1 / 20

Rules for Balancing Equations

Rules for Balancing Equations. Determine the correct formula for all reactants and products. Write the formulas for the reactants on the left side of arrow and the products on the right.

truda
Download Presentation

Rules for Balancing Equations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Rules for Balancing Equations • Determine the correct formula for all reactants and products. • Write the formulas for the reactants on the left side of arrow and the products on the right

  2. Count the number of atoms on each side of the reaction. If a polyatomic ion appears unchanged on both sides count it as one unit. • Balance the elements one at a time using coefficients. • NEVER CHANGE SUBSCRIPTS TO BALANCE

  3. Combination reactions • Two or more substances come together to form a compound • A + B è AB • Mg + O2è MgO

  4. Combination Reactions 2H2 + O2 => 2H2O

  5. Special combination reactions • A metal oxide and water give a base • A base is a compound with hydroxide • K2O + H2O è KOH • CuO + H2O è ? • Right !! Copper(II) hydroxide

  6. Special combination reactions • A nonmetal oxide and water give an acid • An acid is a compound with hydrogen • SO3 + H2O è H2 SO3 and/orH2 SO4 • NO2 + H2O è ? • Right !! Nitric or nitrous acid

  7. Important fact • Combination reactions are responsible for acid rain. • Sulfuric acid, nitric acid and carbonic acid are involved. • What nonmetal oxides are involved? • Where do they come from?

  8. Decomposition reaction • A substance breaks down forming two or more substances: • ABè A + B • NI3=è N2 + I2 MnO2 • H2O2 è H2O + O2

  9. Single replacement reactions • A + BC è AC + B • Aluminum + Iron(II) oxideè Aluminum oxide + Iron • 2Al(s) Fe2O3(s) + --> Al2O3(s) + 2Fe(s)

  10. For metals, check the reactivity series A more reactive metal will “bump” a less reactive one Zn + HCl è ZnCl2 + H2 Single replacement: will it or will it not happen?

  11. Magnesium is placed in sulfuric acid Mg + H2SO4è MgSO4 + H2 zinc is placed in phosphoric acid 3Zn + 2H3PO4è Zn3(PO4)2 + 3H2 Potassium is placed in contact with aluminum chloride 3K+ AlCl3è3KCl + Al Single replacement: will it or will it not happen?

  12. Single replacement: will it or will it not happen? • For non metals – look to the periodic table (as an activity series) • F is more reactive than Cl • F2 + HCl è HF + Cl2 But – • Cl2 + HF è no reaction

  13. Write single replacement equations • Magnesium is added to lead nitrate • Iron is added to aluminum sulfide • Sodium is added to calcium carbonate

  14. Group VIIA F Cl Br I At Write single replacement equations • Cl2 + NaI => ? • I2 + NaCl => ? • K + NaCl => ?

  15. Double Replacement • Two compounds interact • The cations trade places • AB + CD è AD +CB • Na3PO4 + FeCl3è Fe3PO4 + NaCl

  16. What is the precipitate • Silver nitrate and sodium hydroxide react: • AgNO3 + NaOH è NaNO3 + AgOH

  17. Check the solubility tables AlCl3 + NaOH è Al(OH)3 (s) + NaCl (aq) • How do we know that the aluminum hydroxide is the precipitate? We look at a solubility table • If the solubility table indicates “I” (insoluble), expect the substance to be a precipitate

  18. Combustion reactions • Fuel + oxygen gives carbondioxide, water, and energy • C3H8 (g) + 5O2 (g) -----> 3CO2 (g) + 4H2O (g) • Fuels have carbon, hydrogen, and sometimes oxygen

  19. Organic molecules: The alkanes CnH2n+2 • Methane CH4 • Ethane C2H6 • Propane C3H8 • Butane C4H10 • Pentane (five carbons) C5H12 • Hexane (six carbons) C6H14 • Heptane (seven carbons) C7H16 • Octane (eight carbons) C8H18

  20. Can you write balanced equations for the combustion of these hydrocarbons? • Methane (one carbon) • Ethane (two carbons) • Propane (three carbons) • Butane (four carbons) • Pentane (five carbons) • Hexane (six carbons) • Heptane (seven carbons) • Octane (eight carbons)

More Related