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Single Displacement Reactions

Single Displacement Reactions. One element in a compound is displaced (or replaced) by another element. A + BC  AC + B. Single Displacement Rxns. Cu (s) + Ag NO 3 ( aq )  Cu (NO 3 ) 2 ( aq ) + Ag (s) Na (s) + ( H + )( OH - )(l)  Na OH ( aq ) + H 2 (g)

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Single Displacement Reactions

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  1. Single Displacement Reactions One element in a compound is displaced (or replaced) by another element. A + BC  AC + B

  2. Single Displacement Rxns Cu(s) + AgNO3(aq) Cu(NO3)2(aq) + Ag(s) Na(s) + (H+)(OH-)(l)  NaOH(aq) + H2(g) For S.D. rxns with water, think of HOH as H+OH-, un even though that is not the case.

  3. Check this: Thermite Reaction Al(s) + Fe2O3(s)  Al2O3(s) + Fe(s) Highly exothermic rxn; molten iron produced http://www.youtube.com/watch?v=dypZ7eh0wLQ Thermite(Aluminothermic) welding method for rail joints by Rajeev Shrivastava (Indian Railway)

  4. Also . . . Al(s) + CuO Al2O3(s) + Cu(s) Al(s) + CuO Al2O3(s) + Cu(s)

  5. and . . . Al(s) + V2O5(s)  Al2O3 + V(s)

  6. Predict the Products Ag(s) + CuSO4(aq)  NR Zn(s) + HOH(l)  NR Some S.D. rxns “work”; others don’t. How can we predict?

  7. Activity Series of Metals Li most reactive metal (least stable) K Ba Ca Na Mg Al Zn Fe Ni Sn Pb HYDROGEN Cu Hg Ag Au least reactive metal (most stable)

  8. Refer to the activity series on data sheet. cf. activity series on p 164 of

  9. Use the activity series to predict the products (if any) of the following . . . Zn(s) + Fe(NO3)3(aq)  Zn(NO3)2(aq) + Fe(s) Ag(s) + HCl(aq)  NR Al(s) + H2SO4(aq)  Al2(SO4)3(aq) + H2(g) Li(s) + HOH(l)  LiOH(aq) + H2(g)

  10. Balance the following equation for the s.d. rxn: Al(s) + H2SO4(aq)  Al2(SO4)3(aq) + H2(g) 2Al(s) + 3H2SO4(aq)  Al2(SO4)3(aq) + 3H2(g) This is called the complete ionic equation. The net ionic equation is: 2Al(s) + 6H+(aq)  2Al3+(aq) + 3H2(g) [SO42- is a spectator ion. It does not react.]

  11. Activity Series for Halogens A molecular halogen (X2) can displace a halide ion (X-) from a compound. F2most reactive Cl2 Br2 I2least reactive

  12. egs. of s.d. rxns with halogens F2(aq) + NaCl(aq)  NaF(aq) + Cl2(aq) I2(aq) + NaBr(aq)  NR

  13. Three Types of Double Displacement Reactions • d.d. reactions that form a precipitate (ppt) • d.d. reactions that produce a gas • The formation of water in an acid-base neutralization reaction

  14. NOW HEAR THIS . . . The activity Series DOES NOT apply to Double displacement reactions. DO NOT USE THE ACTIVITY SERIES FOR DOUBLE DISPLACEMENT REACTIONS . . . EVER . . . NOT EVEN ONCE . . . DON’T EVEN THINK ABOUT IT

  15. d.d. rxns that form a precipitate (ppt) Recall our test for chloride, Cl-, ions: NaCl(aq) + AgNO3(aq)  AgCl(s) + NaNO3(aq) ppt.

  16. Think of d.d. rxns as a type of square dancing: +  switch partners (iecations) AB + CD  AD + CB

  17. Predict the products MgCl2(aq) + KOH(aq)  Mg(OH)2 + KCl Start by “deconstructing” the reactants: Mg2+Cl-K+OH-  Now switch partners—remember to write formulae of neutral compounds Mg(OH)2 + KCl But which one—if any—is the ppt?

  18. Prediction of the ppt in d.d. rxn. Products are: Mg(OH)2 + KCl Refer to solubility chart on data sheet or p 174 of i = insoluble; s = soluble—what do we write? (s)(aq) [for slightly soluble, assume ppt formation]

  19. overall . . . MgCl2(aq) + 2KOH(aq)  Mg(OH)2(s) + 2KCl(aq) [We balance the equation as a final step.] Magnesium hydroxide is the precipitate. K+(aq) and Cl-(aq) are spectator ions.

  20. MgCl2(aq) + 2KOH(aq)  Mg(OH)2(s) + 2KCl(aq) Is the complete (ionic) equation. The net ionic equation is: Mg2+(aq) + 2OH-(aq)  Mg(OH)2(s) Spectator ions are omitted.

  21. Predict pdts of these d.d rxns:(do not balance the eqn’s) Ca(C2H3O2)2(aq) + Na2SO4(aq)  CaSO4(s) + NaC2H3O2 (aq) BaCl2(aq) + (NH4)3PO4(aq)  Ba3(PO4)2(s) + NH4Cl(aq) balanced net ionic equation is: 3 Ba2+(aq) + 2 PO43-(aq)  Ba3(PO4)2(s)

  22. Which ions always form soluble compounds? Look at solubility chart on p 174. sol cations: Na+, K+, NH4+ sol anions: NO3-, ClO3-, ClO4-

  23. 2. d.d. Rxns that Produce a Gas When the following three compounds are formed in a d.d. rxn, they decompose as shown: H2CO3(aq)  HOH(l) + CO2(g) H2SO3(aq)  HOH(l) + SO2(g) NH4OH(aq)  HOH(l) + NH3(aq) eg. NH4Cl(aq) + NaOH(aq)  NH4OH(aq) + NaCl(aq) Actual products NH3(aq) + HOH(l) + NaCl(aq)

  24. Try this one: NaHCO3(aq) + HC2H3O2(aq)  Baking soda acetic acid (vinegar) NaC2H3O2(aq) + H2CO3(aq) Products  NaC2H3O2(aq) + HOH(l) + CO2(g) Overall: NaHCO3(aq) + HC2H3O2(aq)  NaC2H3O2(aq) + HOH(l) + CO2(g)

  25. 3. The Formation of Water in an Acid-Base Neutralization Rxn HCl(aq) + NaOH(aq) NaCl(aq) + HOH(l) acid + base  a salt + water H2SO4(aq) + KOH(aq)  K2SO4(aq) + HOH(l)

  26. Predict the products for these acid-base neutralization rxns HClO4(aq) + NaOH(aq)  NaClO4(aq) + HOH(l) H3PO4(aq) + Ca(OH)2(aq)  Ca3(PO4)2(s) + HOH(l) now balance this equation 2H3PO4(aq) + 3Ca(OH)2(aq)  Ca3(PO4)2(s) + 6HOH(l)

  27. Practice: Write the products and classify each of these reactions Al(s) + HCl(aq)  AlCl3(aq) + H2(g) single displacement C10H20 + O2 C + CO + CO2 + HOH incomplete combustion

  28. and more practice . . . H2 + I2 2HI synthesis COCl2 CO + Cl2 decomposition

  29. and these . . . AgNO3(aq) + K2CrO4(aq)  Ag2CrO4(s) + KNO3(aq) double displ. C3H8 + O2 CO2 + HOH complete combust. Na2SO3(aq) + HCl(aq)  NaCl(aq) + H2SO3(aq) NaCl(aq) + HOH(l)+ SO2(g) double displacement; decomposition

  30. Try this one: CaC2(s) + HOH(l) C2H2(g) + Ca(OH)2(aq) acetylene (Hint: C22- = carbide ion)

  31. Homework Do questions from sections 4.1 and 4.2. Chapter Review Qs also.

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