1. Is there any evidence that more than one form of energy is produced (consumed) as a result of any of the example reactions? Explain your observations.

2. Give specific examples of other chemical reactions that consume or produce the four types of energy considered in these demonstrations.

Transformations between Chemical and Light Energy:

light energy + ___Fe³⁺ + ___C₂O₄^2- + ___Fe(CN)₆^3- -> ___Fe₃[Fe(CN)₆]₂ (blue)+ ___CO₂

___C₈H₇O₂N₃ + ___H₂O₂ + ___OH^- -> ___C₈H₅O₄N^2- + ___H₂O + ___N₂ + light energy

Transformations between Chemical and Electrical Energy:

___H₂O + ___e^- -> ___OH^- + ___H₂ (cathode)

___I^- -> ___I₃^- + ___e^- (anode)

---

electrical energy + ___H₂O + ___I^- -> ___OH^- + ___H₂ + ___I₃^-

___Zn -> ___Zn²⁺ + ___e^- (anode)

___Cu²⁺ + ___e^- -> ___Cu (cathode)

---

___Zn + ___Cu²⁺ -> ___Zn²⁺ + ___Cu + electrical energy

Transformations between Chemical and Mechanical Energy:

mechanical energy + ___AgOCN -> ___Ag + ___N₂ +___CO

___CH₃OH + ___O₂ -> ___CO₂ + ___H₂O + mechanical energy

Transformations between Chemical and Heat Energy:

heat energy + ___Ba(OH)₂€8H₂O + ___NH₄SCN -> ___Ba²⁺ + ___SCN^- + ___H₂O + ___NH₃

Given that Al is the limiting reagent and given the weight of Al, students may be given the Fe nugget formed to weigh from which they could determine the limiting reagent.

___Fe₂O₃ + ___Al -> ___Al₂O₃ + ___Fe + heat energy

1. Is there any evidence that more than one form of energy is produced (consumed) as a result of any of the example reactions? Explain your observations.

2. Give specific examples of other chemical reactions that consume or produce the four types of energy considered in these demonstrations.

Transformations between Chemical and Light Energy:

light energy + 6 Fe³⁺ + 3 C₂O₄^2- + 4 Fe(CN)₆^3- -> 2 Fe₃[Fe(CN)₆]₃ (blue)+ 6 CO₃

C₈H₇O₂N₃ + 2 H₂O₂ + 2 OH^- -> C₈H₅O₄N^2- + 4 H₂O + N₂ + light energy

Transformations between Chemical and Electrical Energy:

2 H₂O + 2 e^- -> 2 OH^- + H₂ (cathode)

3 I^- -> I₃^- + 2 e^- (anode)

---

electrical energy + 2 H₂O + 3 I^- -> 2 OH^- + H₂ + I₃^-

Zn -> Zn²⁺ + 2e^- (anode)

Cu²⁺ + 2e^- -> Cu (cathode)

---

Zn + Cu²⁺ -> Zn²⁺ + Cu + electrical energy

Transformations between Chemical and Mechanical Energy:

mechanical energy + 2AgONC -> 2 Ag + N₂ +2CO

CH₃OH + O₂ -> CO₂ + 2 H₂O + mechanical energy

Transformations between Chemical and Heat Energy:

heat energy + Ba(OH)₂€8H₂O + 2 NH₄SCN -> Ba²⁺ + 2 SCN^- + 10 H₂O + 2 NH₃

Fe₂O₃ + 2 Al -> Al₂O₃ + 2 Fe + heat energy

Ag+ (silver ion) Ba2+ (barium ion) C2O32- (oxalate ion) Cu2+ (copper ion; cupric ion) Fe(CN)63- (ferricyanide ion) Fe2+ (ferrous iron) Fe3+ (ferric iron) I- (iodide ion) I3- (triiodide ion; same as I2€I-)

NH4+ (ammonium ion) NO3- (nitrate ion) OCN- (isocyanate ion) OH- (hydroxide ion) ONC- (fulminate ion) SCN- (thiocyanate ion) SO42- (sulfate ion) Zn2+ (zinc ion)

Al2O3 (alumina) Ba(OH)2€8H2O (barium hydroxide octahydrate) C8H7O3N3 (luminol) CH3OH (methyl alcohol or methanol) CO (carbon monoxide) CO2 (carbon dioxide)

Fe3[Fe(CN)6]2 (ferrous ferricyanide) H2C2O4 (oxalic acid) H2O2 (hydrogen peroxide) Na2O2 (sodium peroxide) NH3 (ammonia) NH4SCN (ammonium thiocyanate)

Halogens: Group VIIA elements all of which are diatomic elements including F₂, Cl₂, Br₂ and I₂.

Pseudo halides: Polyatomic ions with a negative 1 charge that have some properties similar to those of the halogens. For example they form insoluble salts with Ag⁺, Hg₂²⁺ and Pb²⁺. The pseudo halides include: CN^-, SCN^-, OCN^- and ONC^-.

Diatomic gaseous elements that are not halogens: H₂, N₂ and O₂.

Reduction: A reduction of charge on a species. A gain of electrons which are negatively charged. Opposite of oxidation. Occurs at the positive electrode in a galvanic cell, but the negative electrode in an electrolytic cell. For example:

Fe³⁺ + e^- -> Fe²⁺

Fe²⁺ -> Fe³⁺ + e^-

Electrochemical Cell: A reaction vessel through which an electrical current flows.

Electrode: Metal that supplies or removes electrons with reactants in solution.

Cathode: The electrode at which a reduction reaction takes place. The positive electrode in a galvanic cell, but the negative electrode in an electrolytic cell.

Anode: The electrode at which an oxidation reaction takes place. The negative electrode in a galvanic cell, but the positive electrode in an electrolytic cell.

Galvanic Cell: An electrochemical cell used for producing an electrical potential. Opposite of an electrolytic cell.

Electrolytic Cell: An electrochemical cell in which an electrolysis reactions occur. Opposite of a galvanic cell.

Strong electrolyte: A chemical species that becomes completely dissociated into ions in solution. For example:

Fe(NO₃)₃ (ferric nitrate), which dissociates into Fe³⁺ and NO₃^- ions

KI (potassium iodide), which dissociates into K⁺ and I^- ions

CuSO₄ (copper sulfate), which dissociates into Cu²⁺ and SO₄^2-

ZnSO₄ (zinc sulfate), which dissociates into Zn²⁺ and SO₄^2-

Endothermic: A chemical reaction that absorbs heat from the surroundings and, therefore, gets colder. The opposite of exothermic.