a sad attempt to not completely fail the cumulative exam (chemistry)

Which best describes the oxidizing agent in this reaction?

Cl2(aq) + 2Br-(aq) --------- 2Cl-(aq) + Br2(aq)

Chlorine (Cl) is the oxidizing agent because it gains an electron.

During a redox reaction, the term reduction refers to

the gain of electrons.

Zn(s) + 2H+(aq) mc013-1.jpg Zn2+(aq) + H2(g) has an overall reduction potential of 0.76 V. Therefore,

the reaction is spontaneous and will proceed without any energy input.

Which type of reaction occurs in the following equation?

3ClO-(aq) ---- ClO-3(aq) + 2Cl-(aq) mc018-1.jpg

a disproportionation reaction

What is the reducing agent in the reaction below?

CrO3 + 2Al Cr + Al2O3

mc026-1.jpg

AI

Gold (Au) goes from an oxidation number of +3 to 0 in the reaction below.

2Au3+ + 6I- ----- 2Au + 3I2 mc006-1.jpg

What describes the Au3+ ion?

It is the oxidizing agent.

What is the reducing agent in the following reaction?

Cr3+ + 3Na ------ 3Na+ + Cr

mc028-1.jpg

Na because it loses electrons

In the reaction equation BrO-3(aq) --------- Br-(aq) + BrO-4(aq), how many oxidation states does the disproportionate substance have throughout the reaction?

3

In a disproportionation reaction, the disproportionate substance

has at least three oxidation states.

What is the overall reduction potential for the reaction Al3+(aq) + Mg(s) ------ Al(s) + Mg2+(aq) mc025-35.jpg

+0.71 V

Which reactants would lead to a spontaneous reaction?

Ag+ and Cu

Consider the half reaction below.

Cu2+(aq) + 2e- ------- Cu(s)

mc002-1.jpg

Which statement best describes what is taking place?

Copper is being reduced.

A student balances the following redox reaction using half-reactions.

Al + Mn2+ ------- Al3+ + Mn

mc031-1.jpg

How many electrons will be lost in all?

6

Consider the chemical reaction below.

Zn(s) + 2H+(aq) ------

Zn2+(aq) + H2(g) mc001-1.jpg

Which half reaction correctly represents reduction for this equation?

2H+(aq) + 2e- ------ H2(g) mc001-3.jpg

What is the purpose of finding oxidation states in the half-reaction method for balancing equations?

to identify the half reactions for the equation

Equations can be balanced by using the half-reaction method. Which step should be completed immediately after finding the oxidation states of atoms?

identifying the half reactions

Consider the redox reaction below.

Zn(s) + 2HCl(aq) --------

ZnCl2(aq) + H2(g) mc009-1.jpg

Which half reaction correctly describes the oxidation that is taking place?

Zn(s) ------ Zn2+(aq) + 2e- mc009-3.jpg

Which is an important step in the alternate method for balancing equations in redox reactions?

determining the half reactions of chemical equations

Which equation describes a reduction?

2Cl + 2e- ----- 2Cl- mc010-2.jpg

Which statement is true of the following reaction?

H2 + O2 ------- 2H+ + O2-

mc011-1.jpg

It is not balanced for charge or for number of atoms.

Consider the reaction below.

2I-(aq) + Cl2(g) ------- 2Cl-

(aq) +I2(aq) mc005-1.jpg

Which half reaction correctly describes the reduction that is taking place?

Cl2(g) + 2e- ------- 2Cl-(aq) mc005-2.jpg

Consider the reaction below.

Zn(s) + Cu2+(aq) ------ Zn2+(aq) + Cu(s) mc006-1.jpg

Which half reaction correctly describes the oxidation that is taking place?

Zn(s) ------ Zn2+(aq) + 2e- mc006-3.jpg

Consider the half reaction below.

Fe -------- Fe2+ + 2e- mc003-1.jpg

Which statement best describes what is taking place in this half reaction?

Iron is being oxidized.

Which best describes the reducing agent in the reaction below?

Cl2(aq) + 2Br-(aq) ------- 2Cl-(aq) + Br2(aq)

Bromine (Br) loses an electron, so it is the reducing agent.

Given that Cu + 2HCI ------- Cu2+ + 2CI- + H2(g) has an overall reduction potential of -0.34 V, what is a valid prediction about how this reaction works?

The reaction is not spontaneous and will require energy to proceed.

Which substance loses electrons in a chemical reaction?

the one that is oxidized, which is the reducing agent

Which of the following substances is the most powerful oxidizing agent?

CI2

The following equations are half reactions and reduction potentials.

Ag+ (aq) + e- -------- Ag(s) has a reduction potential of +0.80 V.

Cr3+ (aq) + 3e- --------- Cr(s) has a reduction potential of -0.74 V.

Which statement best compares the substances in these half reactions?

A silver ion gains electrons more easily and is a stronger oxidizing agent than a chromium(III) ion.

What is the final, balanced equation that is formed by combining these two half reactions?

Cu ------- Cu2+ + 2e-

NO-3 + 2e- +2H+ -------- NO-2 + H2O mc017-1.jpg

Cu + NO-3 + 2H+ ------ Cu2+ +NO-2 + H2O

mc017-3.jpg

Consider the reaction that occurs when copper is added to nitric acid.

Cu(s) + 4HNO3(aq) -------- (CuNo3)2(aq) + 2NO2(g) + 2H2O(l) mc024-1.jpg

What is the reducing agent in this reaction?

Cu

Which of the following is a simple definition of reduction?

the gain of electrons

Which best describes an oxidizing agent?

a reactant that undergoes reduction

Equations can be balanced by using the half-reaction method. Which step should be completed first when using this method?

finding the oxidation states of atoms

The reaction below was carried out in an acidic solution.

I- + IO-3 ------ I2 mc014-1.jpg

Which statement is true about this equation?

Although it is unbalanced, it can be balanced by using the half-reaction method.

The following equations are half reactions and reduction potentials.

Li+ (aq) + e- ---------- Li(s) has a reduction potential of -3.04 V

F2(g) + 2e- --------- 2F-(aq) has a reduction potential of +2.87 V

Now consider lithium (LI+) and fluoride (F2) as oxidizing agents. How do these compare as oxidizing agents?

Fluoride is a stronger oxidizing agent than lithium.

What is the oxidation number for N in the compound NH3? (Recall that H usually has an oxidation number of +1.)

-3

Consider the reaction below.

2Kr + Br2 ------- 2K+ + 2Br- mc004-1.jpg

What is being reduced?

only Br2

Which rule for assigning oxidation numbers is correct?

Oxygen is usually -2.

Consider the half reactions below for a chemical reaction.

Zn--->Zn2+(aq)+2e-

Cu2+(aq)+2e---->Cu(s) mc020-1.jpg

What is the overall equation for this chemical reaction?

Zn(s)+Cu2+(aq)--->Zn2+(aq)+Cu(s)

Which of the following is not an oxidation-reduction reaction?

A precipitation reaction

What must be true of a disproportionate substance?

It has an oxidation number of 0.

Which of the following is true about a redox reaction?

In a redox reaction, an electron is lost by the reducing agent.

What is the oxidation number for S in the compound SO3? (Recall that O has an oxidation number of -2.)

0

Disproportionation is a process in which a substance

is both an oxidizing and a reducing agent.

Which answer best describes what is happening in the following reaction?

2C8H18 + 25O2 --------- 16CO2 + 18H2O

This is a redox reaction in which octane (C8H18) is oxidized.

What is the reducing agent in the following reaction?

Cl2(aq) + 2Br-(aq) -------- 2Cl-(aq) + Br2(aq)

Br-

Consider the following reaction.

CO2(g) + H2(g) ------- CO(g) + H2O(l) mc025-1.jpg

What is being oxidized?

hydrogen

The information below describes a redox reaction.

Ag+(aq)+Al(s)--->Ag(s)+Al3+(aq)

Ag+(aq)+e---->Ag(s)

Al(s)-->Al3+(aq)+3e-

What is the coefficient of silver in the final, balanced equation for this reaction?

3

Which type of reaction occurs in the following equation?

mc017-1.jpg

a synthetic redox reaction

What is the overall reduction potential for the reaction Ag+(aq) + Cu(s) -------- Ag(s) + Cu2+ (aq) mc024-35.jpg

+0.46 V

Which answer best describes what is happening in the following redox reaction?

4Fe + 3O2 --------- 2Fe2O3

Iron is oxidized to form rust.