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Reaction Predictions. Most Commonly Used Cations and Anions Hydrogen H + Hydrogen H + Sodium Na + Sodium Na + Potassium K + Potassium K + Calcium Ca +

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Presentation on theme: "Reaction Predictions. Most Commonly Used Cations and Anions Hydrogen H + Hydrogen H + Sodium Na + Sodium Na + Potassium K + Potassium K + Calcium Ca +"— Presentation transcript:

1 Reaction Predictions

2 Most Commonly Used Cations and Anions Hydrogen H + Hydrogen H + Sodium Na + Sodium Na + Potassium K + Potassium K + Calcium Ca + ² Calcium Ca + ² Magnesium Mg + ² Magnesium Mg + ² Iron (Ferrous) Fe + ² Iron (Ferrous) Fe + ² Iron (Ferric) Fe + ³ Iron (Ferric) Fe + ³ Hydroxide OHˉ Chloride Clˉ Sulfide Sˉ² Bicarbonate HCOзˉ Carbonate COзˉ² Sulfate SO 4 ˉ² Phosphate PO 4 ˉ³

3 Cations/ Anions, contd. You can figure out the charge of an ion by using the periodic table. For Example: You can figure out the charge of an ion by using the periodic table. For Example: Alkali metals such as Lithium can easily lose an electron to become stable (just like a Noble gas) so taking away an electron give Lithium a +1 charge. Alkali metals such as Lithium can easily lose an electron to become stable (just like a Noble gas) so taking away an electron give Lithium a +1 charge. On the other hand Halogens can easily accept an electron to become stable. Accepting an electron gives halogens a -1 charge. On the other hand Halogens can easily accept an electron to become stable. Accepting an electron gives halogens a -1 charge.

4 Practice What is the oxidation state of Oxide? What is the oxidation state of Oxide? What is the oxidation state of Iodide? What is the oxidation state of Iodide? What is the oxidation state of a Calcium ion? What is the oxidation state of a Calcium ion? What is the oxidation state of a Lithium ion? What is the oxidation state of a Lithium ion?

5 Answers -2 -2 -1 -1 +2 +2 +1 +1

6 Net Ionic Equation To create a net ionic equation, you break apart all ionic molecules in a balanced molecular equation into their ions if they are soluble. To create a net ionic equation, you break apart all ionic molecules in a balanced molecular equation into their ions if they are soluble. If there are spectator ions, ions that appear on both sides of the equation, they cancel each other. If there are spectator ions, ions that appear on both sides of the equation, they cancel each other.

7 Net Ionic Example Silver nitrate is mixed with potassium chromate Silver nitrate is mixed with potassium chromate –2AgNO 3 + K 2 CrO 4 → Ag 2 CrO 4 + 2KNO 3 Molecular Equation –2Ag + + 2NO 3 ˉ + 2K + + CrO 4 -2 → Ag 2 CrO 4 + 2K + + 2NO 3 -2 Complete ionic equation –2Ag + + CrO 4 -2 → Ag 2 CrO 4 Net Ionic Equation

8 Solubility Rules NO 3 - all nitrates are soluble NO 3 - all nitrates are soluble CH3COO - or C 2 H 3 O 2 - CH3COO - or C 2 H 3 O 2 - all acetates are soluble except AgCH 3 COO ClO 3 - all chlorates are soluble ClO 3 - all chlorates are soluble Cl - all chlorides are soluble except AgCl, Hg 2 Cl 2, PbCl 2 Cl - all chlorides are soluble except AgCl, Hg 2 Cl 2, PbCl 2 Br - all bromides are soluble except AgBr, PbBr 2, Hg 2 Br 2, and HgBr 2 Br - all bromides are soluble except AgBr, PbBr 2, Hg 2 Br 2, and HgBr 2 I - all iodides are soluble except AgI, Hg 2 I 2, HgI, and PbI 2 I - all iodides are soluble except AgI, Hg 2 I 2, HgI, and PbI 2

9 Solubility Rules, contd. SO4¯²all sulfates are soluble except BaSO4, PbSO4, Hg2SO4, CaSO4, AgSO4 and SrSO4 SO4¯²all sulfates are soluble except BaSO4, PbSO4, Hg2SO4, CaSO4, AgSO4 and SrSO4 Alkali metal, cations, and NH 4 – all are soluble Alkali metal, cations, and NH 4 – all are soluble H + all common inorganic acids and low molecular mass organic acids are soluble H + all common inorganic acids and low molecular mass organic acids are soluble

10 (In)Soubility Rules, contd. CO 3 - ² all carbonates are insoluble except those of alkali metals and NH 4 CO 3 - ² all carbonates are insoluble except those of alkali metals and NH 4 CrO 4 - ² all chromates are insoluble except those of alkali metals, NH 4, CaCrO 4, and SrCO 4 CrO 4 - ² all chromates are insoluble except those of alkali metals, NH 4, CaCrO 4, and SrCO 4 OH - all hydroxides are insoluble except those of the alkali metals, NH 4, Ba(OH) 2, Sr(OH) 2, and Ca(OH) 2 OH - all hydroxides are insoluble except those of the alkali metals, NH 4, Ba(OH) 2, Sr(OH) 2, and Ca(OH) 2 PO 4 - ³ all phosphates are insoluble except those of alkali metals and NH 4 PO 4 - ³ all phosphates are insoluble except those of alkali metals and NH 4 SO 3 - ² all sulfites are insoluble except those of alkali metals and NH 4 SO 3 - ² all sulfites are insoluble except those of alkali metals and NH 4 S - ² all sulfides are insoluble except those of alkali metals and NH 4 S - ² all sulfides are insoluble except those of alkali metals and NH 4

11 Synthesis Synthesis occurs when two or more reactants combine to form a single product. There are several common types of synthesis reaction. Synthesis occurs when two or more reactants combine to form a single product. There are several common types of synthesis reaction. You know it happens when you have: You know it happens when you have: -A metal combines with a nonmetal to form a bianary salt. -A piece of lithium metal is dropped into a container of nitrogen gas. -A piece of lithium metal is dropped into a container of nitrogen gas. 6Li+ N 2  2Li 3 N -Metal oxide and water forms a base (metallic hydroxide) -Solid sodium oxide is added to water. -Solid sodium oxide is added to water. Na 2 O + H 2 O  2NaOH

12 Synthesis, contd. Nonmetal oxide and water forms acids. Nonmetal retains its oxidation number. Nonmetal oxide and water forms acids. Nonmetal retains its oxidation number. -Carbon dioxide is burned in water. -Carbon dioxide is burned in water. CO 2 + H 2 O  H 2 CO 3 Metallic oxides and nonmetallic oxides form salts. Metallic oxides and nonmetallic oxides form salts. -Solid sodium oxide is added to carbon dioxide. -Solid sodium oxide is added to carbon dioxide. Na 2 O + CO 2  Na 2 CO 2

13 Decomposition Occurs when a single reactant is broken down into two or more products. Occurs when a single reactant is broken down into two or more products. The reactions react to form basic compounds or elements. The reactions react to form basic compounds or elements. When a compound is heated or electrolyzed, it means that it is broken up into its ions. When a compound is heated or electrolyzed, it means that it is broken up into its ions. AB  A+B AB  A+B

14 Examples of Decomposition A sample of magnesium carbonate is heated. MgCO 3  MgO + CO 2 A sample of magnesium carbonate is heated. MgCO 3  MgO + CO 2 Molten sodium chloride is electrolyzed. 2NaCl  2Na + Cl 2 Molten sodium chloride is electrolyzed. 2NaCl  2Na + Cl 2 A sample of ammonium carbonate is heated. (NH 4 ) 2 CO 3  2NH 3 + H 2 O + CO 2 A sample of ammonium carbonate is heated. (NH 4 ) 2 CO 3  2NH 3 + H 2 O + CO 2

15 Single Replacement Reactions that involve an element replacing one part of a compound. The products include the displace element and a new compound. An element can only replace another element that is less active than itself. (Look a activity series/ AP packet) Reactions that involve an element replacing one part of a compound. The products include the displace element and a new compound. An element can only replace another element that is less active than itself. (Look a activity series/ AP packet) A +BX  B+AX A +BX  B+AX

16 Single Replacement Rules 1. Active metals replace less active metals from the less active metals’ compounds in aqueous solutions ex. 3Mg+ 2FeCl 3 —> 2Fe + 3MgCl 2 2. Active metals replace hydrogen in water ex. 2Na + 2H 2 O —> H 2 + 2NaOH 3. Active metals replace hydrogen in acids ex. 2Li + 2HCl —> H 2 + 2LiCl

17 Single Replacement Rules, contd. 4. Active nonmetals replace less active nonmetals from their compounds in aqueous solutions ex. Cl 2 + 2KI —> I 2 + 2KCl 5. If a less reactive element is combined with a more reactive element in compound form, there will be no reaction ex. Cl 2 + KF —> no reaction* * On the AP test reactions will ALWAYS have products; it will never be “no reaction.”

18 Activity Series (Single Replacement) Metals Metals –Li, Ca, Na, Mg, Al, Zn, Fe, Pb, [H 2 ], Cu, A g, Pt –Li, Ca, Na, Mg, Al, Zn, Fe, Pb, [H 2 ], Cu, A g, Pt Nonmetals Nonmetals –F 2, Cl 2, Br 2, I 2, More active  Less Active

19 Double Replacement Two compounds react to form two new compounds. No changes in oxidation numbers occur. Two compounds react to form two new compounds. No changes in oxidation numbers occur. Each cation pairs up with the anion in the other compound. Each cation pairs up with the anion in the other compound. The “driving force” in these reactions is the removal of at least one pair of ions from solution. The “driving force” in these reactions is the removal of at least one pair of ions from solution. This removal of ions happens with the formation of a precipitate, gas, or molecular species. This removal of ions happens with the formation of a precipitate, gas, or molecular species. When a double replacement reaction doesn’t go to completion, it is a reversible reaction (no ions have been removed). When a double replacement reaction doesn’t go to completion, it is a reversible reaction (no ions have been removed). AX+ BY  AY+ BX AX+ BY  AY+ BX

20 How do you know a double replacement reaction occurs? The reactants will contain a(n): The reactants will contain a(n):-gas -insoluble precipitate -molecular species *Remember– on the AP test the reaction will always occur

21 Common Gases Released (Dbl. Repl.) H 2 S Any sulfide plus any acid forms H2S and a salt. H 2 S Any sulfide plus any acid forms H2S and a salt. CO 2 Any carbonate plus any acid form CO 3, water, and a salt. CO 2 Any carbonate plus any acid form CO 3, water, and a salt. SO 2 Any sulfite plus any acid form SO 2, water, and a salt. SO 2 Any sulfite plus any acid form SO 2, water, and a salt. NH 3 Any ammonium plus a soluble hydroxide form NH 3, water, and a salt. NH 3 Any ammonium plus a soluble hydroxide form NH 3, water, and a salt.

22 Acid/ Base Reactions (Dbl. Repl.) An acid and a base will react and form water and a salt. An acid and a base will react and form water and a salt. Hydrochloric acid is added to sodium hydroxide. HCl + NaOH  NaCl + H 2 O Hydrochloric acid is added to sodium hydroxide. HCl + NaOH  NaCl + H 2 O

23 Hydrolysis (Dbl. Repl.) It is the reverse of neutralization and results when a salt plus a water molecule yields an acid plus a base. It is the reverse of neutralization and results when a salt plus a water molecule yields an acid plus a base. Salt + water  acid + base Salt + water  acid + base Key things to know about hydrolysis reactions: Key things to know about hydrolysis reactions: –Salts of a strong acid plus a weak base will hydrolyze into an acidic solution. NH 4 + +Cl - +H 2 O → H + +Cl - + (NH) 4 OH NH 4 + +Cl - +H 2 O → H + +Cl - + (NH) 4 OH –Salts of a weak acid and a strong base will always hydrolyze to give a basic solution. K + +F - +H 2 O → K + +OH - +HF K + +F - +H 2 O → K + +OH - +HF –Salts of a strong acid and a strong base will never undergo hydrolysis and therefore make a neutral solution. Na + +Cl - +H 2 O → Na + +OH - +H + Cl - Na + +Cl - +H 2 O → Na + +OH - +H + Cl - –Salts of a weak acid plus salts of a weak base may hydrolyze as an acid, base, or a neutral solution; the final result depends on the Ka’s and Kb’s of the acids and bases formed during the hydrolysis process. Disclaimer!! The spectator ions were not removed Disclaimer!! The spectator ions were not removed

24 Examples of Dbl. Replacement Solutions of potassium bromide and silver nitrate are mixed. Solutions of potassium bromide and silver nitrate are mixed. KBr + AgNO 3  AgBr + KNO 3 A solution of sodium sulfate is added to a solution of hydrochloric acid. Na 2 SO 3 + 2HCl  2NaCl + H 2 SO 3 A solution of sodium sulfate is added to a solution of hydrochloric acid. Na 2 SO 3 + 2HCl  2NaCl + H 2 SO 3

25 Hydrolysis Sample Problems Try these: Try these: –An aqueous solution of manganese (II) sulfate undergoes hydrolysis. –Ammonium fluoride and water are mixed together.

26 Hydrolysis answers –MnSO 4 + 2H 2 O → H 2 SO 4 + Mn(OH) 2 –NH 4 F + H 2 O → HF + NH 4 OH

27 Combustion (Organic Reacs.) An organic compound reacts with O 2 to form water and carbon dioxide. An organic compound reacts with O 2 to form water and carbon dioxide. If something is burned there is a combustion reaction. If something is burned there is a combustion reaction. Methanol is burned in oxygen gas. 2CH 3 OH + 3O 2  4H 2 O + 2CO 2 Methanol is burned in oxygen gas. 2CH 3 OH + 3O 2  4H 2 O + 2CO 2

28 Addition (Organic Reacs.) A halogen or hydrogen is added to an alkene or alkyne, breaking apart the double or triple bonds and forming single bonds. A halogen or hydrogen is added to an alkene or alkyne, breaking apart the double or triple bonds and forming single bonds. Fluorine is added to ethene F 2 + CH 2 =CH 2  CH 2 F-CH 2 F Fluorine is added to ethene F 2 + CH 2 =CH 2  CH 2 F-CH 2 F

29 Substitution (Organic Reacs.) An atom attached to a carbon is removed and something else takes its place. An atom attached to a carbon is removed and something else takes its place. Bromine is added to methane Br 2 + CH 4  CH 3 Br + HBr Bromine is added to methane Br 2 + CH 4  CH 3 Br + HBr

30 Oxidizing Agents (Redox Reacs.) Common Oxidizing Agents MnO 4 ¯ in acidic solution MnO 4 ¯ in acidic solution MnO 2 in acidic solution MnO 2 in acidic solution MnO 4 ¯ in neutral or basic solution MnO 4 ¯ in neutral or basic solution Cr 2 O 7 ˉ² in acidic solution Cr 2 O 7 ˉ² in acidic solution HNO 3, concentrated HNO 3, concentrated HNO 3, dilute HNO 3, dilute H 2 SO 4, hot, concentrated H 2 SO 4, hot, concentrated Metallic ions (higher oxidation #) Metallic ions (higher oxidation #) Free halogens Free halogens Na 2 O 2 Na 2 O 2 HClO 4 HClO 4 C 2 O 4 ˉ² C 2 O 4 ˉ² H 2 O 2 H 2 O 2 Products Formed Mn+² MnO 2 (s) Cr+³ NO 2 NO SO 2 Metallous ions (lower oxidation #) Halide ions NaOH Clˉ CO 2 O 2

31 Reduction Agents (Redo Reacs.) Common Reducing Agents Halide ions Halide ions Free metals Free metals Sulfite ions or SO 2 Sulfite ions or SO 2 Nitrite ions Nitrite ions Free halogens, dilute basic solution Free halogens, dilute basic solution Free halogens, concentrated basic solution Free halogens, concentrated basic solution Metallous ions (lower oxidation #) Metallous ions (lower oxidation #) Products Formed Free halogen Metal ions Sulfate ions Nitrate ions Hypohalite ions Halite ions Metallic ions (higher oxidation #)

32 Electrolysis (Redox Reacs.) An electrolysis reaction is a reaction in which a non- spontaneous redox reaction is brought about by the passage of current under sufficient external electrical potential. The devices in which electrolysis reactions occur are called electrolytic cells. An electrolysis reaction is a reaction in which a non- spontaneous redox reaction is brought about by the passage of current under sufficient external electrical potential. The devices in which electrolysis reactions occur are called electrolytic cells. In theory, E° values (Standard Reduction Potentials) can be used to predict which element will plate out at a particular electrode when various solutions are combined. In theory, E° values (Standard Reduction Potentials) can be used to predict which element will plate out at a particular electrode when various solutions are combined. (B&L text) (B&L text)

33 Rules for Predicting Cathode Reactions (Reduction) When a direct electric current is passed through a water solution of an electrolyte, two possible reduction processes may occur at the cathode. When a direct electric current is passed through a water solution of an electrolyte, two possible reduction processes may occur at the cathode. The cation may be reduced to the corresponding metal. The cation may be reduced to the corresponding metal. M n+ + ne -  M(s) (reaction 1) n = (charge of cation) n = (charge of cation) Water molecule may be reduced to elementary hydrogen Water molecule may be reduced to elementary hydrogen 2H 2 O + 2eˉ  H2 + 2OHˉ (reaction 2)

34 Rules for Predicting Cathode Reactions, contd. For salts containing transition metal cations, which are relatively easy to reduced compared to water, reaction #1 will occur at the cathode (and the transition metal will plate out). For salts containing transition metal cations, which are relatively easy to reduced compared to water, reaction #1 will occur at the cathode (and the transition metal will plate out). M n+ + ne -  M(s) If the cation is representative metal, the water molecules will be easier to reduce compared to the cation, and reaction #2 will occur at the cathode, producing hydrogen gas and hydrogen ions. If the cation is representative metal, the water molecules will be easier to reduce compared to the cation, and reaction #2 will occur at the cathode, producing hydrogen gas and hydrogen ions. 2H 2 O + 2eˉ  H2 + 2OHˉ

35 Rules for Predicting Anode Reaction (oxidation) The oxidation process that occurs at the anode of an electrolytic cell operating in aqueous solution may be one of two oxidation processes. The oxidation process that occurs at the anode of an electrolytic cell operating in aqueous solution may be one of two oxidation processes. The anion may be oxidized to the corresponding nonmetal. The anion may be oxidized to the corresponding nonmetal. - 2Xˉ  X 2 + 2eˉ (reaction 1) Water molecules may be oxidized to elementary oxygen. Water molecules may be oxidized to elementary oxygen. - HOH  ½ O 2 + 2H + + 2eˉ (reaction 2)

36 Rules for Predicting Anode Reactions, contd. For salts containing iodide, bromide, or chloride ions, it is usually easier to oxidize these nonmetals rather than water. It will be found that the nonmetal is formed at the anode. For salts containing iodide, bromide, or chloride ions, it is usually easier to oxidize these nonmetals rather than water. It will be found that the nonmetal is formed at the anode. When the anion present is any other ion that is more difficult to oxidize than water, Reaction #2 will occur at the anode producing elementary oxygen and aqueous hydrogen ions. When the anion present is any other ion that is more difficult to oxidize than water, Reaction #2 will occur at the anode producing elementary oxygen and aqueous hydrogen ions.

37 Example Electrolysis Reactions 1. Copper (II) chloride in water Cu +2 + 2Clˉ  Cu + Cl 2 2. Copper (II) sulfate in water Cu +2 + HOH  Cu + ½ O 2 + 2H + 3. Sodium chloride in water 2Clˉ + 2HOH  H 2 + Cl 2 + 2OHˉ 4. Sodium sulfate in water 2HOH  2H 2 + O 2

38 Metals w/ Multiple Oxidation Levels (Redox Reacs.) These metals can change their oxidation state in a redox reaction These metals can change their oxidation state in a redox reaction –Antimony (III) or (V) –Bismuth (III) or (IV) –Cerium (III) or (IV) –Chromium (II) or (III) –Cobalt (II) or (III) –Copper (I) or (II) –Gallium (I) or (II) or (III) –Germanium (II) or (IV) –Gold (I) or (III) –Iron (II) or (III) –Lead (II) or (IV) –Mercury (I) or (II) –Nickel (II) or (III) –Thallium (I) or (III) –Thorium (II) or (IV) –Tin (II) or (IV) Tin (II) sulfate is added to iron (III) sulfate SnSO4 + Fe2(SO4)3  Sn(SO4)2 + 2FeSO4 Tin (II) sulfate is added to iron (III) sulfate SnSO4 + Fe2(SO4)3  Sn(SO4)2 + 2FeSO4

39 Complex Ion Reactions Nomenclature is on pages 23-27 of The Ultimate Chemical Equations Handbook Nomenclature is on pages 23-27 of The Ultimate Chemical Equations Handbook There are a lot of very complicated types of these reactions, but, for all intensive purposes and for the AP test, you only need to be familiar with those reactions pertaining to ammonia and water. There are a lot of very complicated types of these reactions, but, for all intensive purposes and for the AP test, you only need to be familiar with those reactions pertaining to ammonia and water. In a complex ion reaction, ligands will attach to a transition metal ion. In a complex ion reaction, ligands will attach to a transition metal ion. There will usually be twice as many ligands as the metals oxidation number There will usually be twice as many ligands as the metals oxidation number

40 Complex Ion Reactions, contd. These reactions usually occur in a concentrated solution of the ligand. These reactions usually occur in a concentrated solution of the ligand. Copper chloride (II) is added to a concentrated solution of ammonia Copper chloride (II) is added to a concentrated solution of ammonia –Cu 2+ +NH 3  [Cu(NH 3 ) 4 ] 2+

41 Common Reaction Terms Electrolysis: Electricity is run through a compound, resulting in a change of oxidation states. Electrolysis: Electricity is run through a compound, resulting in a change of oxidation states. Hydrolysis: The reaction of a salt with water to form molecular species. Salts of a strong acid + a weak base will always hydrolyze to give an acidic solution. Hydrolysis: The reaction of a salt with water to form molecular species. Salts of a strong acid + a weak base will always hydrolyze to give an acidic solution. Neutralization: Acid and base react to form a salt and water. Neutralization: Acid and base react to form a salt and water. Catalyst: A molecule that speeds that speeds a reaction but that does not appear in the reaction. Catalyst: A molecule that speeds that speeds a reaction but that does not appear in the reaction. Oxidation number: the charge that it would have if all the ligands (atoms that donate electrons) were removed along with the electron pairs that were shared with the central atom Oxidation number: the charge that it would have if all the ligands (atoms that donate electrons) were removed along with the electron pairs that were shared with the central atom

42 Common Reaction Terms, contd. Precipitate: an insoluble substance formed by the reaction of two aqueous substances. Precipitate: an insoluble substance formed by the reaction of two aqueous substances. Anode: the electrode where oxidation occursan ox Anode: the electrode where oxidation occursan ox Cathode: the electrode where reduction occursred cat Cathode: the electrode where reduction occursred cat


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