(CO3)3 ICl Fe2(SO3)3
Signs of a Chemical Rxn • evolution of heat & light • formation of a gas • formation of a precipitate (solid) • color change • Formation of odor
Law of Conservation of Mass • mass is neither created nor destroyed in a chemical rxn • total mass stays the same • atoms can only REARRANGE 4 H 2 O 4 H 2 O 36 g 4 g 32 g
Chemical Eqns A+B C+D REACTANTS PRODUCTS
Chemical Equations , yields , reacts with
Writing Eqns 2H2(g) + O2(g) 2H2O(g) 1. Identify the substances involved 2. Use symbols to show: • How many? - coefficient • Of what? - chemical formula • In what state? - physical state 3. Remember the DIATOMIC elements: • N2, O2, F2, Cl2, Br2, I2, H2
Writing Eqns • Two atoms of aluminum react with three units of aqueous copper (II) chloride to produce three atoms of copper and two units of aqueous aluminum chloride. • How many? • Of what? • In what state? (aq) (s) Cu (s) AlCl3 Al 2 + 2 3 + 3 CuCl2 (aq)
Describing Eqns • describing coefficients • individual element = “atom” • covalent substance = “molecule” • ionic substance = “unit” 3CO2 2Mg 4MgO 3 molecules of carbon dioxide 2 atoms of magnesium 4 units of magnesium oxide
Describing Eqns to produce Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g) • How many? • Of what? • In what state? One atom of solid zinc reacts with two molecules of aqueous hydrochloric acid one unit of aqueous zinc chloride molecule of hydrogen gas. and one
Balancing Steps • Write unbalanced eqn. • Write each individual element or polyatomic under the arrow in a single column. • Count atoms on each side. • Add coefficients to make #s equal. coefficient subscript = # of atoms • If necessary, reduce coefficients to lowest possible ratio. • Double check!!!
Helpful Tips • Balance one element at a time • Update ALL atom counts after adding a coefficient • If an element appears more than once per side, balance it last • Balance polyatomic ions as single units • “1 SO4” instead of “1 S” and “4 O”
Balancing Example Al + CuCl2 Cu + AlCl3 Al Cu Cl Aluminum and copper(II) chloride react to form copper and aluminum chloride. 2 3 3 2 1 1 1 1 2 3 2 2 6 3 6 3
Balancing Example Sodium sulfite and hydrogen phosphate react to form hydrogen sulfite and sodium phosphate.
Balancing Example Propane (C3H8) reacts with oxygen to produce carbon dioxide and water.
1. Combustion • the burning of any substance in O2 to produce heat A + O2 B CH4(g) + 2O2(g) CO2(g) + 2H2O(g)
Combustion • products: • contain oxygen • hydrocarbons (anything with H and C) will ALWAYS form CO2 + H2O Na(s)+ O2(g) 4 2 Na2O(s) C3H8(g)+ O2(g) CO2(g)+ H2O(g) 5 3 4
2. Synthesis/Composition • the combination of 2 or more substances to form a compound • only ONE product A + B AB
2. Synthesis/Composition H2(g) + Cl2(g) 2 HCl(g)
2. Synthesis/Composition • products: • ionic – “cross down” charges of reactants • covalent – hard to tell Al(s)+ Cl2(g) 2 3 2 AlCl3(s)
3. Decomposition • a compound breaks down into 2 or more simpler substances • only one reactant AB A + B
3. Decomposition 2 H2O(l) 2 H2(g) + O2(g)
3. Decomposition • products: • binary – break into elements • others – hard to tell KBr(l) 2 2 K(s) + Br2(l)
4. Single Replacement • one element replaces another in a compound • metal replaces metal (+) • nonmetal replaces nonmetal (-) A + BC B + AC
4. Single Replacement (SR) Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)
4. Single Replacement • products: • metal metal (+) • nonmetal nonmetal (-) Fe(s)+ CuSO4(aq) Cu(s)+ FeSO4(aq)
5. Double Replacement • ions in two compounds “change partners” • cation of one compound combines with anion of the other- “outsides” and “insides” AB + CD AD + CB
5. Double Replacement (DR) Pb(NO3)2(aq) + K2CrO4(aq) PbCrO4(s) + 2KNO3(aq)
5. Double Replacement • products: • switch negative ions • one product must be insoluble(check solubility table) Pb(NO3)2(aq)+ KI(aq) 2 2 PbI2(s)+ KNO3(aq) NaNO3(aq)+ KI(aq) N.R.
Solubility Chart BaSO4 Mg(OH)2 AgCl, PbCl2Hg2Cl2 PbSO4