Question 1

In the redox reaction $$\mathrm{H_2S + $$HNO_3$$ \rightarrow S + NO} ($$acidic solution), what is the correct coefficient for sulfur ($$\mathrm{S}) $$when the equation is balanced with the smallest whole-number coefficients?

Accepted Answer

3

Question 2

Given the cell notation $$\mathrm{Pt(s) | H_2$(g) | H^+(aq) || Ag^+(aq) | Ag(s)}$$, what is the balanced overall cell reaction?

Accepted Answer

$$\mathrm{H_2$(g) + 2Ag^+(aq) \rightarrow 2H^+(aq) + 2Ag(s)}$$

Question 3

An electrochemical cell is constructed with a Fe electrode in $$1.0\ \mathrm{M\ $$FeCl_2$$}$$ and a Sn electrode in $$1.0\ \mathrm{M\ Sn(NO_3$)_2}$$, connected by a KCl salt bridge. When the cell operates spontaneously, which statement is completely true?

Accepted Answer

The tin electrode gains mass and the tin electrode is the cathode.

Question 4

For the cell reaction $$\mathrm{Zn + HgO \rightarrow ZnO + Hg}$$, which half-reaction occurs at the anode?

Accepted Answer

$$\mathrm{Zn \rightarrow Zn$$^{2+}$$ + 2e^-}$$

Question 5

Calculate $$E^\circ_{cell}$$ for the reaction $$\mathrm{2Fe$$^{2+}$$(aq) + Cd$$^{2+}$$(aq) \rightarrow 2Fe$$^{3+}$$(aq) + Cd(s)}. $$Which value is correct?

Accepted Answer

$$-1.17\ \mathrm{V}$$

Question 6

According to the cell diagram $$\mathrm{Sn | Sn$$^{2+}$$ || NO_3$^-\ (acid\ soln), NO(g) | Pt}$$, which species undergoes reduction?

Accepted Answer

NO$$_3^-$$

Question 7

Which of the following reactions will occur spontaneously at standard-state conditions and $$25^\circ\mathrm{C}$$?

Accepted Answer

$$\mathrm{Mg$$^{2+}$$ + Ca \rightarrow Mg + Ca$$^{2+}$$}$$

Question 8

Using a table of standard electrode potentials, which statement is completely true?

Accepted Answer

H$$^+$$ can oxidize Fe, and Ni can reduce Br$$_2.$$

Question 9

For the electrochemical cell $$\mathrm{Ni(s) | Ni$$^{2+}$$(1\ M) || H^+(1\ M) | H_2$(1\ atm) | Pt(s)}$$, which change will decrease the cell voltage?

Accepted Answer

Increase the pressure of H$$_2 to$$ $$2.0\ \mathrm{atm}.$$

Question 10

Magnesium reacts with dilute hydrochloric acid. Which equation correctly represents this reaction?

Accepted Answer

$$\mathrm{Mg + 2HCl \rightarrow H_2$ + $$MgCl_2$$}$$

Question 11

How many coulombs of electrical charge are required to reduce $$0.44\ \mathrm{mol} Ca$^{2+}$$ ions to calcium metal?

Accepted Answer

85,000 C

Question 12

How long will it take to produce $$78.0\ \mathrm{g} of Al $$metal by the reduction of Al$$^{3+} in an $$electrolytic cell with a current of $$2.00\ \mathrm{A}$$?

Accepted Answer

116 h

Question 13

The reduction of $$1.00$$ mole of Cr$$^{3+} to Cr $$requires $$9.65 	imes 10^4$ C of electrical charge. Is this statement true or false?

Accepted Answer

False

Question 14

A patient receives an intravenous solution containing Ag$$^+$$ ions. If a redox reaction occurs in the bloodstream, which species could reduce Ag$$^+ to Ag(s$$)?

Accepted Answer

H$$_2$$

Question 15

A battery uses the reaction $$\mathrm{Zn + Cu$$^{2+}$$ \rightarrow Zn$$^{2+}$$ + Cu}. If $$the battery is discharged, which electrode is the anode?

Accepted Answer

Zinc electrode

Question 16

In an electrolytic cell, $$\mathrm{Al$$^{3+}$$} is $$reduced to Al metal. If $$1.00\ \mathrm{mol} of $$electrons are passed, how many grams of Al are produced? ($$\mathrm{M_{Al} = 27.0\ g/mol})$$

Accepted Answer

9.00 g

Question 17

A student wants to plate $$0.50\ \mathrm{mol} of $$silver onto a necklace using Ag$$^+$$ ions. How many coulombs are required? ($$\mathrm{Ag^+ + e^- \rightarrow Ag})$$

Accepted Answer

48,250 C

Question 18

A car battery is rated at $$60\ \mathrm{Ah} ($$ampere-hours). How many moles of electrons does this correspond to?

Accepted Answer

$$13.5\ \mathrm{mol}$$

Question 19

A metal is oxidized in an electrochemical cell. Which of the following best describes the process at the anode?

Accepted Answer

Electrons are lost by the metal.

Electrochemistry and Redox Reactions Study Guide

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