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A word about ….

Learn about single replacement reactions where metals and nonmetals replace elements in compounds. Use an activity series table to predict reactions. Practice predicting reactions with examples.

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A word about ….

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  1. A word about …. Single Replacement Reactions

  2. Single Replacement Reactions A + BX  AX + B Element + Compound  New Element + New Compound A is replacing B in the compound – A is more active than B

  3. Single Replacement Rxns 2 Li(s) + 2 H2O(l)  2 LiOH(aq) + H2(g) • In this reaction, a metal replaces a hydrogen in a water molecule.

  4. Single Replacement Rxns • Another common type is when one metal replaces another metal in a compound. • Cu(s) + 2 AgNO3(aq)  2 Ag(s) + Cu(NO3)2(aq) • Copper replaced silver in the compound.

  5. Single Replacement Rxns • Finally, one nonmetal can replace another nonmetal in a compound. • F2 + 2NaBr  2NaF + Br2 • Fluorine replaced bromine in the compound.

  6. Single Replacement Reactions • Metals have different reactivities. • You have to predict if a given metal and a given compound will react or not. • You need an activity series, a list of elements organized by how easily they undergo certain chemical reactions.

  7. Single Replacement Rxns • Table J is an activity series. The more reactive a metal, the easier it loses its valence electrons. • The most active metal is at the top. • The least active metal is at the bottom. • Use Table J to determine if a reaction will occur.

  8. Single Replacement Rxns • The rule is: • A metal can replace any metal listed below it that is in a compound. • It cannot replace any metal listed above it. • The higher the metal, the more it wants to lose its electrons!

  9. Ag(s) + Cu(NO3)2(aq)  ? • What is the metal and the metal cation? • Ag and Cu+2 • Locate Ag and Cu in Table J. • Ag is below Cu so this reaction will not go. Ag is less reactive than Cu.

  10. Cu(s) + 2 AgNO3(aq)  ? • What is the metal and the metal cation? • Cu and Ag+1 • Locate Cu and Ag in Table J. • Cu is above Ag in Table J. Cu is more reactive than Ag. This reaction will go. •  2 Ag(s) + 2 Cu(NO3)2(aq)

  11. Single Replacement Reactions • Table J can also be used to predict if • A nonmetal replaces another nonmetal in a compound. • Halogens are often the nonmetal. • Nonmetals are WINNERS! So the nonmetals at the top of Table J want to gain electrons the most. • Most active halogen = fluorine at top. • Least active halogen = iodine at bottom.

  12. Single Replacement Reactions • The rule is: • A more active halogen replaces a less active halogen that is part of a compound in aqueous solution. • F2(g) + 2 NaBr(aq)  2 NaF(aq) + Br2(l) • This reaction occurs because F2 is above Br2.

  13. Single Replacement Reaction NR • Br2(g) + 2 NaF(aq)  ? • Br2 is below F2 in Table J. This reaction does not occur.

  14. Summary • If the “stand-alone” element is higher in Table J than the “like” element in the compound, the reaction will proceed.

  15. Use Table J to predict if these reactions occur. • K(s) + ZnCl2(aq)  • Fe(s) + Na3PO4(aq)  • Cu(s) + Mg(NO3)2(aq)  • Al(s) + SnCl2(aq)  • Ca(s) + KBr(aq)  • Ti(s) + Pb(NO3)2(aq)  • Cl2(g) + HF(aq)  • F2(g) + CaI2(aq)  Yes No No Yes No Yes No Yes

  16. Summary: Predicting Single Replacement Reactions • Identify stand-alone element. • Determine if stand-alone element is a metal or a nonmetal. (For the purposes of Table J, H2 is a metal.) • Compare the stand-alone element to the corresponding element in the compound. • If the stand-alone element is higher in Table J than the corresponding element in the compound, then the reaction occurs.

  17. Next Step • If the reaction proceeds, you have to figure out what the products are (say their names first, then write the formulas) and then balance the equation. • If the reaction does not go, you just write NO REACTION.

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