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Classifying Chemical Reactions

Classifying Chemical Reactions. Synthesis Reactions. A chemical reaction in which 2 or more reactants combine to form a new product. Represented by general formula: A + B = AB or + = Here, 2 reactants combine to form one product. Example: Haber Process.

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Classifying Chemical Reactions

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  1. Classifying Chemical Reactions

  2. Synthesis Reactions A chemical reaction in which 2 or more reactants combine to form a new product. Represented by general formula: A + B = AB or + = Here, 2 reactants combine to form one product.

  3. Example: Haber Process An important product made by a synthesis reaction is ammonia NH3 It is used as a fertilizer to optimize crop yields, making paper, extracting nickel and zinc, in explosives, and cleaning products. Fritz Haber (German) patented a process for making ammonia: N2(g) + 3H2(g)  2 NH3(g)‏

  4. Synthesizing Binary Ionic Compounds Problem: Complete and balance the synthesis reaction: Na(s) + Cl2(g)  _____________ Step 1: What is the reaction type? Synthesis (form one product)‏ Step 2: Use ion charges to make the most likely product. Na (+1) Cl (-1)‏

  5. Step 3: Figure out the ratio of atoms NaCl (1:1)‏ Step 4: Write the equation, and balance Na(s) + Cl2(g)  NaCl(s)‏ 2Na(s) + Cl2(g)  2NaCl(s)‏

  6. You Try it! http://www.youtube.com/watch?v=oy8dzOB-Ykg You try it! P. 184 #1, 2. P. 185 # 1-4 P. 182 Case Study on Hydrogen Fuel with a partner. Do for homework.

  7. Decomposition Reactions Is a chemical reaction in which a compound breaks down into 2 or more products. General chemical equation: AB = A + B or = + Reactants will always be a compound Like the reverse of a synthesis reaction

  8. Examples Making hydrogen from water The development of hydrogen as a source of fuel, relies on the ability to make it from water in a process called electrolysis. 2H2O (l)  2H2(g) + O2(g)‏ Electrical current is used to break the bonds between hydrogen and oxygen.

  9. Example 2: TNT (explosive)‏ • 2C7N5N3O6(s)  3N2(g) + 5H2O(g) + 7CO(g) + 7C(s)‏ • Rapid expansion of these gases pushes material away from the blast site, producing an explosion

  10. Sample Problem AgCl(s)  _______________ Step 1: What type of reaction? Decomposition (need 2 elements)‏ Step 2: What do each of the elements look like on their own? Remember to write the state! Ag(s) + Cl2(g)‏ Step 3: Write a balanced equation. AgCl(s)  Ag(s) + Cl2(g)‏ 2AgCl(s)  2Ag(s) + Cl2(g)‏

  11. You try it!! P. 187 # 1-3 Activity 5-2 on page 188 (you need a modeling kit)‏ Review Questions: P. 189 # 6-8

  12. Single Displacement Reactions When an element takes the place of another element that is in a compound. Could be a metal replacing a metal or an non-metal replacing a non-metal. General formula: A + BC = AC + B (A is a metal)‏ A + BC = BA + C (A is a non-metal)‏ + --> +

  13. Examples… Cu(s) + 2AgNO3(aq) -> Cu(NO3)2(aq) + Ag(s)‏ This reaction does not go in reverse! Why can Ag not replace Cu? It is because of the reactivity of the metals. We have an activity series to help us predict what will react with what. The Activity Series is a list of elements that is organized according to their chemical reactivity.

  14. Activity Series Lithium Potassium Calcium Sodium Magnesium Aluminum Zinc Iron Nickel Tin Hydrogen Copper Silver Platinum gold Most reactive Least reactive

  15. Hydrogen??? Notice that hydrogen is on the activity series and it is not a metal! Because hydrogen is positively charged as an ion, it can take the place of metals in compounds. The metals above hydrogen in the series can replace hydrogen, but the metals below hydrogen cannot.

  16. Example. Use the activity series to predict if the following single displacement reaction occurs. Al(s) + NiBr3(aq) __________ Step 1: Check Activity Series chart. Al is higher than Ni, Al will replace Ni. Step 2: Form new compound. Watch out for ionic charges and figure out the ratio Al (3+) and Br (1-)‏ Step 3: What does the other element look like on its own? Ni(s) has no charge as a pure element Step 4: Write the balanced equation. Al(s) + NiBr3(aq)  Ni(s) + AlBr3(aq)‏

  17. Non-metals The ion of a non-metal is negatively charged, so it can be replaced with only another non-metal. F2(g) + NaI(s) ______________ Answer: F2(g) + 2NaI(s)  I2(s) + 2NaF(s)‏

  18. You Try It!! P. 193 # 1, 2. P. 195 # 1-4

  19. Double Displacement Is a chemical reaction in which the positive ions of 2 compounds change places and form 2 new compounds. General chemical equation: AB + CD = AD + CB + = +

  20. Example AgNO3(aq) + K2CrO4(aq)  ? Ag2CrO4(s) + 2KNO3(aq)‏ Try it! P. 196 # 1 and 2 P. 198 # 1-7

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