Electrochemistry Questions and Answers

Consider the voltaic cell illustrated in the figure Figure 1 which is based on the cell reaction Zn s Cu aq Zn aq Cu s Figure Zn anode Switch NO Zn NO NO 10 Voltmeter Na NO NO 1 of 1 Cu Cu cathode Part A Under standard conditions what is the maximum electrical work in joules that the cell can accomplish if 45 0 g of copper is plated out Wmax Submit Provide Feedback VAEO Request Answer 197 J Next

Mg s Fe2 aq Mg2 aq Fe s The galvanic cell described above has a standard cell potential of 1 93 V The standard reduction potential of Mg2 corresponding to the half reaction Mg2 aq 2e Mg s is 2 37 V Calculate the standard reduction potential of iron II

2 points Use Molecular Orbital diagram to determine the diatomic molecule of O 2 is paramagnetic or diamagnetic Paramagnetic Diamagnetic

Current Attempt in Progress Calculate AG for the reaction 2MnO4 6H 5HCHO2 2Mn 8H O 5CO2 for which E cell 1 69 V AG i kJ

A voltaic cell is constructed that is based on the following reaction Sn aq Pb s Sn s Pb aq Part A If the concentration of Sn in the cathode compartment is 1 20 M and the cell generates an emf of 0 17 V what is the concentration of Pb in the anode compartment Express your answer using two significant figures Pb Submit VAXO Part B Previous Answers Request Answer X Incorrect Try Again 19 attempts remaining VAX If the anode compartment contains SO 1 40 M in equilibrium with PbSO4 s what is the K of PbSO Express your answer using two significant figures M

oltaic cell consists of a strip of cadmium metal in olution of Cd NO3 2 in one beaker and in the er beaker a platinum electrode is immersed in a Cl solution with Cl2 gas bubbled around the ctrode A salt bridge connects the two beakers Part C Write the equation for the overall cell reaction Express your answer as a chemical equation Identify all of the phases in your answer Submit A O Part D A chemical reaction does not occur for this question pa Request Answer What is the emf generated by the cell under standard conditions Express your answer using four significant figures

Write a CER Abstract paragraph that answers the question What is the formula for the iron containing compound formed when copper II sulfate reacts with pure iron Be sure to include a clear claim that directly answers the question specific numerical data as well as a brief description of how you obtained that data as evidence and a logical reasoning that clearly explains why the evidence proves your claim Since this lab includes a mathematical process for determining the answer your reasoning should include a step by step explanation of this process Complete sentences and paragraph format are required

For the reaction 2Cr2 aq Cl g 2Cr3 aq 2Cl aq the value of E cell is 1 66 volt What is the value of E cell in volt for the following reaction Cr aq Cl aq Cr2 aq Cl g Report your answer with 2 places past the decimal point Do not put unit in your answer Type your answer

mental calcium is produced by the electrolysis of ten CaCl Part A What mass of calcium can be produced by this process if a current of 8300 A is applied for 53 h Assume that the electrolytic cell is 55 efficient Express your answer using two significant figures m 1 8x105 g Ca Submit Previous Answers Correct Part B What is the minimum voltage needed to cause the electrolysis Express your answer using three significant figures VAE

In a galvanic cell a spontaneous redox reaction occurs However the reactants are separated such that the transfer of electrons is forced to occur across a wire The resulting cell potential is measured in volts V and is defined by the equation given below E cell E red cathode E red anode A table of standard reduction potentials gives E values for common half reactions red Reduction half reaction E V 0 80 0 34 Ag aq eAg s Cu aq 2e Cu s Ni2 aq 2e Ni s Fe aq 2e Fe s Zn aq 2e Zn s 0 26 0 45 0 76 Part A Calculate the standard potential for the following galvanic cell which has the overall balanced equation Zn s Cu aq Zn aq Cu s Express your answer to three significant figures and include the appropriate units View Available Hint s E cell D S Zn s Zn aq Cu aq Cu s Templates Value Units

Which of the following equations represents the Nernst equation E E log F RT nF O b E E RTlog Q Oc O d E E RT nF O e nF RT E E RT In2

Balance the following redox reaction in basic solution 2 Cr OH 3 s Cu aq Cro aq Cu aq 4 Cr OH s Cu aq Cro aq Cu aq VE SEKSAAN PEN P ANDER GERU MIS S SE Se p Pes SALEINST

Through electrolysis a student collects 13 0 g of hydrogen gas and 103 0 g of oxygen gas The reaction was allowed to proceed to completion What was the mass of water initially present Round your answer to the nearest tenth Provide your answer below

Find the reduction potential of Ag electrode which is present in saturated solution of AgCl having conductivit 3 4 x 10 6 ohm cm and that of H O l used is 2 02 x 10 6 ohm 1cm for AgCl is 138 ohm cm mol EAg Ag 0 80 V O 1 059 V 0 505 V 0 0 505 V

A potentiometric titration is one in which the Nernst equation is E E 0 059 pH the CI is constant the end point is found by measuring the potential of an electrode dipped into the reaction vessel the potential is plotted vs concentration

Cu s Ag aq Cu s Cu aq Ag s 1 Which substance gets oxidized Balance the redox reaction 0 redox reaction Ag aq Cu s Ag s Cu aq Cu aq Cu s Ag s Cu aq 0 Which substance gets reduced O Ag aq 2

A galvanic cell is constructed with a copper electrode dipping into a 0 012 M solution of Cu ions and a magnesium electrode immersed in a solution with an unknown concentration of magnesium ions The cell potential is measured as 2 85 volts at 25 C What is the concentration of magnesium ions Note round your answer to 2 significant digits F 9 65 x 104 C mol e Mg s Cu aq Mg aq Cu s Mg2 M

The E cell 0 135 V for the reaction 312 s 5Cr O7 aq 34H aq 6103 aq 10Cr aq 17H O What is Ecell if Cr O72 0 022 M H 0 22 M 103 0 00020 M and Cr 0 0018 M Ecell no goj V

sider these reactions ction 1 H g Cl2 g 2HCl g ction 2 20F g O2 g 2 F g ction 3 N g 202 9 2NO2 9 plete the table for Reaction 3 Assume the process occurs near room temperature Change in Gibbs Fre Energy Change in Enthalpy elect AH 184 6 kJ AH 49 4 kJ AH 66 4 kJ Change in Entropy Select Select

Separate this redox reaction into its balanced component half reactions Use the symbol e for an electron Cl 2K 2 KCI oxidation half reaction 16

Determine the value of Ke at 25 C for the reaction 2H O 2Cl 4H 4CI O2 E Volts 1 36 1 23 Half Cell Reaction Cl g 2e 2Cl aq O g 4H aq 4e2H O Enter your response in scientific notation e g enter 2E3 for 2000

Write a balanced half reaction for the oxidation of manganese ion Mn to solid manganese dioxide MnO in acidic aqueous solution Be sure to add physical state symbols where appropriate

anode and the one on the right is the cathode Anode half reaction L 2CF Cathode half reaction 2c C Shorthand notation 2 Ag s 1 Pb s Pb PbCl s 2c 2 CI Answer Bank CT aq 2 AgCl s 10 I Ag s AgCl s V Ag

Based on the information given classify each of the pure substances as Classification is possible because of insufficient information Analysis with an elaborate instrument indicates that substance A contains two elements substance B and substance C react to give a new substance D substance E decomposes upon heating to give substance F and substance G heating substance H to 1000 C causes no change substance I cannot be broken down into simpler substances by chemical means substance J cannot be broken down into simpler substances by physical means heating substance K to 500 C causes it to change from a solid to a liquid Element Compound Cannot be classified

2 points When AH is positive and AS is positive O O AG will be negative at high temperatures AG will always be positive at all temperatures AG will be negative at low temperatures AG will always be negative at all temperatures

Consider the following phase change equilibrium CHCl3 s CHC13 1 If AHO is 9 14 kJ mol and AS is 41 26 J mol K determine the melting point of CHCl3 in K Do not report units in your answer Report you answer as a whole number no places past the decimal point Type your answer

Out of A B and C which solution is the strongest electrolyte OA OB B OC All of them are strong electrolytes

Problem 6 Consider the galvanic cell based on the following hal 2 Fe aq 2e Fe s 2 Zn aq 2e Zn s a Determine the overall cell reaction Write the cell notation for a voltaic cell b Determine the overall cell reaction and E cell at 25 C

A common experiment to determine the relative reactivity of metallic elements is to place a pure sample of one metallic element into an aqueous solution of a compound of another metallic element If the pure metal you are adding is more reactive than the metallic element in the compound then the pure metal will replace the metallic element in the compound For example if you place a piece of pure chromium metal into a solution of copper II sulfate chromium will slowly dissolve to produce chromium III sulfate solution and the copper II ion of the copper II sulfate will be converted to metallic copper Choose the unbalanced equation for this process Cu s Cr SO4 3 aq CuSO4 aq Cr s Cr s CuSO4 aq Cr SO4 3 aq Cu s

The acid ionization equilibrium constant Ka describes the reaction where HA is a generic weak acid OH O AHA H O OHA H A H A HA HA H O H O A O HA H O H A H O HA OHH O A

An electrolytic cell is used to produce aluminum metal from a eutectic blend of aluminum oxide and the mineral cryolite. The relevant cathodic half reaction is as follows. Al³+ + 3 e Al How many grams of aluminum metal are produced if a constant current of 17.6 amps is passed for 67 minutes and 39 seconds, assuming a 100% Faradaic efficiency for aluminum production? Please report your answer with 3 significant figures.

An electrolytic cell is prepared for the purpose of producing chlorine gas, Cl₂ (g), from molten magnesium chloride, MgCl2 (1). Consider the half reactions listed below. During operation, chlorine gas will be produced at the. Mg2+ + 2e → Mg Eº = -2.356 V vs SHE Cl₂ + 2e → 2C1- Eº = +1.358 V vs SHE Select one: O a. salt bridge O b. anode O c. more than one of these O d. negative terminal O e. cathode

Suppose that an acid flux is inadvertently left on the surface of a silver contact and that in the presence of a thin film of condensed moisture, the acid residue has a pH of 5.0. Under what range of electrode potentials could the corrosion of silver occur in the thin-film electrolyte?

KCI (100mM) was entrapped inside large unilamellar vesicles. Can a diffusion potential across the bilayer be generated by diluting with buffer containing 100mM KCI and a K+ specific ionophore? Explain why or why not.

Which 0.10 M solution best conducts electricity? ammonia (NH3) ethyl alcohol (C₂H5OH) sucrose (C₁₂H22011) potassium bromide (KBr)

The acid ionization equilibrium constant, Ka, describes the reaction (where HA is a generic weak acid): H3O+A- <--> HA+H₂O HA+H₂A+ <--> H₂A++ HA HA+ H₂O <--> H3O++A- HA+H3O+ <--> H₂A++ H₂O HA+OH- <--> H₂O + A-

Which of the following is the correct NET ionic equation for the above reaction? a. H+(aq) + OH(aq) → H₂O(l) b. KOH(aq) + H₂S(aq) → K₂S(aq) + H₂O(l) c. 2K+(aq) +1 S²-(aq) → 1K₂S(aq) d. 2KOH(aq) + 1H₂S(aq) → 1K₂S(aq) + 2H₂O(l)

B C D Cu 1 M Cu(NO3)2 The cell would not operate because a current could not be conducted between the half-cells. +0.46 V To construct the galvanic cell illustrated above, the salt bridge was prepared by soaking a piece of cotton in 5.0 M NaNO3(aq) before placing it inside the U-shaped tube filled with distilled water. If the cotton was soaked in distilled water by mistake, which of the following best explains how the operation of the cell would be affected? The operation of the cell is not affected because neither Na+ (aq) nor NO3(aq) is involved in the redox reaction that takes place. The cell will operate for a much longer time because the flow of electrons through the circuit will eventually be reversed. Salt Bridge (NaNO3) Piece of Cotton 1 M AgNO3 The operation of the cell generates a higher potential because there are fewer ions in the solution, making the reaction more thermodynamically favored. Ag

Using molecular polarity and the symmetry of the molecules write a brief explanation of which of the two solvents you would choose to dissolve the marker ink. In your explanation, be sure to explain how molecular geometry and polarity affect your decision. Refer back to the case to see what solvents are available. They are not the same as the ones from our lab

(Mixing hot and cold water) What would be the temperature of a mixture of 100g of 20°C water and 100g of 80°C water? Write your answer in tenths. Only the numerical value will be graded.

Choose the correctly punctuated sentence below. Today is a perfect day to go swimming, the boys cheered. Yesterday Jane said, "Tomorrow I'll bring back your garden shovel" however she did not. When did Napoleon say, "Victory belongs to the most persevering"?

Choose the correct answer for the following question from the choices below. Which option contains a sentence that is punctuated correctly? O "Heather called out, Are you finished? We really should get going." Heather called out "Are you finished?" We really should get going. Heather called out, "Are you finished? We really should get going."

A galvanic cell at a temperature of 25.0 °C is powered by the following redox reaction: 2 MnO, (aq) + 16H* (aq) +5 Pb (s)-2 Mn²+ (aq) +8H₂0 (1) +5 Pb²+ (aq) Suppose the cell is prepared with 7.95 M MnO4 and 1.70 M H in one half-cell and 2.07 M Mn²+ Calculate the cell voltage under these conditions. Round your answer to 3 significant digits. and 7.43 M Pb2+ in the other.

Suppose a powerful battery is connected between a pair of inert graphite electrodes dipped into a pot of molten aluminum oxide (Al2O3) (see sketch at right). The battery makes a current of electrons flow in the directions shown by the arrows in the sketch. Note: Group 14 and Group 24 metals all melt at temperatures lower than their salts. Which electrode is the cathode? Write a balanced equation for the half-reaction that takes place at electrode A. Write a balanced equation for the overall reaction. A OB 0 0 0-0 la X G ? A H 7e- B

In the industrial "chlor-alkali" process, pure chlorine and sodium hydroxide are produced by electrolyzing brine, essentially an aqueous solution of sodium chloride. Suppose a current of 29.0 A is passed through an aqueous solution of NaCl for 48.0 seconds. Calculate the mass of pure chlorine produced. Round your answer to 3 significant digits. Also, be sure your answer contains unit symbol. 0 D.O X F Gala 5 ?

Purification of nickel can be achieved by electrorefining nickel from an impure nickel anode onto a pure nickel cathode in an electrolytic cell. How many hours will it take to plate 14.0 kg of nickel onto the cathode if the current passed through the cell is held constant at 38.0 A? Assume the nickel in the electrolytic solution is present as Ni²+.

11. Describe each of the following as acidic, basic, or neutral. Blood plasma Lemon juice H₂O NaCl in H₂0 Coffee Milk of Magnesia

What essential parts are needed to make a battery? fuse reducing agent porous barrier or salt bridge cell acid voltage regulator oxidizing agent

Suppose 0.620 mol of electrons must be transported from one side of an electrochemical cell to another in 82. seconds. Calculate the size of electric current that must flow. Be sure your answer has the correct unit symbol and round your answer to 2 significant digits. 0 0.0 X μ 00 Ś 0² ?

When a lead acid car battery is recharged by the alternator, it acts essentially as an electrolytic cell in which solid lead(11) sulfate (PbSO4) is reduced to lead at the cathode and oxidized to solid lead(II) oxide (PbO) at the anode. Suppose a current of 37.0 A is fed into a car battery for 20.0 seconds. Calculate the mass of lead deposited on the cathode of the battery. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.