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Ionic Equations & Reactions. Equations Molecular equations – show the complete chemical formulas. Does not indicate ionic character Complete ionic equation.

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Presentation on theme: "Ionic Equations & Reactions. Equations Molecular equations – show the complete chemical formulas. Does not indicate ionic character Complete ionic equation."— Presentation transcript:

1 Ionic Equations & Reactions

2 Equations Molecular equations – show the complete chemical formulas. Does not indicate ionic character Complete ionic equation – shows all ions. Actually how the particles exist in the solution

3 Steps for Writing Ionic Equations 1.Write the balances molecular equation (balanced chemical equation) 2.Break every thing down into its ions EXCEPT the solid, gas, water, or weak electrolyte (complete ionic equation) 3.Cross out everything that is the same on both sides (spectator ions) 4.Write what is left (net ionic equation)

4 Rules When writing ionic equations, you must keep together the solid, gas, water, or weak electrolyte Spectator ions – ions that appear on both sides of the equation. They have very little to do with the chemical reaction

5 Example Write the balanced chemical equation, the complete ionic equation, and the net ionic equation for the reaction between lead (II) nitrate and potassium iodide

6 Example Write the balanced chemical equation Pb(NO 3 ) KI PbI KNO 3 You MUST identify the solid, gas, or water Pb(NO 3 ) KI PbI 2 (s) + 2 KNO 3 Balanced chemical equation

7 Example Now break every thing except the solid, gas, or water into its ions Remember ions are things with charges Everything will be broken down into one positive charge and one negative charge

8 Example Pb(NO 3 ) KI PbI 2 (s) + 2 KNO 3 Pb NO K I -1 PbI 2 (s) + 2K NO 3 -1 Complete ionic Equation

9 Example Now cross out everything that is the same on both sides (spectator ions) Pb NO K I -1 PbI 2 (s) + 2K NO 3 -1 Now write what is left Pb I -1 PbI 2 (s) Net ionic equation

10 Another Example Write the balanced chemical equation, complete ionic equation, and net ionic equation for the reaction between calcium chloride and sodium acetate

11 Another Example Balanced chemical equation CaCl 2 + Na 2 CO 3 CaCO 3 (s) + 2NaCl Complete ionic equation Ca Cl Na +1 + CO 3 -2 CaCO 3 (s) + 2Na Cl -1 Net Ionic Equation Ca Cl Na +1 + CO 3 -2 CaCO 3 (s) + 2Na Cl -1 Ca +2 + CO 3 -2 CaCO 3 (s)

12 What if water is formed? Write the balanced chemical equation, complete ionic equation, and net ionic equation for the reaction between Calcium hydroxide and nitric acid

13 Example with water Balanced chemical equation Ca(OH) HNO 3 Ca(NO 3 ) HOH Complete ionic equation Ca (OH) H NO 3 -1 Ca NO HOH Net Ionic Equation Ca (OH) H NO 3 -1 Ca NO HOH 2(OH) H +1 2 HOH

14 5 Major Types of Reactions We will be discussing 5 major types of reactions 1.Synthesis 2.Decomposition 3.Single Replacement 4.Double Replacement 5.Combustion You need to know these reactions! Note cards are an extremely effective way to remember them

15 Synthesis # 1 1.Metal oxide + nonmetal oxide metal oxyanion (NO ions – No Redox) No Redox simply means that the oxidation numbers of the elements stays the same

16 Synthesis # 1 Example Sulfur dioxide gas is passed over solid calcium oxide SO 2 + CaO We know that we have to get a metal oxyanion. So we either get CaSO 4 or CaSO 3 We need to check the oxidation states on sulfur to see which one is the same.

17 Synthesis # 1 Example In SO 2, the oxidation number of O is -2 So the oxidation number of S must be +4 Our product choices are CaSO 3 or CaSO 4 In CaSO 3 …S has an oxidation # of +4 In CaSO 4 …S has an oxidation # of +6 Therefore the product must be CaSO 3 SO 2 + CaO CaSO 3

18 Synthesis # 2 2.Metal oxide + water strong base (IONS) Strong acids & bases ionize completely in water & are therefore electrolytes. They will be written as ions Strong bases…Group !a or 2A hydroxides There are 7 strong acids… HCl, HBr, HI, HNO 3, HClO 3, HClO 4, H 2 SO 4 You MUST know these!

19 Synthesis # 2 Example Solid sodium oxide is added to water Na 2 O + H 2 O Na 2 O + H 2 O NaOH Na 2 O + H 2 O 2NaOH Na 2 O stays together because it is solid H 2 O stays together because it is water NaOH is separated because it is a strong base Na 2 O + H 2 O 2Na + + OH -

20 Synthesis # 3 3.Non metal oxide + water oxyacid (weak molecules…strong ions…No Redox) Sulfur dioxide gas is placed in water SO 2 + H 2 O We are going to get an oxyacid…so we either have H 2 SO 3 or H 2 SO 4 The S needs to have the same oxidation number

21 Synthesis # 3 Example In SO 2, O has an oxidation # of -2…so S has an oxidation # of +4 In H 2 SO 3 …S has an oxidation # of +4 In H 2 SO 4 …S has an oxidation # of +6 Therefore we will get In H 2 SO 3 SO 2 + H 2 O H 2 SO 3 Since H 2 SO 3 is a weak acid…we will keep it together

22 Synthesis # 4 4.Metal + nonmetal salt (NO ions) A salt is just an ionic compound ( a positive charge & a negative charge) Magnesium metal is combusted in nitrogen gas Mg + N 2 Mg + N 2 Mg 3 N 2 3Mg + N 2 Mg 3 N 2

23 Decomposition # 1 1.Metal oxyanion metal oxide + nonmetal oxide (No Redox – NO ions) A solid sample of calcium sulfate is heated CaSO 4 CaSO 4 CaO + SO 3

24 Decomposition # 2 2.Base metal oxide + water (No Redox – NO ions) Calcium hydroxide is decomposed Ca(OH) 2 Ca(OH) 2 CaO + H 2 O

25 Single Replacement # 1 1.Metal + ionic solution Metal ion + metal (will have ions) Must look at activity series! Aluminum metal is added to a solution of copper (II) chloride Al + CuCl 2 Al + CuCl 2 AlCl 3 + Cu 2Al + 3CuCl 2 2AlCl 3 + 3Cu 2Al + 3Cu +2 2Al Cu

26 Single Replacement # 2 2.Active metal (Group 1A, Ba, Ca, Sr) + water H 2 + strong base (IONS) Sodium is placed in water Na + H 2 O Na + H 2 O H 2 + NaOH 2Na + 2H 2 O H 2 + 2NaOH 2Na + 2H 2 O H 2 + 2Na + + 2OH -

27 Single Replacement # 3 3.Halogen + metal halide new metal halide + halogen (REDOX…will have ions) Chlorine gas is bubbled into a solution of sodium bromide Cl 2 + NaBr Cl 2 + NaBr NaCl + Br 2 Cl 2 + 2NaBr 2NaCl + Br 2 Cl 2 + 2Br - 2Cl - + Br 2

28 Double Replacement # 1 1.Precipitate (must know solubility rules)…the precipitate will stay together A saturated solution of barium hydroxide is mixed with a solution of iron (III) sulfate Ba(OH) 2 + Fe 2 (SO 4 ) 3 Ba(OH) 2 + Fe 2 (SO 4 ) 3 Fe(OH) 3 + BaSO 4(s) 3Ba(OH) 2 + Fe 2 (SO 4 ) 3 2Fe(OH) 3 + 3BaSO 4(s) 3Ba SO BaSO 4(s)

29 Double Replacement # 2 2.Formation of a gas (acid + sulfide, carbonate, or bicarbonate) Hydrobromic acid is added to a solution of potassium bicarbonate HBr + KHCO 3 HBr + KHCO 3 H 2 CO 3 + KBr H 2 CO 3 ALWAYS breaks down into CO 2 + H 2 O HBr + KHCO 3 CO 2 + H 2 O + KBr H + + HCO 3 - CO 2 + H 2 O

30 Double Replacement # 3 3.Metal hydride + water H 2 + strong base (IONS) Sodium hydride is placed into water NaH + H 2 O NaH + H 2 O H 2 + NaOH NaH + H 2 O H 2 + Na + + OH -

31 Combustion 1.Hydrocarbon + O 2 CO 2 + H 2 O (No ions) Combustion of methane CH 4 + O 2 CO 2 + H 2 O CH 4 + 2O 2 CO 2 + 2H 2 O


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