1 / 68

Thursday Day 1:

Thursday Day 1:. Chemical Reactions Overview Practice formula writing Word and Chemical Equations!. Unit 8: Chapter 8! Chemical Equations and Reactions. p. 258 - 291. Chemical Formula.

kacia
Download Presentation

Thursday Day 1:

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. Thursday Day 1: • Chemical Reactions Overview • Practice formula writing • Word and Chemical Equations!

  2. Unit 8: Chapter 8!Chemical Equations and Reactions p. 258 - 291

  3. Chemical Formula • a notation that uses chemical symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in a substance • Example: CaSO4

  4. Chemical Reaction • The process by which one or more substances change to produce one or more different substances. • Atoms rearrange to form new substances. 2 Parts: • Reactants (the original substances) • Products (the substances that form)

  5. Evidence of a Chemical Reaction There are four signs of a chemical change (chemical reaction), what are they?? • Evolution of a gas (odor) • Formation of a precipitate (solid) • Release or absorption of energy/heat/light • Color change • More specific versions of these changes are listed in the book on pg. 261

  6. Evidences are not enough!! • To prove that a chemical change has occurred, a chemical analysis must be performed to prove that a new substance has formed • Properties of the new substance (density, melting point, boiling point) must be different from those of the original substance

  7. Word Equation • Describes a chemical reaction using words • Done before writing a chemical equation Example: • Methane + Oxygen  Carbon Dioxide + Water

  8. Formula Equation • A representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products • Example: • CH4 + O2 CO2 + H2O

  9. Sometimes heat or energy is needed or formed in a reaction. • If so, they are included in the word equation just like any other reactant or product.

  10. Chemical Equations often include states of matter of the reactants and products: • Abbreviations: • Solid (s) • Liquid (l) • Gas (g) • Aqueous (aq)—this means that the substance is in solution (is dissolved in water)

  11. Example 1: • Methane gas burns in gaseous oxygen, releasing energy, to form carbon dioxide gas and water vapor • Word Equation: • Methane + Oxygen  Carbon Dioxide + Water + Energy • Formula Equation: • CH4(g) + O2(g)  CO2(g) + H2O(g) + Energy

  12. Example 2: • Magnesium metal burns in oxygen gas with a bright white light to make a white powder called magnesium oxide. • Word Equation: • Magnesium + Oxygen  Magnesium Oxide + Energy • Formula Equation: • Mg(s) + O2(g)  MgO(s) + Energy

  13. Monday Day 2: • Check and go over word/chemical eqns • Start Balancing Chemical Equations • Balancing Activity

  14. Tuesday Day 3: • Start Balancing Chemical Equations • Balancing Activity • Balance equations!

  15. Law of Conservation of Mass • All chemical reactions must obey the law of conservation of mass • Atoms get rearranged, but are not created or destroyed • For this reason, all chemical equations must be balanced • The number of atoms of each element must be identical on the reactant side and the product side of a balanced chemical equation.

  16. Balancing Equations • To balance an equation, you must make the number of atoms of each element the same on the reactants side and on the products side • You CANNOT change the formulas of the substances • Do not change subscripts, or you will change the entire compound • You CAN change the coefficients in front of the formulas • A coefficient is small whole number that appears as a factor in front of a formula in a chemical equation

  17. Balancing Equations Activity • Please work on the Balancing Equations Activity using the materials provided – draw with colored pencils

  18. Example 1 & 2: • ___H2 + ___O2 ___H2O • ___HCl + ___K2CO3 ___KCl + ___H2O + ___CO2 2 2 2 2

  19. Example 3: • __(NH4)3PO4+__Pb(NO3)4__Pb3(PO4)4+__NH4NO3 • Hint: Polyatomic ions, when they stay intact, can be balanced as a unit 3 4 12

  20. Example 4: • __Na3PO4 + __Ca(NO3)2 __NaNO3 + __Ca3(PO4)2 2 3 6

  21. Odd-Even Technique • This can be used when you have an odd number of an element on one side, and an even number of that element on the other side • Typically done with diatomic elements, especially oxygen • Steps: • Balance everything except for the particular element • Double all other coefficients • Then determine the coefficient of the diatomic element

  22. Example 5: 2 9 6 6 • ___C3H6 + ___O2 ___CO2 + ___H2O

  23. Balancing Equations Practice • Practice balancing chemical equations on p.9-10

  24. Wednesday Day 4: • Check and go over balancing equations • Start Classifying Chemical Reactions

  25. Day 5: • Classifying Chemical Reactions (con’t)

  26. Why classify rxns? 5 types of reactions • Synthesis • Decomposition • Single Displacement • Double Displacement • Combustion • More easily predict the products that form • Different types of reactions follow certain patterns, making balancing easier

  27. Synthesis ReactionA + B  AB • A reaction in which two or more substances combine to form a new compound • Example: • N2 + 3H2  2NH3 Defining Features: • 2 elements or compounds combine into 1 product ONLY ONE PRODUCT

  28. Synthesis Reaction • Sometimes, more than one product can result • Predict the Products of the following: • Fe + S  • If Fe is +2 • If Fe is +3 • Answer: • FeS • Fe2S3

  29. Decomposition ReactionAB  A + B • A reaction in which a single compound breaks down to form two or more simpler substances • Example: • HgO  Hg + O2 Defining Features: • Compound breaks down into 2 or more parts ONLY ONE REACTANT

  30. Decomposition Reaction • Predict the Products of the following: • 2NI3(s)  • Answer: • N2(g) + 3I2(g)

  31. Single Displacement ReactionA + BX  AX + B • A reaction in which one element replaces another element in a compound • The single displacement reaction will only occur if A is more reactive than B • See the Activity Series • A cation can only replace a cation& an anion can only replace an anion (write charges above elements in eqns)

  32. Activity Series(p12 in P of F) • A series of elements that have similar properties and that are arranged in descending order of chemical reactivity • An element can only displace an element that is below it on the activity series • It is possible for no reaction to occur

  33. Single Displacement Reaction • Examples: • Br2 + 2NaI  2NaBr + I2 • Br2 + 2NaCl  No Rxn Defining Feature: More active element replaces the less active one SINGLE ELEMENT ON EACH SIDE OF REACTION

  34. Single Displacement Reaction • Predict the Products of the following: • Zn + Cu(NO3)2 • Cu + Zn(NO3)2  • Answers: • Cu + Zn(NO3)2 • No reaction

  35. Single Displacement Reaction • Predict the Products of the following: • Br2 + 2 NaI • Br2 + 2 NaCl  • Answers: • 2 NaBr + I2 • No reaction

  36. Double Displacement ReactionAX + BY  AY + BX • A reaction in which a gas, a solid precipitate, or a molecular compound forms from the apparent exchange of atoms or ions between two compounds • Example: • HCl+ NaOHHOH + NaCl Defining Features: the ions switch ‘partners’ TWO COMPOUNDS ON EACH SIDE OF THE REACTION

  37. Double Displacement Reaction • Predict the Products of the following: (remember: write charges) • Na2S + Cd(NO3)2 • Answer: • 2NaNO3 + CdS

  38. Double Displacement Reaction • Predict the Products of the following: • 2RbNO3 + BeF2 • Answer: • 2RbF + Be(NO3)2

  39. Combustion ReactionHydrocarbon + O2(g)  CO2(g) + H2O(g) • The oxidation reaction of a compound, in which heat is released • Often used to generate energy • Example: • 2Mg + O2 2MgO • Most combustion reactions involve hydrocarbons or other carbon-based compounds • Example: • C3H8+ 5O2 3CO2+ 4H2O

  40. Combustion Defining Features: Compound burning with oxygen (O2 as a reactant) to produce oxides usually water and carbon dioxide OXYGEN (O2) = REACTANT or OXIDES FORM (WATER AND CARBON DIOXIDE)

  41. Combustion Reaction • Predict the Products of the following: • C6H12 + O2 • Answer: • CO2 + H2O

  42. Classifying Reactions Examples: • 2NaBr + Ca(OH)2 CaBr2 + 2NaOH • Double Displacement • 2NH3 + H2SO4 (NH4)2SO4 • Synthesis • 4C5H9O + 27O2 20CO2 + 18H2O • Combustion • 3Pb + 2H3PO4 3H2 + Pb3(PO4)2 • Single Displacement

  43. Classifying Reactions Practice • Practice classifying reactions on p. 9-10

  44. Thursday Day 6: • Go over Types of Rxns p.9-10 • Demos

  45. Friday Day 7: • Classifying & Predicting reactions

  46. Classifying Reactions and Predicting Products • 2HgO  • Answer • Decomposition • 2Hg + O2

  47. Classifying Reactions and Predicting Products • Br2 + 2 NaCl • Answer • Single Displacement • NO REACTION

  48. Classifying Reactions and Predicting Products • Zn + H2SO4 • Answer: • Single Displacement • H2 + ZnSO4

  49. Classifying Reactions and Predicting Products • Pb(ClO3)2 + 2KI  • Answer: • Double Displacement • PbI2 + 2KClO3

  50. Classifying Reactions and Predicting Products • 2NH4Cl + Pb(NO3)2 • Answer: • Double Displacement • 2NH4NO3 + PbCl2

More Related