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Clarification for Atkins' problems

Updates: Dec. 12, 2006

Please email me if you have any corrections you would like to add.

7th edition errata (from the W.H. Freeman website)
8th edition errata (from the W.H. Freeman website)

Ex. 2.10a, 8th Ed. (2.13a, 6th Ed; 2.16a, 7th Ed).
  The sign of the w calculated in this problem is incorrect: you should get -194 J for this process.  It is correct in the 8th edition, wrong in previous editions.

Ex. 2.15a (2.25 7th Ed.) In the 7th edition, the answer is correct, but in 2.15a of the instructors manual (8th edition), the Vf is incorrectly calculated.  The final answers should be Vf = 9.44 10-3 m3, Tf = 288 K and w = -0.46 kJ.

Ex. 3.14 (7th), Prob. 2.24 (8th). There is a typo in the question.  In the denominator of the expression you are being asked to show, it should be (dV/dP)T, not (dV/dT)T (the latter does not make any sense.

P3.26 (8th edition).  The wording of this question is awkward, as Atkins et al. have combined two separate questions from previous conditions into one.  When he says, "Use the Maxwell relations to express the derivatives (a) (dS/dV)T and (dV/dS)p .... in terms of heat capacities, a and kT...", he does not mean to use them together, but to treat each one separately.  So in other words, do the one for (dS/dV)T and then the one for (dV/dS)p - they have nothing to do with one another other than being in the same sentence.

P4.5 (7th edition), P3.5 (8th edition). In the 8th edition, Atkins asks for a DG associated with the Carnot cycle, for individual steps, as well as the total.  Unfortunately, they miscalculate step 3, where DG should be equal to half of that in step 1 (i.e., -5.75 kJ mol-1).  The DGtot for the cycle should be equal to zero, but you cannot calculate the DG for steps 2 and 4 directly, since you do not know that value of S (i.e., DG = DH - SDT).  However, since you know that DGtot is zero, you can indirectly calculate DG for these steps 2 and 4, and for both steps, it is DG = +8.625 kJ.  Click here for a quick diagram on this question.

Ex. 4.8 (6th); Ex. 4.11 (7th); Ex. M3.3 (8th).  This question is sort of asked in a tricky/unfair way, because if you look at the solution manual, you will see that the heat capacity has a temperature dependence (i.e., Cp is a function of temperature, defined as Cp,m = a + bT.  If you are asked such a question on an examination, the temperature dependence of the Cp,m will be mentioned, otherwise, you are to assumed that the Cp,m is constant over the temperature range specified.  Otherwise, the question is ok!  Also note, that the coefficient "b" should be in units of K-1, and some of the tables in the book list the units as K, which is incorrect.

Ex. 6.7 (6th); Ex. 4.4 (8th).  Click here for a clarification of how this problem is done.

Ex. 6.8b (7th); Ex. 4.5b (8th).  The "certain liquid" that freezes is ethanol.  The molar mass is needed to complete this problem, and in the solutions manual, they just pull the mass out of thin air.  In the 6th edition, this question actually said "ethanol", so work with this as your liquid.

Ex. 6.10a (7th); Ex. 4.7a (8th).  Students with the 8th edition do not have this solution - it is actually quite simple, but seems a bit out of place for this chapter.  Still a good question.  Click here to see how to do it.

Ex. 6.13 (7th); Ex. 4.10 (8th).  Atkins does not really give enough info here to make the question very fair.  On an examination, you would be given the
DvapH for H2O to start, and probably suggested as a hint that you start from the relationship H = U + pV to get going on this problem.

Table 7.1, 7th edition.  Henry's Law constants for gases at 298 K are listed as K/(10 MPa) (which is like saying K/107 Pa).  However, these numbers are off by a factor of 102, so the table should read: Henry's Law constants for gases at 298 K are listed as K/(1 GPa) or K/(1 109 Pa).  For example of use, see Ex. 7.15a,b (7th) or 7.12a,b (6th).

Ex 8.2b (8.9b 6th):
Atkins asks for a sketch including "formation of an azeotrope at xB = 0.333," however, he does not state whether he wants a high-boiling or low-boiling azeotrope.  The possible reason for this is that this is a constant-temperature/composition diagram (i.e., a pressure/composition diagram); so an azeotrope in either direction should be fine, given the information.  ***Update: Dec. 12, 2006: Atkins asks to sketch a "constant temperature-composition liquid-vapour...diagram.." the word constant should not be is just a temperature composition diagram.

Ex. 8.7b (8.4b 6th):
Atkins states: "Benzene and toluene form nearly ideal solutions," and goes on to ask for calculation of pressure when boiling begins, etc.  However, he does not make it clear that he is talking about a 50/50 mol% mixture (i.e., xB = 0.5 and xT = 0.5); remember, an ideal solution is not necessarily 50/50, it just means that the two components mix in a completely homogeneous fashion, with regard for molecular interactions, excess state functions, etc.

Ex. 8.16a,b (8.15a,b 6th): ***update: Dec. 11, 2006
Atkins' asks you to "state the solubility" - all he means is the composition of the phases at the various points (i.e., express in terms of mole fractions).  I am not sure why he asks for solubility in particular, as his solution manual answers do not reflect this.  Also, the phase diagram in Fig. 8.36 (7th) does not match the solution manual exactly - but do not get thrown by this (they are similar enough; the same happens in the 6th edition).  Also note that the right-most phase is Ag(s) contaminated (or doped) with Sn.  ***Update: The temperature scale in Fig. 6.41 in the 8th edition is incorrect, and you cannot properly answer the question.  Click here to use Fig. 8.37 (7th edition) for this phase diagram question.

Ex. 8.17a (8.16a, 6th):
Answering part (f) literally (at 85 C) will put you right in the gas phase.  The phase diagram in the solution manual does not match that in the book.  You can try two things: try answering the question in the book at 80 C, or just make sure you understand that answer as given in the solution manual.  I am not sure why there is this pretty major difference between phase diagrams, since in the book 85 C is in the gas phase (P = 1), and in the solution manual, 85 C is in the liquid + gas phases (P = 2).

Last Updated Friday June 22, 2007
Copyright Rob Schurko, 2001-2006.