Classifying Chemical Reactions

Classifying Chemical Reactions

In Chapter 8, Section 3, the process of classifying chemical reactions is introduced. Understanding the reasons for classification can help in predicting the products that will form. Recognizing patterns among reactions can

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PowerPoint presentation about 'Classifying Chemical Reactions'. This presentation describes the topic on In Chapter 8, Section 3, the process of classifying chemical reactions is introduced. Understanding the reasons for classification can help in predicting the products that will form. Recognizing patterns among reactions can. The key topics included in this slideshow are . Download this presentation absolutely free.

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Slide1Notes: Ch 8-Section 3“ Classifying Chemical Reactions”

Slide2Classifying reactionsreasons for classification: • helps to  predict  what  products will form • recognizing  patterns  can  help when  balancing  equations 5  different types of reactions are introduced in chapter 8 • additional  types exist • note--- some  reactions can be  classified as more than 1  type • note--- some  reactions  do not “fit”  any type

Slide3Reaction Types: Combustion Reactions• (def)-  the  oxidation  reaction of an organic compound  in which  heat is released • often used to generate energy ; occurs when a substance  combines with  oxygen   releasing  a large amount of  energy  in the form of heat  and  light

Slide4Many Combustible Compounds areH ydrocarbons • hydrocarbon (def)- a compound  composed of only  carbon  and hydrogen • the combustion of  gasoline produces   energy  used for transportation • example: burning of  propane   C 3 H 8  + 5O 2     3CO 2  + 4H 2 O

Slide5Combustion Reaction---General Pattern:hydrocarbon   +   oxygen     carbon   dioxide   +   water Figure 9 p. 276 The complete combustion of any hydrocarbon, such as methane, yields only carbon dioxide and water

Slide6Combustion Reactions (cont.)• some  combustible compounds are not hydrocarbons • alcohols (compounds made of  carbon , hydrogen  and oxygen ) will also combust • example: combustion of  ethanol   CH 3 CH 2 OH  + 3O 2     2CO 2  + 3H 2 O

Slide7Combustion Reactions (cont.)• if  enough   oxygen  is not available , combustion reactions will be  incomplete and  carbon monoxide and  unburned carbon (soot) will be produced along with the carbon dioxide and water

Slide8Reaction Types: Synthesis Reactions• (def)-  a reaction in which  2 or more substances  combine  to  form a new compound • “ synthesis”  (from Greek) means “ to put together ” • general pattern:   A + X    AX A, X can be  elements  or  compounds AX is a  compound

Slide9Synthesis Reactions (cont.)• two  elements will form a  binary compound • examples: Na + Cl     NaCl   (binary  ionic  compound) C + O 2      CO 2   (binary  molecular  compound) Figure 10 p. 277 When the elements magnesium and oxygen react, they combine to form the binary compound magnesium oxide

Slide10Synthesis reactions (cont.)• compounds  can form a  ternary compound  ( a compound composed of 2 or more elements)   CaO (s) +  H 2 O (l )    Ca(OH) 2 (s) • some  oxides  of non-metals can  combine  with water  to produce  acids CO 2 (g) + H 2 O(l)     H 2 CO 3 ( aq )    (carbonic acid)

Slide11Reaction Types: Decomposition Reactions• (def)-  a reaction in which a  single compound   breaks down  to form two or more simpler substances • general pattern: AX    A + X AX is a  compound A, X can be  elements  or  compounds • are the  opposite  of  synthesis  reactions • often  need heat  or  electricity  to proceed

Slide12Decomposition Reactions (cont.)• binary  compounds usually  decompose   back  into the  2 elements  that compose them • example: decomposition of water   2H 2 O (l)  electricity   2H 2 (g) +  O 2 (g) Figure 11 p. 278 Nitrogen triiodide is a binary compound that decomposes into the elements nitrogen and iodine.

Slide13Decomposition Reactions (cont.)• compounds made up of  3 or more elements  usually  do not decompose back into those elements • example: decomposition of limestone ( CaCO 3 ) CaCO 3 (s)  heat    CaO (s) +  CO 2 (g) • many  synthesis reactions  can be reversed  to become  decomposition reactions

Slide14Reaction Types: Displacement Reactions(Single Replacement Reactions) • (def)-  a reaction that occurs when  1 element replaces  a  similar   element  in a compound • general pattern: A + BX    AX + B  (or) Y + BX    BY + X A, B, Y and X are  elements AX, BX and BY are  compounds • commonly take place in  aqueous  solutions • usually  require  a  smaller amount  of  energy  than synthesis or decomposition reactions

Slide15Reactivity is Ranked byActivity Series • activity series (def)-  a  series of elements  that have  similar properties  and that are  arranged in  descending order  of chemical reactivity

Slide16Activity Series (cont.)• elements are arranged in order, with the most active ones on top  (see Table 4 p. 281 and Appendix A p. 832) • in general, any element listed  can displace those below it , but not above it • allows predictions about displacement reactions to be made

Slide17Figure 12 page 280Copper is the more active metal and displaces silver from the silver nitrate solution. So copper is higher on the activity series than silver is. The Cu 2+  formed gives the solution a blue color

Slide18Reaction Types: Double-DisplacementReactions ( Double Replacement Reactions ) • (def)-  a reaction that occurs when the ions  of 2 compounds  exchange places  in an  aqueous  solution   to  form 2 new compounds • general pattern: AX + BY    AY + BX A, X, B and Y as  reactants  are  ions AY and BX as  products  are  compounds

Slide19Double-Displacement Reactions (cont.) • takes place in  aqueous solution • one of the compounds  produced  is usually a  precipitate , an  insoluble gas or a  molecular compound • the  other  compound is often  soluble  and remains in solution

Slide20Figure 13 page 283• example: the formation of solid lead(II) iodide from an  aqueous solution  of potassium iodide and lead(II) nitrate • equation: 2KI (aq) +  Pb(NO 3 ) 2 (aq)     PbI 2 (s) +  2KNO 3 (aq)

Slide21Figure 13 page 283