Abstract:Enthalpy of soluti on measureme nt s of four potassium salts in H20 were made in either an adiabatic or an iso pe ribol cal orimeter or both . The following summari zes the measured and recomme nd ed values: The value for KIO. has bee n corrected for the hydrol ys is of the pe ri odate ion. The .:lC " = -(82. 5 ± 4.3)J · mol -I ·K-1 for the unh ydrolysed reaction. For the reaction of KBr in H20 , .:l C " was measured as -(1 66.6 ± 7.2) ]-,nol -I·K -I in the temperature range 298 K to 3 19 K.Measure ments with … Show more
“…Gunn [4] s howed differences of as much as 35 J.mor l (0 .2%) in M ,o)n of samples with different ori gin s and drying procedures. A recent stud y [5] revea led systemati c errors of as much as 0. 7 perce nt in th e enthalp y of solution of KBr measured by three high-precision ca lori meters.…”
“…Gunn [4] s howed differences of as much as 35 J.mor l (0 .2%) in M ,o)n of samples with different ori gin s and drying procedures. A recent stud y [5] revea led systemati c errors of as much as 0. 7 perce nt in th e enthalp y of solution of KBr measured by three high-precision ca lori meters.…”
“…In our earlier study on KBr [5] the isoperibol results of Efimov showed a puzzling curvature in the plot of the values for the enthalpy of solution of KBr versus concentration of the final solutions. It now appears that this was due to a comb ination of errors from thermal lags and inadequate stirring.…”
Section: Recommended Procedures For Calorimeters Requiringmentioning
confidence: 99%
“…The vessel temperature was constantly rising throughout the experiment, and the mean temperature of the initial and final calibration periods differed from that of the reaction period by about 0.1 K or less (one exception was 0.3 K). The observed temperature 5 The results in section 4 indicate a sys temati c error estimated to be 0.06 percent du e to failure to me asure the e nergy equi va le nts over th e sam e tempe rature range as th e reacti o n. This would in crease th e mean valu e by 0.01 kj .mo!-I which would still he within th e experimental un ce rtaint y of th e valu e obtained from meas urements in th e adiabatic calorimete r.…”
Section: Addition Of Electrical Energy During Endothermic Reactionsmentioning
confidence: 99%
“…However, in some laboratories [5,14], the jacket is maintained slightly below the final temperature of endothermic reactions (where electrical energy is not added). This was done to reduce the magnitude of the heat leak corrections, and the errors in such corrections.…”
Section: Relative Jacket Temperaturementioning
confidence: 99%
“…Design criteria and possible sources of systematic errors in calorimeters have recently been discussed a priori in a series of papers by West, Churney, and Armstrong [1][2][3][4].1 They also suggest experimental tests to determine whether some systematic errors are likely to occur during calorimetric measurements. Recent work [5] indicated disagreement in results obtained by three calorimeters believed to be capable of measurements of highest accuracy and experimental imprecision of 0_1 percent or less. Two of these were isoperibol calorimeters of the same design used by different scienti sts at different locations; the values measured for the -Ce nt er for Thermodynamics and Molecu lar Science, Na ti onal Measurement Laboralory.…”
Syste mati c erro rs in an isope ribol calorimete r of a wid e ly.used design, amou nting to a bout 0.5 pe rce nt of the e nd othermi c enthalpy of solu tion of S RM 1 655 (KCI) in H20 , were fou nd to be th e res ult of e rro rs in hea t leak co rrections due to in adeq uate s tirring and comm onl y used calo rimetric procedures.Other systematic e rrors we re found in meas urements of the enthalpy of soluti o n of the exothermic reaction of tri s(hydroxymethyl)aminomethan e in aq ueou s HCI so lution.Recom mended procedures are summarized.Key words: Calorime try; enth alpy of so luti on; KCI ; so luti on calo rim etry; standard re ference materials; the rmochemistry; tris(h ydroxymeth yl)amin omethane.
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