If delta H degree = -259.7kJ/mol and delta s degree = +7.8 J/K, what is the delt

Question

If delta H degree = -259.7kJ/mol and delta s degree = +7.8 J/K, what is the delta s_total for this reaction. Is the reaction spontaneous under standard-state conditions at 25degreeC? Estimate at what temperature, if any, the reaction will become non spontaneous. What is the cell potential at 25degreeC for the following galvanic cell? Pb(s)|PB^2+ (1M)||Cu^2+ (1 times 10^-4M)| Cu(s) If the Pb^2+ ion concentration is maintained at 1.0 M, what is the Cu^2+ concentration when the cell potential to drop zero? How many grams of silver will be obtained when the aqueous silver nitrate solution is electrolyzed for 20 minutes with a constant current of 2.40A? What is the systematic name of each of the following coordination compounds? a) [Co(NH_3)_4Br_2]Br b) [V[H_2O)_6](NO_3)_3 c) [FeCl_4] Identify the oxidation state of the metal in each of the following compound: a) [Ag(NH_3)_2NO_3 b) Cs[CuCl_2] c) Co(NH_3)_3NO_2)_3 Balanced the following equations for the nuclear fission of U-235:^235U right arrow^160Sm +^72Zn + ?^1n^235U right arrow^87Br + ? + 2^1n Calculate the Binding energy in MeV/nucleon for Ni-58 nucleus (mass = 57.93535 amu) (Mass of a proton: 1.00728 amu, Mass of a neutron: 1.00866 amu and Mass of electron; 0.0005486 amu) Write condensed structures for each of the following compound. a) 2, 2, 3-Trimethylpentane b) 3-ethylhexane c) 5-isopropyl-2-methyl octane Propose structures and draw condensed formulas of three isomers of C_3H_8O

Explanation / Answer

12) Reduction of mercury(II) oxide with zinc gives metallic mercury

            HgO(s) + Zn(s) à ZnO(s) + Hg(l)

Tsurr = 0 oC = 273 K (Standard temperature)

S_surr = -H/Tsurr = - (-259700J/mol)/273K

S_surr = +948.71 J/K

S_total = +948.71 J/K - 7.8 J/K
S_total = 940.91 J/K

13) Cell potential at 25oC for following galvanic cell

Pb (s) | Pb2+ (aq) (1.0 M) || Cu2+ (aq) (1 × 10-4 M) | Cu (s)

Anode Pb (s)

Cathode Cu(s)

Reduced Cu2+

Oxidized Pb(s)

Anode Pb(s) -> Pb2+ + 2e-

Cathode Cu2+ + 2e- --> Cu(s)

Overall Reaction Pb(s) + Cu2+ --> Pb2+ + Cu(s)

Standard Reduction Potentials for each half reaction

Eanode = 0.1263 volt

Ecathode= 0.3402 volt

Estdcell = Ecathode Eanode

Estdcell = 0.3402-(-0.1263) = 0.4665V

Ecell = Estdcell – (RT/nF)×ln(CPb/CCu)

Ecell = 0.4665 – (8.314 JK1mole1 × 298.15 / 2 × 9.649 × 104 Cmole-1 ) × ln(1/0.0001)

Ecell = 0.4665 –( 0.01284 × 9.210)

Ecell = +0.348 V

14) From the first law of electrolysis we know that, The amount of a given product liberated at an electrode during electrolysis is directly proportional to the quantity of electricity which passes through the electrolyte solution

So,       m Q

And     Q = I × t

where I is the strength of current in amperes and t is the time in second for which the current has been passed,

Therefore, m I × t or m = Z × I × t

An ampere is a coulomb per second. So, First we have to convert the 20 minutes to seconds and multiply by 2.32 A. Since, there are 95,600 coulombs for one mole. So convert the coulombs above to moles and multiply by the mol mass of silver for your answer

Q = I × t = 2.32 × 20 × 60 = 2784 coulombs

95600 coulombs = 1 mol of silver

So, 2784 coulombs = 2784/95600 = 0.02912 moles

Weight of silver deposited = moles × molar mass of silver

= 0.02912 × 104.86 = 3.14 g

15) Systemic name of following coordinate compounds

[Co(NH3)4Br2]Br = tetraaminedibromocobalt(II)bromide

[V(H2O)6](NO3)3 =Hexaaquavanidium(III)nitrate

Cs[FeCl4] = Caesiumtetrachloroferrate(III)

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