6. Chemical Quantities & Aqueous Reactions

Which element is being reduced in the following reaction? 

Cr₂O₇^2- + 3 HNO₂ + 5 H⁺ → 2 Cr³⁺ +  3NO₃^- + 4 H₂O

Identify the oxidizing agent and reducing agent from the following redox reaction. 

Ba (s) + Cl₂ (g) → BaCl₂ (aq)

Which element is oxidized and which is reduced in the following reaction?

Hg (aq) + HgCl₂ (aq) → Hg₂Cl₂

Which of the following represents an oxidation-reduction reaction? 

I. PCl₃ (aq) + Cl₂ (g) → PCl₅ (aq) 

II. 2 AgNO₃ (aq) + Cu (s) → Cu(NO₃)₂ (aq) + 2 Ag (s) 

III. CO₂ (g) + 2 LiOH (aq) → Li₂CO₃ (aq) + H₂O (l)

IV. FeCl₂ (aq) + 2 NaOH (aq) → Fe(OH)₂ (aq) + 2 NaCl (aq) 

3 PbO (s) + 2 NH₃ (aq) → N₂ (g) + 3 H₂O (l) + 3 Pb (s)

In the Brønsted–Lowry concept of acids and bases, acid– base reactions are viewed as proton-transfer reactions. The stronger the acid, the weaker is its conjugate base. If we were to think of redox reactions in a similar way, what particle would be analogous to the proton? Would strong oxidizing agents be analogous to strong acids or strong bases? [Sections 20.1 and 20.2]

(b) On which side of an oxidation half-reaction do the electrons appear?

Indicate whether each of the following statements is true or false: (c) If there are no changes in the oxidation state of the reactants or products of a particular reaction, that reaction is not a redox reaction.

Indicate whether each of the following statements is true or false: (a) If something is oxidized, it is formally losing electrons.

Hydrazine 1N2H42 and dinitrogen tetroxide 1N2O42 form a self-igniting mixture that has been used as a rocket propellant. The reaction products are N2 and H2O. (c) Which substance serves as the reducing agent and which as the oxidizing agent?

Which element is oxidized, and which is reduced in the following reactions? (c) Cl21aq2 + 2 NaI1aq2¡I21aq2 + 2 NaCl1aq2

Which element is oxidized, and which is reduced in the following reactions? (b) 3 Fe1NO3221aq2 + 2 Al1s2¡3 Fe1s2 + 2 Al1NO3231aq2

Which element is oxidized, and which is reduced in the following reactions? (a) N21g2 + 3 H21g2¡2 NH31g2

Which of the following are redox reactions? For those that are, indicate which element is oxidized and which is reduced. For those that are not, indicate whether they are precipitation or neutralization reactions. (a) P41s2 + 10 HClO1aq2 + 6 H2O1l2¡ 4 H3PO41aq2 + 10 HCl1aq2

The accompanying photo shows the reaction between a solution of Cd(NO₃)₂ and one of Na₂S. (d) Is this a redox reaction?

The commercial production of nitric acid involves the following chemical reactions:

4 NH₃(g) + 5 O₂(g) → 4 NO(g) + 6 H₂O(g)

2 NO(g) + O₂(g) → 2 NO₂(g)

3 NO₂(g) + H₂O(l) → 2 HNO₃(aq) + NO(g)

(b) Identify the element undergoing oxidation and the element undergoing reduction. 3 NO₂(g) + H₂O(l) → 2 HNO₃(aq) + NO(g)

The commercial production of nitric acid involves the following chemical reactions:

4 NH₃(g) + 5 O₂(g) → 4 NO(g) + 6 H₂O(g)

2 NO(g) + O₂(g) → 2 NO₂(g)

3 NO₂(g) + H₂O(l) → 2 HNO₃(aq) + NO(g)

(a) Which of these reactions are redox reactions?

Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxidation states are Au+1aq2 + e- ¡ Au1s2 Ered ° = +1.69 V Au3+1aq2 + 3 e- ¡ Au1s2 Ered ° = +1.50 V (c) Miners obtain gold by soaking gold-containing ores in an aqueous solution of sodium cyanide. A very soluble complex ion of gold forms in the aqueous solution because of the redox reaction 4 Au1s2 + 8 NaCN1aq2 + 2 H2O1l2 + O21g2 ¡ 4 Na3Au1CN2241aq2 + 4 NaOH1aq2 What is being oxidized, and what is being reduced in this reaction?

Disulfides are compounds that have S ¬ S bonds, like peroxides have O ¬ O bonds. Thiols are organic compounds that have the general formula R ¬ SH, where R is a generic hydrocarbon. The SH- ion is the sulfur counterpart of hydroxide, OH-. Two thiols can react to make a disulfide, R ¬ S ¬ S ¬ R. (c) If you react two thiols to make a disulfide, are you oxidizing or reducing the thiols?

Aqueous solutions of ammonia 1NH32 and bleach (active ingredient NaOCl) are sold as cleaning fluids, but bottles of both of them warn: 'Never mix ammonia and bleach, as toxic gases may be produced.' One of the toxic gases that can be produced is chloroamine, NH2Cl. (e) Is N oxidized, reduced, or neither, upon the conversion of ammonia to nitrogen trichloride?

A substance with the potential to cause reduction in another substance is __________.

A substance with the potential to cause oxidation in another substance is __________.

Which of the following is true about a redox reaction? In a redox reaction, the reducing agent loses electrons. In a redox reaction, the oxidizing agent loses electrons. In a redox reaction, the oxidized species gains electrons. In a redox reaction, the reduced species loses electrons.

Identify the oxidizing agent and the reducing agent for 4Li(s) + O₂(g) → 2Li₂O(s)

What element is being reduced in the following redox reaction? Cr(OH)₄^-(aq) + ClO^-(aq) → CrO₄^2-(aq) + Cl^-(aq)

Which element is oxidized in this reaction? Fe₂O₃ + 3CO → 2Fe + 3CO₂

Which element is reduced in this reaction? 2KMnO₄ + 3Na₂SO₃ + H₂O → 2MnO₂ + 3Na₂SO₄ + 2KOH

Which substance is the oxidizing agent in this reaction? 2CuO + C → 2Cu + CO₂

A chemical reaction that has the general formula of AB → A + B is best classified as what type of reaction?

Identify the oxidizing agent and the reducing agent for 4Li(s) + O₂(g) → 2Li₂O(s).

Which of the following is true about a redox reaction? In a redox reaction, the reducing agent loses electrons. In a redox reaction, the oxidizing agent loses electrons. In a redox reaction, the oxidized species gains electrons. In a redox reaction, the reduced species loses electrons.

The presence of which reactant is the best indicator of an oxidation-reduction reaction?

in a reaction, a molecule loses an electron. this is an example of which type of reaction?

Use the information in the aleks data tab to sort the following chemical species by reducing power.

Cl₂(g)+ 2 F⁻(aq) → F₂(g) + 2 Cl⁻(aq)

Which element is oxidized in this reaction? ZNO + C --> ZN + CO

Which type of reaction has the general formula of AB + CD → AD + CB?

What is it called when a substance loses an electron and oxygen is acquired?

In redox reactions, the reactant that is oxidized is also called the _________.

Oxidation involves the ________, and reduction involves the

In the reaction shown below, which substance is oxidized? 2 Cr(s) + Fe₂O₃(aq) → Cr₂O₃(aq) + 2 Fe(s)

When a(n) _________ agent oxidizes, it causes reduction in another substance.