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Chemical Reactions

Chemical Reactions. with Ionic Equation Writing. 2 Classifications. 1 . Redox Reaction There is a change in oxidation number between reactant side and product side Ca + Fe 3 (PO 4 ) 2 Ca 3 (PO 4 ) 2 + Fe. Oxidation # Ca = 0 Fe 2+ PO 4 3-. Ca 2+ PO 4 3- Fe = 0.

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Chemical Reactions

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  1. Chemical Reactions with Ionic Equation Writing

  2. 2 Classifications • 1. Redox Reaction • There is a change in oxidation number between reactant side and product side • Ca + Fe3(PO4)2 Ca3(PO4)2 + Fe Oxidation # Ca = 0 Fe2+ PO43- Ca2+ PO43- Fe = 0 Diatomics have an oxidation # of zero

  3. 2 Classifications (cont.) • 2. Non-Redox Reaction • No change in oxidation number between reactant side and product side • NaCl + K2SO4 Na2SO4 + KCl Oxidation # Na+ Cl- K+ SO42- Na+ SO42- K+ Cl- Typically 2 ionic compounds reacting together

  4. Non Redox Reactions • If a compound is soluble in water, • it exists as ions in water. • If a compound is insoluble in water, • It exists as a precipitate (solid) in water

  5. We are going to assume all reactant compounds are soluble in water as we practice making ions…..

  6. Non Redox Reactions • If soluble in water: • NH4F will exist as • NH4+ • F- NH4+ F-

  7. Non Redox Reactions • If soluble in water: • H2CO3will exist as • H+ • CO32- H+ CO32- But really 2H+ H+

  8. Non Redox Reactions • If soluble in water: • Al(NO3)3will exist as • Al3+ • NO3- NO3- NO3- Al3+ But really 3NO3- NO3-

  9. Non Redox Reactions • 1. Both reactants are soluble in water • Mark with (aq) • 2. Must determine if products are soluble or insoluble using solubility rules • If soluble – mark with (aq) • If insoluble – mark with (s)

  10. Double Replacement Two elements in reactants take the place of each other AB + CD AD + CB AgNO3(aq)+ NaCl(aq)AgCl(s) + NaNO3(aq) Zn(OH)2(aq) + 2HCl(aq)ZnCl2(aq)+ 2H2O(l)

  11. Double Replacement • Reactants must be two ionic compounds or acids. • Usually in aqueous solution • Na2SO4(aq) + CaCl2(aq)® • The positive ions change place. • Na2SO4(aq)+ CaCl2(aq)®Ca+2SO42- + Na+1Cl-1 • Na2SO4(aq) + CaCl2(aq)® CaSO4(s) + 2NaCl(aq)

  12. To Double Replace or Not to Double Replace? That is the Question! • Will only happen if one of the products: • doesn’t dissolve in water and forms an insoluble solid (s) (precipitate). • is a gas that bubbles out. • is water (H2O) (neutralization reaction).

  13. Predicting the Precipitate • Insoluble salt = a precipitate • Solubility rules (see handout for explanation) CASH N GiAm

  14. Solubility Rules PracticePredict whether each of the following will be soluble (aq) or an insoluble ppt (s): • KCl • Na2SO4 • CaSO4 • AgSO4 • Na2CO3 • MgS

  15. Solubility Rules Practice Answers • KCl(aq) • Na2SO4(aq) • CaSO4(s) • AgSO4(s) • Na2CO3(aq) • MgS(s)

  16. Complete & Net Ionic Equations • Many reactions occur in water- that is, in aqueous solution • Many ionic compounds “dissociate”, or separate, into cations and anions when dissolved in water • Now we can write a complete ionic equation & net ionic equation.

  17. Complete Ionic Equation • Example: AgNO3(aq) + NaCl (aq) AgCl (s) + NaNO3(aq) • this is the full equation (molecular equation) 2. now write it as an complete ionic equation Anything (aq) will dissociate (separate into ions) Ag+ + NO3- + Na+ + Cl-  AgCl(s) + Na+ + NO3-

  18. Net Ionic Equation Complete ionic equation: Ag+ + NO3- + Na+ + Cl-  AgCl(s) + Na+ + NO3- 3. can be simplified by eliminating ions not directly involved in making the reaction happen (spectator ions) = net ionic equation Ag+ + Cl- AgCl(s) Na+ and NO3- are spectator ions and are removed in the net ionic equation.

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