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With a partner Name the following: 1. Aluminum Bromide 2. NiS Iron(III ) Oxide CaCl 2 SF 2

With a partner Name the following: 1. Aluminum Bromide 2. NiS Iron(III ) Oxide CaCl 2 SF 2 AgBr 3 Nickel (II) Sulfide Fe 2 O 3 Calcium chloride Sulfur difluoride. 4.2 MOLECULAR AND IONIC EQUATIONS

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With a partner Name the following: 1. Aluminum Bromide 2. NiS Iron(III ) Oxide CaCl 2 SF 2

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  1. With a partner Name the following: 1. Aluminum Bromide 2. NiS • Iron(III) Oxide • CaCl2 • SF2 • AgBr3 • Nickel (II) Sulfide • Fe2O3 • Calcium chloride • Sulfur difluoride

  2. 4.2 MOLECULAR AND IONIC EQUATIONS • Molecular equation, a complete ionic equation, or a net ionic equation: reaction involving ions (use one of the equations depending on the info we want to convey)

  3. ACTIVITY: Group learning Molecular Equations Complete Ionic Equations Net Ionic Equations • I’ll break you up into groups. • Each group will have to take good notes on the equation they are assigned. • I will place you into different groups and each member has to teach the other group members their equation. • The group members take notes of the other equations. • DO NOT JUST COPY DOWN THE NOTES, THE MEMBER MUST EXPLAIN THE EQUATION AND THEN THE OTHER MEMBERS CAN CHECK THEIR NOTES FOR SPELLING. • YOU WILL USE A WHITE BOARD TO TEACH THE MEMBERS.

  4. MOLECULAR EQUATION - Reactants and products are written as if they were molecular substances even though they may actually exist in solution as ions. COMPLETE IONIC EQUATION - Strong electrolytes are written as separate ions in the solution. NET IONIC EQUATION • Ionic equation from which spectator ions have been canceled. • Spectator ion is an ion in an ionic equation that does not take part in the reaction.

  5. BOARD

  6. TYPES OF CHEMICAL REACTIONS • Precipitation reactions – mix two ionic substances and get a solid ionic substance (precipitate). • Acid-base reaction. An acid reacts with base, transfer of a proton. • Oxidation-reduction reactions – transfer of electrons between reactants.

  7. 4.3 PRECIPITATION REACTIONS • Occurs in aqueous solution. • One product is insoluble. PREDICTING PRECIPITATION REACTIONS MgCl2 + AgNO3  Exchangereaction: rxn. between compounds that, when written as a molecular equation, appears to involve the exchange of parts between the two reactants.

  8. Exchange the anions between the two reactants (remember anions are negative ions and cations are positive ions). MgCl2 + 2AgNO3 MgCl2 + 2AgNO3 2AgCl + Mg(NO3)2 Which one is the precipitate? Check rules in book…

  9. MgCl2 + 2AgNO3 2AgCl + Mg(NO3)2 Rule 3: silver chloride is one of the exceptions to the general solubility of chlorides. We predict silver chloride is insoluble. Magnesium nitrate is soluble: Rule 2 So AgCl must be the precipitate. Show this in the following equation: MgCl2(aq) + 2AgNO3(aq) 2AgCl(s) + Mg(NO3)2(aq)

  10. To see this occur on an ionic level, we will rewrite molecular equation as a net ionic equation. Molecular equation: MgCl2(aq) + 2AgNO3(aq) 2AgCl(s) + Mg(NO3)2(aq) Ionic equation: Mg2+(aq) + 2Cl-(aq) + 2Ag+(aq) + 2NO3-(aq) 2AgCl(s) + Mg2+(aq) + 2NO3-(aq)

  11. Mg2+(aq) + 2Cl-(aq) + 2Ag+(aq) + 2NO3-(aq) 2AgCl(s) + Mg2+(aq) + 2NO3-(aq) Mg2+(aq) + 2Cl-(aq) + 2Ag+(aq) + 2NO3-(aq) 2AgCl(s) + Mg2+(aq) + 2NO3-(aq) Ag+(aq) + Cl-(aq)AgCl(s) If silver chloride were soluble, a rxn. would not have occurred. AgCl is removed from the reaction mixtures as an insoluble compound. Leaves behind a solution of Mg(NO3)2

  12. Example 4.3: Deciding Whether Precipitation Occurs For each of the following, decide whether a precipitation reaction occurs. If it does, write the balanced molecular equation and then the net ionic equation. If no reaction occurs, write the compounds followed by an arrow and then NR (no reaction).

  13. Aqueous solutions of sodium chloride and iron(II) nitrate are mixed. NaCl + Fe(NO3)2 Exchange anions: NaCl + Fe(NO3)2 NaNO3 + FeCl2(notbalanced) Refer to Table 4.1 (NaCl, NaNO3, iron(II) nitrate, and iron(II) chloride are soluble) No precipitate, no reaction occurs! NaCl(aq) + Fe(NO3)2(aq) NR

  14. Aqueous solutions of aluminum sulfate and sodium hydroxide are mixed. Al2(SO4)3 + NaOH Exchange anions Al2(SO4)3 + NaOH Al(OH)3 + Na2SO4 (not balanced) From table 4.1, Al2(SO4)3 is soluble and NaOH and Na2SO4 are soluble, and Al(OH)3 is insoluble. Aluminum hydroxide precipitates. Al2(SO4)3(aq) + 6NaOH(aq) 2Al(OH)3(s) + 3Na2SO4(aq)

  15. To get the net ionic equation, you write the soluble ionic compounds as ions and cancel spectator ions. 2Al3+(aq) + 3SO42-(aq) + 6Na+(aq) + 6OH-(aq)  2Al(OH)3(s) + 6Na+(aq) + 3SO42-(aq) Net ionic equation is: Al3+(aq) + 3OH-(aq)  Al(OH)3(s) Thus aluminum ion reacts with hydroxide ion to precipitate aluminum hydroxide

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