1 / 19

Warm Up:

Learn how to balance chemical equations and calculate empirical formulas with step-by-step instructions. Perfect for chemistry students.

gblount
Download Presentation

Warm Up:

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. Warm Up: • Which of the following represents an empirical formula? • C6H8O6 • C2H4 • C3H4O3 • C7H14

  2. What are the empirical and molecular formulas for a compound with 86.88% carbon and 13.12% hydrogen and a molecular weight of 84 g? • Empirical 86.88 g C / 12g = 7.24 mol / 7.24 = 1 13.12 g H / 1 g= 13.12 mol / 7.24 = 1.8 CH2

  3. Molecular 84/14= 6 C6H12

  4. Balancing Equations

  5. Al + O2 reactants (aka reagents) products yields → Al2O3

  6. The Law of Conservation of Mass • states that the mass of the reactants equal the mass of the products • Atoms cannot be created nor destroyed in a chemical change—therefore, the number of each type of atom on each side of the reaction must be equal • Coefficients are used to balance chemical reactions

  7. Al + O2 → Al2O3 • Is this equation balanced? Left side:             Right side: Al O

  8. ___Al + ___O2 → ___Al2O3 • Balance this equation

  9. Choosing which atom to start with • Start with elements that appear only one time on each side and elements that are in the most complex compounds.  • End with elements that appear more than once on a side or elements that appear uncombined on one side or the other.

  10. Balancing Equations

  11. Inspection Method • Make a list of the elements in the reaction • Count the number of each type of atom on each side of the reaction • Add coefficients to balance the number of atoms • When all elements are balanced, place a “1” in any empty coefficient location

  12. Never touch subscripts when balancing equations since that will change the composition and therefore the substance itself. • Check to be sure that you have included all sources of a particular element that you are balancing on a particular side since there may be two or more compounds that contain the same element on a given side of an equation. • Adjust the coefficient of mono atomic elements near the end of the balancing act since any change in their coefficient will not affect the balance of other elements • When there are a group of atoms that are acting as a unit such as a polyatomic ion and they appear intact on both sides of the equation, it is best to balance them as a self contained group.

  13. Polyatomic Ions • Ions: atom or molecule which has gained or lost electrons giving it a negative or positive charge • Anion = negative ion • Cation = positive ion • Polyatomic: more than 1 atom • Table E

  14. ___NH3+___O2 →___NO+___H2O • Balance this equation 4 NH3+5 O2 →4 NO+6 H2O When you’re done…check to make sure you have the lowest whole number coefficients and the equation cannot be reduced

  15. Combustion Equation • ___CH4 + ___O2 ___CO2 + ___H2OBalance this equation 1 CH4 + 2 O2 1 CO2 + 2 H2O

  16. 1 CH4 + 2 O2 1 CO2 + 2 H2O • If 44 g of methane (CH4) reacted, how many moles of water were produced? 44 g x 1 mol CH4= 2.75 mol CH4 16 g 2.75 mol CH4 x 2 mol H2O = 5.5 1 mol CH4 mol H2O

  17. CaCl2 + AgNO3 AgCl + Ca(NO3)2 • Using the above unbalanced equation, calculate how many grams of AgCl will be produced if 100 g of CaCl2 reacts?

  18. CaCl2 + 2AgNO3 2AgCl + Ca(NO3)2 100 g CaCl2 x 1 mol CaCl2 = 0.90 mol CaCl2 111 g CaCl2 0.90 mol CaCl2 x 2 mol AgCl = 1.8 mol AgCl 1 mol CaCl2 1.8 mol AgCl x 143.5 g AgCl = 258.3 g AgCl 1 mol AgCl

More Related