Updated Nov.17/04	

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NUMERICAL ANSWERS TO ASSIGNED TUTORIAL PROBLEM SETS FOR CHEM206
FROM KOTZ & TREICHEL'S CHEMISTRY & CHEMICAL REACTIVITY			
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NOTE:  not all answers have been verified.  SO FAR: checked up to Ch.19 #29
NOTE:  "^" means "raised to the power of..." to indicate scientific notation

Ch.	Q#	Ans.		Units		SFs	Comments
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19	13a						impure Si
19	13b						O2(g) at 0C
19	13c						iodine gas
19	13d						at lower P
19	19	-99.1		J/K		3	
19	23	-15.4		J/K		3	
19	27	318.9		J/K		4	delta-S universe > 0 --> spontaneous
19	29						spontaneous at all temperatures
19	29						favoured at high temperatures
19	33a	-431.16		kJ		5	delta-H
19	33a	-125.3		J/K		4	delta-S  
19	33a	-393.8		kJ		5	delta-G <0;product favoured (fwd rxn is spontaneous); enthalpy-driven

19	33b	49.03		kJ		4	delta-H
19	33b	-252.4		J/K		4	delta-S  
19	33b	124.3		kJ		4	delta-G >0;reverse is spontaneous; driven in reverse by both H & S

19	37a	-249.5		kJ		4	product-favoured
19	37b	-990.32		kJ		5	product-favoured
19	41a	100.89		J/K		5	entropy-favoured;higher T --> more products

19	41b	-187.95		J/K		5	entropy-disfavoured;higher T --> more reactants…

19	41c	315.5		J/K		4	entropy-favoured;higher T --> more products

		note:  SiCl4 is (g), not (l)
					
19	41d	15.7		J/K		3	entropy-favoured; higher T --> more products

19	43	2141		K		4	this T or higher is necessary

19	45	2.5x10^-29			2	this is Kp  --> << 1, means reactants dominate at eqm
							large +ve delta-G (non-spontaneous fwd; spont. reverse!)

19	47	4.0x10^14			2	large Kp value --> products dominate at eqm
							matches large -ve delta-G (spontaneous fwd rxn)

19	49	-125.52		kJ		5	delta-H
19	49	-129.9		J/K		4	delta-S
19	49	-86.81		kJ		4	delta-G --> negative; product-favoured under std. conditions

19	51	-352.88		kJ		5	delta-H
19	51	21.31		J/K		4	delta-S(sys)
19	51	1205		J/K		4	delta-S(univ) --> positive, spontaneous fwd.

19	53a	117		kJ/mol		3	delta-G (std states)...determined using delta-G=(delta-H)-Tx(delta-S)
							calculated via...delta-S(sys)=216.53 J/K; delta-H=181.66 kJ
							delta-S(surr)=-609.6 J/K from delta-H.  delta-S(univ)=-393.1 J/K

	53b	3.1x10^-21			2	Kp is very small, therefore reactant favoured

19	55a	2.8		kJ		2	delta-G --> positive;rxn does not occur on its own…

19	55b						high T,P used to overcome unfavourable thermodynamics

19	69a						+ + +
19	69b						-  +  - 
19	69c						 -  +  -

19	73	6.98		kJ/mol		3	delta-G(rxn) at std states calculated via -RTlnK

19	77a	91.42		kJ		4	delta-G(rxn, std) calculated from thermo. data
	77b	9.5x10^-17			2	eqm constant K; for 298K using delta-G=-RTlnK
	77c	707.3		degrees C	4	temp where delta-G=0 (eqm for std state concentrations)

19	79a	161.61		J/K		5	delta-S > 0 matches liquid --> gases
19	79b	115.3		kJ		4	delta-G > 0 therefore non-spont. (ie, reverse rxn is spont.)

19	79c	739		C		3	lowest T at which fwd rxn is spontaneous

19	87a						O2 = oxidizing agent; N2H4 = reducing agent 

19	87b	-623.77		kJ		5	delta-G < 0 therefore spontaneous

19	89	-10.9		kJ/mol		3	delta-G(std) calcd for 623K using Kp=8.16 & -RTlnK...