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II. Net Ionic Equations

This article explains the concept of net ionic equations, which are used to show only the ions involved in a reaction. It provides examples and guidelines for writing net ionic equations.

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II. Net Ionic Equations

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  1. Ch. 4 – Reactions II. Net Ionic Equations

  2. A. Equations Molecular Equation (written as whole formulas): ZnBr2 (aq) + 2 AgNO3 (aq) → Zn(NO3)2 + 2 AgBr (aq) means the compound is present as ions. • ZnBr2 (aq) Zn2+(aq) + 2 Br-(aq) • AgNO3 (aq) Ag+(aq) + NO3-(aq) • Also known as Dissociation Equations

  3. A. Equations • We can rewrite our molecular equation as a Complete Ionic Equation (shows dissolved electrolytes as ions): • Zn2+(aq) + 2 Br-(aq) + 2 Ag+(aq) + 2 NO3-(aq) • Zn2+(aq) + 2 NO3-(aq)+ 2 AgBr(s) Means solid which is insoluble compound

  4. B. Net Ionic Equations • Spectator ions: Ions that are present in a reaction but do not participate • The same on both the reactant and product side of the equation so they are “cancelled out”.

  5. B. Net Ionic Equations • Reactions in which the spectator ions have been removed are callednet ionic equations (shows only those ions that react). • 2 Ag+(aq) + 2 Br-(aq) → 2 AgBr(s) • A net ionic equation shows only the ions involved in the formation of the precipitate or solid, (s).

  6. B. Net Ionic Equations • Write the net ionic equation: • magnesium nitrate + sodium hydroxide • Write the chemical formulas • Predict the products • Balance the equation • Refer to a table of solubility to determine whether either, or both, of the two products will form insoluble precipitates. • Write ionic equations & net ionic equation.

  7. Work: • magnesium nitrate + sodium hydroxide

  8. B. Net Ionic Equations • Example: • Magnesium acetate + ammounium sulfate ? • Write the formulas • Predict the products • Balance the equation • Refer to a table of solubility to determine whether either of the two products will form insoluble precipitates.

  9. B. Net Ionic Equations • We find that both MgSO4 and NH4CH3COO are soluble compounds, meaning they will remain in solution and not form precipitates. • Thus, there is really NO REACTION occurring, since all ions simply remain in solution!

  10. C. Oxidation Numbers p.134 • Another way to say the “charge” • Enables us to identify elements that are oxidized and reduced • Fe(NO3)2 : Fe NO3 • MnO4- : Mn • KMnO4 : Mn • CrO4-2 : Cr • Cr2O7-2 : Cr

  11. Work: • Mercury (II) nitrate + sodium carbonate

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