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Unit 6: Balancing Chemical Equations, Chemical Reactions & Stoichiometry

Unit 6: Balancing Chemical Equations, Chemical Reactions & Stoichiometry. The GowerHour. Nomenclature Refresher. II. Binary Ionic Compounds A. Background info 1. Metal / ___________ ( _______ is always written first). 2. One element ________ and the other ________.

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Unit 6: Balancing Chemical Equations, Chemical Reactions & Stoichiometry

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  1. Unit 6: Balancing Chemical Equations, Chemical Reactions & Stoichiometry The GowerHour

  2. Nomenclature Refresher

  3. II. Binary Ionic Compounds A. Background info 1. Metal / ___________ ( _______ is always written first). 2. One element ________ and the other ________. 3. ___________ of e- 4. Charged ions attract one another (opposites attract). 5. The compound is _________ Non-metal Metal loses e- gains e- Transfer neutral

  4. (Metal 1st) (Metal 1st) B. Ex. Sodium & chlorine NaCl (1 Na to every Cl) Na+ Cl Ex. Calcium & bromine CaBr2 (2 Br for every 1 Calcium) Ca2+ Br Ex. Aluminum & sulfur Al2S3 (2 Al for every 3 S) Al3+ S2

  5. C. Shortcut to determining formula (Criss-Cross method): • 1. ________ from charge becomes the subscript. • 2. All ionic compounds are _________ (no + or -). • 3. Subscripts are written in ________ possible ratio. • The number “1” is never written (It is implied). • Examples Number neutral lowest Ex. Al3+ O2- Ex. Li+ O2- Al2O3 Li2O (Aluminum oxide) (Lithium oxide)

  6. D. Nomenclature of binary ionic compounds (bi = 2). • 1. _____ is named first (name of atom). • 2. ____________ is named second, ending changed to ____. • If the metal (cation) can have multiple charges, the charge is written as a roman numeral (IUPAC). • (Fe, Cu, Co, Hg, Mn, Sn, Pb) Metal Non-metal -ide 4. Formula to name: a. Li2O _______________ b. Al2O3 _______________ Lithium oxide Aluminum oxide

  7. (III) Iron ___ oxide Ferric oxide e. Fe2O3 __________________ (______________) f. SnO2 __________________ (_______________) Tin ___ oxide (IV) Stannic oxide • Name to formula: • a. Beryllium fluoride ____________ ___________ • b. Potassium bromide ____________ ___________ BeF2 Be2+ F – K+ Br – KBr

  8. (III) ferric IV. Ternary Compounds: (compounds containing ___ or more elements). 1. Name the _______ 2. Find the appropriate name of the _______. 3. Formula to name: 3 cation anion a. Li2SO4 _______________ b. Fe(NO3)3 _________________________ Lithium sulfate Iron ___ (_____) nitrate

  9. Name to formula: • a. Potassium thiocyanate: __________ _________ • b. Aluminum permanganate: __________ _________ • c. Plumbic acetate: ____________ ___________ • d. Cobalt (III) oxalate: ____________ ___________ • e. Sodium hypochlorite: __________ __________ K+ SCN- KSCN Al3+ MnO4- Al(MnO4)3 Pb+4 C2H3O2- Pb(C2H3O2)4 Co3+ C2O42- Co2(C2O4)3 Na+ ClO- NaClO

  10. V. Nomenclature of Hydrates A. Hydrate: Ionic compound with ______ molecules stuck in the _______ lattice. The water is included in the ______ and formula. 1. ZnSO4 7 H20: __________________________ 2. CaCO3 3 H2O: __________________________ 3. Cu2C2O4 2H2O: _________________________________ 4. Calcium chloride pentahydrate: _____________ 5. Cupric acetate monohydrate: _______________________ water crystal name Zinc sulfate heptahydrate Calcium carbonate trihydrate Copper (I) (cuprous) oxalate dihydrate CaCl2 5H20 Cu(C2H3O2)2 H20

  11. CO VI. Binary Molecular Compounds A. Molecular (________) compounds 1. Non-metal to __________. ______of staircase including hydrogen 2. ________ of electrons. Ex. 3. Non-metals can often combine in several different ways. Ex. covalent non-metal Right Sharing (Both Cl need “1” electron) Cl Cl CO2

  12. Nomenclature of binary molecular compounds: • Greek prefixes are used: • mono = hexa = • di = hepta = • tri = octa = • tetra = nona = • penta = deca = 1 6 2 7 3 8 4 9 5 10 mono 2. The prefix “_______” is omitted for the 1st element. Ex. CO = _________________ Carbon monoxide

  13. For oxides the ending “______” is omitted. • a. N2O = ____________________ • b. N2O3 = ____________________ • c. N2O4 = ____________________ • d. NO = ____________________ • e. NO2 = ____________________ • f. NO5 = ____________________ o or a Dinitrogen monoxide Dinitrogen trioxide Dinitrogen tetroxide Nitrogen monoxide Nitrogen dioxide Nitrogen pentoxide

  14. Metal Non-metal • Compound • IonicCovalent • (Charges Cancel Out) (No Charges) • 1. • 2. 2. • 3. 3. Metal / Non-metal Non-metal only No Prefixes!!! Prefixes = Diiodine tetroxide Li20 = Lithium oxide I2O4

  15. Nomenclature (Acids) • A. Acids: Compounds that contain __________ as the positive ion (H+). • B. Exceptions: _____ (water) & ______ (hydrogen peroxide). • C. Binary Acids: Acids that ___ ____ contain oxygen. • 1. Use prefix “______” • 2. Add stem or full name of ______. • 3. Add suffix “___”. • Add the word ______. • Ex. HBr = _________________________ • HCl = _________________________ • HCN = ________________________ hydrogen H20 H2O2 do not hydro anion ic acid Hydrobromic Acid Hydrochloric Acid Hydrocyanic Acid

  16. Ternary Acids: Contain ____ or more elements, __________ oxygen. • Acids formed with anions that contain ______ become ____ acids. • HNO3 (NO3- = _______) __________ • HClO4(ClO4- = ___________) _____________ • H2SO4(SO42- = ________) ___________ • H3PO4(PO43- = ___________) _______________ 3 including -ate -ic Nitrate Nitric acid Perchlorate Perchloric acid Sulfate Sulfuric acid Phosphate Phosphoric acid

  17. Acids formed with anions that contain ____ become ______ acids. • HNO2 (NO2- = ________) ____________ • HClO2 (ClO2- =_________) _____________ • H2SO3 (SO32- =________) ______________ -ite -ous Nitrite Nitrous acid Chlorite Chlorous acid Sulfite Sulfurous acid • Name to formula: • a. cyanic acid __________________ ________ • b. dichromic acid ______________________ _______ • c. hypochlorous acid _____________________ _______ • d. hydrosulfuric acid _______________ ______ H+ OCN- (Cyanate) HOCN Cr2O72- (Dichromate) H2Cr2O7 H+ ClO- (Hypochlorite) HClO H+ H2S H+ S2- (Sulfide)

  18. Go To Page 58 I. Writing Chemical Equations A. To write a word equation, write the names of the reactants to the _____ of the arrow separated by plus signs; write the names of the __________ to the right of the arrow, also separated by plus signs. B. Reactant + Reactant  Product + Product left products

  19. + + CH4 O2 CO2 H2O Methane + Oxygen  Carbon dioxide + Water

  20. + Fe O2 Fe2O3 iron + oxygen  iron(III) oxide

  21. + H2O2 H2O O2 Hydrogen Peroxide  Water and Oxygen

  22. chemical C. A __________ equation is a representation of a chemical reaction; the formulas of the reactants (on the left) are connected by the yield sign (arrow) with the formulas of the products (on the right). D. A skeleton equation is a chemical equation that does not indicate the relative amounts of the reactants and products. • Here is the equation for rusting: Fe + O2 Fe2O3

  23. catalyst E. A _________ is a substance that speeds up the reaction but is not used up in the reaction. Without Catalyst With Catalyst

  24. F. Problems: 1. Hydrochloric acid and solid sodium hydrogen carbonate are shown before being placed in the beaker to react. The products formed are aqueous sodium chloride, water, and carbon dioxide gas. Write a skeleton equation for this chemical reaction.

  25. NaHCO3(s) + HCl(aq) NaCl(aq) + H2O(l) + CO2(g) Reactants: Solid sodium bicarbonate: NaHCO3(s) Hydrochloric acid: HCl(aq) Products: Sodium chloride: NaCl(aq) Water: H2O(l) Carbon dioxide gas: CO2(g)

  26. S(s) + O2(g) SO2(g) 2. Sulfur burns in oxygen to form sulfur dioxide. Write a skeleton equation for this chemical reaction. Include appropriate symbols. Sulfur: S(__) Oxygen: O2(__) Sulfur dioxide: SO2(__) s g g

  27. coefficients II. Balancing Chemical Equations A. To write a balanced chemical equation, first write the skeleton equation. Then use ____________ to balance the equation so that it obeys the law of conservation of mass. B. This is a balanced equation for making a bicycle. The numbers are called coefficients—small whole numbers that are placed in front of the formulas in an equation in order to balance it.

  28. same conserved C. A chemical reaction is also described by a balanced equation in which each side of the equation has the _______ number of atoms of each element and mass is ___________.

  29. Mass Lavoisier products D. Chemical equations must be balanced due to the Law of Conservation of _____. (_________). Reactants are written on the left of the arrow, ________ are written to the right of the arrow. ________________________ E. Equations are balanced by changing ___________, not by changing __________. For now all equations will be balanced using ______ numbers. F. Certain elements will are found as ________ molecules in nature. In a chemical equation, they will be written in this form. The elements are easily remembered by learning the name of the German guy: Mr. ___________. The seven diatomic molecules are:___, ___, ___, ___, ___, ___, and ___. Reactants Products coefficients subscripts whole diatomic HOFBrINCl O2 F2 Br2 I2 N2 Cl2 H2

  30. reactants products G. Tips for balancing equations: 1. Number of atoms of _________ must equal number of atoms of ________. 2. Coefficients are whole numbers written at the _________ of the substances. 3. All atoms are __________ by the coefficients. 4. Subscripts are ______ changed. 5. Keep polyatomic ions together as a _______ if unchanged from reactants to products. 6. Balance single elements _____. 7. Use the even/odd rule. 8. If an element is in _______ compounds, balance that element last. beginning multiplied never group last multiple

  31. 2 (Odd/Even Rule) 2 3 4 4 3 J. Example: • ___NaClO3 ___NaCl + ___O2 • ___Fe3O4 + ___H2 ___Fe + ___H2O K. Sample Problems: 1. Hydrogen + oxygen  water • Zinc + hydrochloric acid  zinc chloride + hydrogen 3. Copper + silver nitrate  cupric nitrate + silver 4. Ferric hydroxide  iron (III) oxide + water (Fe Single element) 2 H2 + O2 2 H2O Zn + HCl 2 ZnCl2 + H2 Cu + AgNO3 2 Cu(NO3)2 + Ag 2 (Keep NO3 together) 2 Fe(OH)3 Fe2O3 + H2O 3 (O in multiple comp)

  32. 2 C2H6 + O2 7 4 CO2 + H2O 6 Ca + H2O Ca(OH)2 + H2 K + H2SO4 K2SO4 + H2 3 Ca(NO3)2 + Al2(SO3)3 3 CaSO3 + Al(NO3)3 2 P2O5 + H2O H3PO4 3 2 (Odd/Even w/ oxygen) 2 5. Ethane (C2H6) + oxygen  carbon dioxide + water 6. Calcium + water  calcium hydroxide + hydrogen 7. Potassium + sulfuric acid  potassium sulfate + hydrogen 8. Calcium nitrate + aluminum sulfite  calcium sulfite + aluminum nitrate 9. Phosphoric acid is formed when crystalline diphosphorus pentoxide is dissolved in water. 2

  33. Balancing Chemical Equations: Algebraic Technique A. Balance the following equation: Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4 STEP 1: Assign letter to unknown coefficients: a Ca3(PO4)2 + b H2SO4c CaSO4 + d H3PO4 STEP 2: Make a grid indicating the appearance of element or ion in each species of the equation. Use whole number and the coefficient to indicate the appearance. Ca 3a + 0 = c + 0 PO4 2a + 0 = 0 + d H 0 + 2b = 0 + 3d SO4 0 + b = c + 0

  34. STEP 3: Reduce the equations: 3a = c 2a = d 2b = 3d b = c STEP 4: Assume a = 1; solve for coefficients a = 1 b = 3 c = 3 d = 2 STEP 5: Write equation with coefficients: Ca3(PO4)2 + 3 H2SO43 CaSO4 + 2 H3PO4

  35. a b c d e f 4 2 6 6 3 9 Na 2a = 2e a = 1 C a + b = f e = 1 A. Examples: 1. ___Na2CO3 + ___C + ___Sb2S3 ___Sb + ___Na2S + ___CO2 O 3a = 2f a = 6 Sb 2c = d 3c = e S e = 6 f = 9 x 6 c = 2 d = 4 b = 3

  36. a b c d 12 6 15 2 C 6a = c a = 1 a = 2 H 6a = 2d c = 6 O 2b = 2c + d c = 12 x 2 d = 3 2. ___C6H6 + ___O2  ___CO2 + ___H2O d = 6 b = 15 a b c d 12 4 6 1 3. ___HClO4 + ___P4O10  ___H3PO4 + ___Cl2O7 a = 1 H a = 3c a = 12 Cl a = 2d c = 4 O 4a + 10b = 4c + 7d P 4b = c x 12 d = 6 b = 1

  37. a b c d e f g 1 4 4 4 1 8 4 Mn b = 1 a = e b = 4 O 4. ___MnO4 + ___CaC2O4 + ___H2SO4 ___CaSO4 + ___Mn + ___CO2 + ___H2O d = 1 4a + 4b = 2f + g d = 4 Ca b = d c = 1 c = 4 C 2b = f g = 1 g = 4 H 2c = 2g f = 2 x 4 f = 8 SO4 c = d a = 1 e = 1

  38. a b c d 2 8 11 4 Fe a = 2c a = 1 a = 4 S 2a = d O 2b = 3c + 2d c = 2 5. ___FeS2 + ___O2  ___Fe2O3 + ___SO2 x 4 d = 2 d = 8 b = 11 a b c d 14 15 2 6 6. ___C7H6O2 + ___O2  ___CO2 + ___H2O a = 1 C 7a = c a = 2 H c = 7 6a = 2d c = 14 O d = 3 x 2 2a + 2b = 2c + d d = 6 b = 15

  39. Go To Page 67 VI. Reaction Types: A. The five general types of reaction are combination, decomposition, single-replacement, double-replacement, and combustion. B. A combination reaction is a chemical change in which two or more substances react to form a ______ new substance. single

  40. NaCl(s) Combination Remember: HOFBrINCl A + X  AX 2 Na (s) + Cl2(g) 2 C. Synthesis (____________)   General form:  1. element + element  compound  a. sodium + chlorine  b. calcium + oxygen  c. lithium + sulfur  d. aluminum + oxygen  Na+ Cl- 2 2 Ca (s) + O2(g) CaO(s) Ca2+ O2- Li (s) + S(s) Li2S(s) 2 Li+ S2- 4 Al (s) + O2(g) 3 2 Al2O3(s) Al3+ O2-

  41. O2- OH- 2. metal oxide + water metal hydroxide a. Na2O(s) + H2O() b. CaO(s) + H2O() c. Al2O3(s) + H2O() Na+ NaOH(aq) 2 Ca2+ Ca(OH)2(aq) Al3+ 3 Al(OH)3(aq) 2

  42. breaks down D. A decomposition reaction is a chemical change in which a single compound ___________ into two or more simpler products.

  43. 3 2 2 2 2 2 2 Remember: HOFBrINCl AX  A + X element element General fom:  1. Compound  ________ + _______ • FeCl3(s) • CuBr(s) c. MgO(s) Fe(s) + Cl2 (g) Cu(s) + Br2 () Mg(s) + O2 (g)

  44. Metal oxide + water Metal hydroxide OH- O2- Metal oxide water 2. Metal hydroxide  ____________ + _______ • Be(OH)2(s) • Mn(OH)2(s) c. CuOH(s) BeO(s) + H2O () Be2+ MnO(s) + H2O () Mn2+ 2 Cu2O(s) + H2O () Cu+

  45. compound E. A single-replacement reaction is a chemical change in which one element replaces a second element in a __________. 1. Two types: Cation & Anion

  46. 2 2 2 2 2 AX + B  BX + A more 2. Cation replacement - ****MUST use the Activity Series of Metals**** General form: (Single element must be ______ reactive than the element it replaces). • Sn(s) + NaNO3(aq) • Zn(s) + H2SO4(aq) • K(s) + CaCl2(aq) • Na(s) + H2O(l) e. Cu(s) + HCl(aq) Remember: HOFBrINCl NR ZnSO4(aq) + H2 (g) Zn2+ SO42- KCl (aq) + Ca (s) K+ Cl- NaOH (aq) + H2 (g) Na+ H+ OH- NR

  47. (Fig. 4.15) Activity Series of Metals • Li • K • Ba • Ca • Na React with cold water to produce H2 • Mg • Al • Zn • Cr • Fe • Cd React with steam to produce H2 • Co • Ni • Sn • Pb React with acids to produce H2 • H • Cu • Ag • Hg • Pt • Au Do NOT react with water or acids Increasing Reactivity

  48. 2 2 more Remember: HOFBrINCl AX + Y  AY + X 3. Anion replacement - ****MUST use the periodic table**** (Single element must be ______ reactive than the element it replaces. General form: Halogens (Column ___________) Reactivity: ___>____>____>____ a. Cl2(g) + NaBr(aq) b. I2(s) + KBr(aq) c. F2(g) + CaCl2(aq) VIIA or 17 F2 Cl2 Br2 I2 NaCl (aq) + Br2 (g) NR CaF2(aq) + Cl2 (g)

  49. positive ions AX + BY  AY + BX F. A double-replacement reaction is a chemical change involving an exchange of ____________ between two compounds. General form:

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