heat capacity and thermodynamic properties of cesium ...ion, which leads to the diﬀerence of the...

Research ArticleHeat Capacity and Thermodynamic Properties of CesiumPentaborate Tetrahydrate

Kangrui Sun Panpan Li Long Li Yafei Guo and Tianlong Deng

Tianjin Key Laboratory of Marine Resources and Chemistry College of Chemical Engineering and Materials ScienceTianjin University of Science and Technology Tianjin 300457 China

Correspondence should be addressed to Yafei Guo guoyafeitusteducn and Tianlong Deng tldengtusteducn

Received 24 October 2019 Revised 30 November 2019 Accepted 6 December 2019 Published 28 February 2020

Academic Editor Joatildeo Paulo Leal

Copyright copy 2020 Kangrui Sun et al 1is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

1is paper reports the molar heat capacities of β-CsB5O8middot4H2O which were measured by an accurate adiabatic calorimeter from298 to 373K with a heating rate of 01 Kmin under nitrogen atmosphere Neither phase transition nor thermal anomalies wereobserved 1e molar heat capacity against temperature was fitted to a polynomial equation of Cpm (Jmiddotmolminus 1middotKminus 1)

61807702 + 3952669[T minus (Tmax +Tmin)2](Tmax minus Tmin)2] minus 346888[(T minus (Tmax +Tmin)2)(Tmax minus Tmin)2]2 + 79441[(T minus (Tmax+Tmin)2)(Tmax minus Tmin)2]3 1e relevant thermodynamic functions of enthalpy (HT minus H29815) entropy (ST minus S29815) and Gibbs freeenergy (GT minus G29815) of cesium pentaborate tetrahydrate from 298 to 375K of 5K intervals are also obtained on the basis ofrelational expression equations between thermodynamic functions and the molar heat capacity

1 Introduction

Boron and borates are considered as a kind of modernstrategic resource worldwide for high melting point highhardness high strength light weight and abrasion resis-tance and they are extensively applied in whisker mate-rials superconducting materials fuel-rich propellants andother high-technology domains [1ndash4] Nowadays thecontinuously increasing demand for cesium borates owingto the significant physical interest [5] along with theirlimited production has led to a situation where the supplyfails to meet the market demand A number of salt lakeswith an abundance of boron resources are widely dis-tributed in the western regions of China and studies onthermodynamic properties are of great importance notonly in guiding the comprehensive utilization of the re-sources but also in evaluating and explaining the corre-sponding physicochemical properties as well as exploringnovel methods for more effective and efficient extractionfor salt lake resources Hence in order to provide usefulinformation for extracting cesium borates and synthesizing

materials it is highly desirable to study the thermodynamicproperties

1e thermodynamic properties for borates or its aqueoussolutions have attracted great attention in these past fewyears including the enthalpy of dilution [6] the molar heatcapacity [7ndash10] the apparent molar volumes [11 12] andthe standard molar enthalpies of formation [13ndash15] Heatcapacity is one of the more valuable thermophysicalquantities and reflects the ability of a substance to absorb orrelease heat without phase transition Cui et al [7] reportedthe heat capacity of lithium pentaborate pentahydrate usingan adiabatic calorimeter at the temperature from 297 to375K and relevant thermodynamic functions were obtainedat the temperature of 5 K intervals And the heat capacitiesand thermodynamic functions of the aqueous Li2B4O7 so-lution were measured at a concentration of 00187 and03492molmiddotkgminus 1 from 80 to 355K [8 9] In addition the heatcapacity of cesium tetraborate pentahydrate has beenmeasured with the high-precision TG-DSC LABSYS Evo inthe range of 303 to 349K [10] However up to now there areno data reported on the heat capacity of cesium pentaborate

HindawiJournal of ChemistryVolume 2020 Article ID 5198374 6 pageshttpsdoiorg10115520205198374

tetrahydrate In this paper the heat capacity and the relatedthermodynamic functions of enthalpy entropy and Gibbsfree energy for β-CsB5O8middot4H2O have been determined forthe first time

2 Experimental

21 Materials 1e purity degree and purification of thechemicals used in this work are tabulated in Table 1 1edoubly deionized water (DDW) produced by ULUP-II-10T(Chongqing Jiuyang Co Ltd China) with a conductivity lessthan 1times 10minus 4 Smiddotmminus 1 and pHasymp 660 at 25degC was used duringthe whole experiment On the basis of the method describedin the literature [16] β-CsB5O8middot4H2O was successfullysynthesized in our laboratory A certain amount of Cs2CO3was added to a solution of H3BO3 in which the molar rationof Cs2CO3 H3BO3 is 1 10 followed by stirring at roomtemperature for homogeneity and heated to the boilingpoint for releasing CO2 1en the solution was stirred at60degC for 24 h to precipitate out of the solid phase Finally theprecipitates were filtered recrystallized washed with DDWas well as absolute ethyl alcohol separately and dried at 30degCto obtain the samples In addition the samples were dried at50degC and atmospheric pressure until the weight was con-stant and then cooled down to room temperature to store inthe desiccators for use

22 Characterization 1e synthesized CsB5O8middot4H2O wasidentified by the X-ray diffractometer (MSAL XD-3 BeijingPurkinje Instrument Co Ltd China) with Cu-Kα radiationat 4 minminus 1 in the scan range of 2θ from 5 to 70deg and the

results are shown in Figure 1 and it can clearly be seen thatthe peak position and intensity of the synthesizedCsB5O8middot4H2O were in great agreement with the standardmap (22ndash0175) indicating that the compound forCsB5O8middot4H2O is the beta phase (β-CsB5O8middot4H2O) [16] TGand DSC were conducted by SETARAM LABSYS thermalanalyzer under an N2 atmosphere with a heating rate of10Kmiddotminminus 1 from 29815 to 82315K as shown in Figure 2Furthermore the output of water molecules proceeds in twostages [17] 1e first stage is observed from 393K to 473Kwith a loss of three water molecules and the compoundtransforms into the amorphous and the second stage isobserved with the loss of only one water molecule 1e totalweight loss of the sample was 01863 in mass fraction whichis essentially consistent with the theoretical value of 01862the deviation being only 005

1e concentration of B2O3 was determined by themannitol gravimetric method with a known content ofNaOH aqueous solution in the presence of double indicatorof methyl red and phenolphthalein with the standard un-certainty of 00005 in mass fraction [18] and the reactionequation can be written as follows 1e content for cesiumion was measured by inductively coupled plasma opticalemission spectrometer (Prodigy Leman CorporationAmerica) with a precision of plusmn0005 in mass fraction 1eH2O content was calculated through differential subtractionand the calculated value of 1863 corresponds to the fourwater molecules 1e chemical analysis results presented inTable 2 together with the X-ray diffractometer map and TGanalysis testify that the purity of the synthesizedβ-CsB5O8middot4H2O reaches 0995 in mass fraction

H3BO3 + C6H14O6⟶ C6H8(OH)2 middot BO3H( 11138572 + 4H2O

C6H8(OH)2 middot BO3H( 11138572 + NaOH⟶ C6H8(OH)2 middot BO3Na( 11138572 + 4H2O(1)

23 Apparatus and Procedure A high-precision adiabaticmicrocalorimeter (BT215 SETARAM France) whichmainly comprised a calorimetric chamber electrical orpneumatic peripherals and the liquid nitrogen supply wasemployed for measuring the heat capacity ofβ-CsB5O8middot4H2O over the temperature range of 298 to 373Kwith a heating rate of 01 Kmin under nitrogen atmosphereand the sample mass in the sample cell used for the heatcapacity measurement was 1604401mg weighted with anaccuracy of 000001 g To verify the accuracy of the calo-rimeter the heat capacity of a reference standard material(KCl) was carried out at 29815K where the average result is06876 Jmiddotgminus 1middotKminus 1 for seven times which agrees well with06879 Jmiddotgminus 1middotKminus 1 reported in the literature [19] and thedeviation is 00004

3 Results and Discussion

31 Heat Capacity 1e values for the molar heat capacity ofβ-CsB5O8middot4H2Omeasured by the adiabatic calorimeter from

298 to 373Kwith the standard uncertainty of 005 Jmiddotmolminus 1middotKminus 1

are listed in Table 3 and plotted in Figure 3 As shown inFigure 3 the heat capacities of β-CsB5O8middot4H2O increaseslowly in the rise of temperature from 298 to 373K whichshows that the structure of β-CsB5O8middot4H2O is stable in thistemperature region that is no phase transition is observedand no other thermal anomalies take place within the tem-perature range of the experiment Compared with theCs2B4O7middot5H2O as well as LiB5O8middot5H2O [7 10] the molar heatcapacity of β-CsB5O8middot4H2O is much larger than that ofCs2B4O7middot5H2O from 303 to 335K and that of LiB5O8middot5H2O issmaller than that of Cs2B4O7middot5H2O and β-CsB5O8middot4H2O atthe same temperature For β-CsB5O8middot4H2O andCs2B4O7middot5H2O the types of elements are the same includingthe cesium boron hydrogen and oxygen and the distinctionin the heat capacity may be caused by the diverse internalstructures of the molecules However for β-CsB5O8middot4H2Oand LiB5O8middot5H2O cesium and lithium belong to the samegroup and the radius of cesium ion is larger than that oflithium ion resulting in more electrons around the cesium

2 Journal of Chemistry

ion which leads to the difference of the energy when thetemperature varies and further causes the imparity of heatcapacity 1erefore the molar heat capacities ofCs2B4O7middot5H2O and β-CsB5O8middot4H2O are larger than that ofLiB5O8middot5H2O

In order to obtain the heat capacity quickly at a certaintemperature the molar heat capacity of β-CsB5O8middot4H2Odetermined in this work has been fitted by means of a least-squares method and the polynomial equation with thecorrelation coefficient r 099722 can be expressed asfollows

Cpm Jmiddotmolminus 1middotK

minus 11113872 1113873 61807702 + 3952669

T minus T max + Tmin( 11138572( 11138571113858 1113859

T max minus Tmin( 111385721113858 1113859

minus 346888T minus T max + Tmin( 1113857 2( 11138571113858 1113859

T max minus Tmin( 111385721113858 11138591113896 1113897

2

+ 79441T minus T max + Tmin( 1113857 2( 11138571113858 1113859

T max minus Tmin( 111385721113858 11138591113896 1113897

3

(2)

where Cpm is the molar heat capacity of β-CsB5O8middot4H2O(Jmiddotmolminus 1middotKminus 1) T is the thermodynamic temperature (K) andTmax and Tmin are the maximum and minimum in the ex-perimental temperature range which are 37301 and29802K respectively According to the above equation themolar heat capacity of β-CsB5O8middot4H2O at 29815K can becalculated as 56737 Jmiddotmolminus 1middotKminus 1 and the standard deviations

between experimental values Cpexp and fitted values Cpfitthrough the polynomial equation are within 0005 as shownin Figure 4

32 0ermodynamic Functions 1ermodynamic functions(HT minus H29815) (ST minus S29815) and (GT minus G29815) of

Table 1 Reagents used in the study

Chemicals CAS regno

Initial mass fractionpurity Purification method Final mass fraction

purity Analysis method

H3BO3a 10043-35-3 09999 Without

purification 09999 Gravimetric method for boron

CsCO3b 534-17-8 09990 Without

purification 09990 Gravimetric method forcarbonate

β-CsB5O8middot4H2Oc mdash 09900 Recrystallization 09950 Gravimetric method for boronaFrom the Shanghai Macklin Biochemical Co Ltd bFrom the Aladdin Industrial Co Ltd cSynthesized in our laboratory

0

250

500

750

1000

22-0175 gt Cs2B10O168H2O - Cesium borate hydrate

10 20 30 40 50 602-Theta (deg)

Inte

nsity

(cou

nts)

Figure 1 1e X-ray diffraction pattern of β-CsB5O8middot4H2O

Journal of Chemistry 3

300 400 500 600 700 800 900

80

85

90

95

100

Hea

t flow

(mW

)

0

10

20

30

40

50

Wei

ght p

erce

nt (

)

T (K)

ndash3H2O

ndash1H

2O

Figure 2 1e TG and DSC curve of β-CsB5O8middot4H2O

Table 2 Chemical analytical results of β-CsB5O8middot4H2O in mass fractiona

CsB5O8middot4H2O Cs2O B2O3 H2O n (Cs2O B2O3 H2O)Experimental 03663 04474 01863 100 494 7961eoretical 03641 04497 01862 100 500 800Relative error () 060 050 005 mdashaStandard uncertainties u are u(Cs2O) 00053 u(B2O3) 00005 and u(H2O) 00055 in mass fraction

Table 3 Molar heat capacity of β-CsB5O8middot4H2O (molecular mass M 38695 gmiddotmolminus 1)

T (K)a Cpm (Jmiddotmolminus 1middotKminus 1) T (K) Cpm (Jmiddotmolminus 1middotKminus 1) T (K) Cpm (Jmiddotmolminus 1middotKminus 1)29802 56549 32404 60612 35001 6320829901 56742 32505 60788 35101 6340630001 56935 32600 60830 35204 6359930106 57166 32701 60928 35300 6368130201 57385 32802 60980 35406 6389430305 57571 32908 61097 35502 6409330400 57775 33006 61201 35604 6421230501 57977 33104 61225 35704 6431930601 58149 33200 61400 35804 6448330707 58369 33300 61471 35901 6460830801 58550 33401 61594 36003 6479030901 58648 33500 61634 36108 6483031006 58854 33604 61734 36207 6493931106 59000 33708 61849 36304 6503931202 59122 33805 61912 36403 6511731310 59250 33897 62037 36500 6519831401 59308 34002 62115 36605 6525231507 59396 34106 62230 36707 6530131607 59569 34208 62374 36814 6543531701 59706 34305 62455 36921 6552331801 59819 34402 62564 37012 6569431907 59967 34510 62627 37101 6578332003 60175 34601 62705 37202 6582732104 60234 34706 62844 37302 6590732201 60382 34803 6296432302 60484 34901 63144aUncertainty of temperature u(T) 001K and the molar heat capacity uncertainty u(Cpm) 005 Jmiddotmolminus 1middotKminus 1


300 310 320 330 340 350 360 370

570580590600610620630640650660

C pm

(Jmiddotm

olndash1

middotKndash1

)

T (K)

Figure 3 Experimental molar heat capacity of β-CsB5O8middot4H2O in the range of 298 to 373K

300 310 320 330 340 350 360 370

ndash04

ndash02

00

02

04

T (K)

(Cp

exp ndash

Cp

fit)

C pfi

t times 1

00

Figure 4 1e deviations of the experimental and fitting values

Table 4 Molar heat capacity and thermodynamic functions of β-CsB5O8middot4H2O

T (K) Cpm (Jmiddotmolminus 1middotKminus 1) HT minus H29815 (kJmiddotmolminus 1) ST minus S29815 (Jmiddotmolminus 1middotKminus 1) GT minus G29815 (kJmiddotmolminus 1)29815 56737 000 000 000300 57077 minus 1046 6361 minus 2955305 57932 minus 3784 23399 minus 10921310 58706 minus 6393 40210 minus 18858315 59410 minus 8877 56793 minus 26767320 60056 minus 11240 73147 minus 34647325 60654 minus 13484 89272 minus 42498330 61216 minus 15615 105166 minus 50320335 61753 minus 17635 120830 minus 58113340 62276 minus 19548 136263 minus 65878345 62798 minus 21357 151466 minus 73613350 63328 minus 23066 166439 minus 81320355 63879 minus 24678 181182 minus 88997360 64462 minus 26196 195695 minus 96646365 65087 minus 27623 209980 minus 104266370 65767 minus 28963 224036 minus 111856375 66512 minus 30218 237866 minus 119418


β-CsB5O8middot4H2O relative to the standard status (29815K and01MPa) were obtained according to the following ther-modynamic equations

HT minus H29815 1113946T

29815CpmdT

ST minus S29815 1113946T

29815

Cpm

T1113890 1113891dT

GT minus G29815 1113946T

29815CpmdT minus T 1113946

T

29815

Cpm

T1113890 1113891dT

(3)

1e polynomial fitted values for the molar heat capacityand thermodynamic functions of β-CsB5O8middot4H2O are ob-tained in the temperature range from 298 to 375K at in-tervals of 5 K and listed in Table 4 It can clearly be seen thatfrom Table 4 the values of the molar heat capacity andentropy (ST minus S29815) are increased with the increase oftemperature from 29815K to 375K but the enthalpy(HT minus H29815) and Gibbs free energy (GT minus G29815) aredecreased

4 Conclusions

1emolar heat capacities of β-CsB5O8middot4H2O were measuredby an adiabatic calorimeter in the temperature range from298 to 373K with a heating rate of 01 Kmin without thephase transition and other thermal anomalies and were fittedto a polynomial equation of Cpm (Jmiddotmolminus 1middotKminus 1)

61807702 + 3952669[T minus (Tmax +Tmin)2](Tmax minus Tmin)2]minus346888[(T minus (Tmax +Tmin)2)(Tmax minus Tmin)2]2 + 79441[(T minus

(Tmax +Tmin)2)(Tmax minus Tmin)2]3 1e relevant thermody-namic functions of enthalpy entropy and Gibbs free energyof cesium pentaborate tetrahydrate are also obtained at in-tervals of 5K from 298 to 375K

Data Availability

1e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

1e authors declare that they have no conflicts of interest

Acknowledgments

Financial supports from the National Natural Science Foun-dation of China (21773170 and U1607123) the Key Projects ofNatural Science Foundation of Tianjin (18JCZDJC10040) andthe Yangtze Scholars and Innovative Research Team inChineseUniversity (IRT_17R81) are acknowledged

References

[1] D L Shen X P Yu Y F Guo S Q Wang and T L DengldquoBoron and its compounds in new energy and materialsfieldsrdquo Applied Mechanics and Materials vol 71ndash78pp 2594ndash2597 2011

[2] J Peng S Bian B Zhang Y Dong and W Li ldquoResearch onboron recovery from sulfate-type saline lakes with a noveldilution methodrdquo Hydrometallurgy vol 174 pp 47ndash55 2017

[3] Y Bing G S Wang and Y W Tian ldquoResearch process of rareearth borate luminescent materialsrdquo Materials Review vol 1pp 34ndash37 2013

[4] B L Liu D Liu H F Ji W D Wang and H L Xu ldquoDe-velopment of borate functional materialsrdquo GuangzhouChemical Industry vol 42 pp 12ndash14 2014

[5] X R Zhang S X Zhang and Y Chai ldquoStudy on newnonlinear optical crystalndashcesium lithum boraterdquo Journal ofSynthetic Crystals vol 27 pp 26ndash30 1998

[6] G Yin Y Yao B Jiao S Chen and S Gao ldquoEnthalpies ofdilution of aqueous Li2B4O7 solutions at 29815 K and ap-plication of ion-interaction modelrdquo 0ermochimica Actavol 435 no 2 pp 125ndash128 2005

[7] W Cui L Li Y Guo S Zhang and T Deng ldquoHeat capacity andthermodynamic property of lithium pentaborate pentahydraterdquoJournal of Chemistry vol 2018 Article ID 7962739 4 pages 2018

[8] Z-H Zhang Z-C Tan G Y Yin Y Yao L-X Sun andY-S Li ldquoHeat capacities and thermodynamic functions of theaqueous Li2B4O7 solution in the temperature range from 80 Kto 355 Krdquo Journal of Chemical amp Engineering Data vol 52no 3 pp 866ndash870 2007

[9] Z-H Zhang G-Y Yin Z-C Tan Y Yao and L-X Sun ldquoHeatcapacities and thermodynamic properties of a H2O + Li2B4O7solution in the temperature range from 80 to 356 Krdquo Journal ofSolution Chemistry vol 35 no 10 pp 1347ndash1355 2006

[10] K Sun K Zhao L Li Y Guo and T Deng ldquoHeat capacity andthermodynamic property of cesium tetraborate pentahydraterdquoJournal of Chemistry vol 2019 Article ID 9371328 5 pages 2019

[11] Y Guo K Zhao L Li et al ldquoVolumetric properties ofaqueous solution of lithium tetraborate from 28315 to36315 K at 101325 kPardquo 0e Journal of Chemical 0ermo-dynamics vol 120 pp 151ndash156 2018

[12] K Zhao L Li Y Guo et al ldquoApparent molar volumes ofaqueous solutions of lithium pentaborate from 28315 to36315 K and 101325 kPa an experimental and theoreticalstudyrdquo Journal of Chemical amp Engineering Data vol 64 no 3pp 944ndash951 2019

[13] J Li B Li and S Gao ldquo1ermochemistry of hydrated po-tassium and sodium boratesrdquo 0e Journal of Chemical0ermodynamics vol 30 no 4 pp 425ndash430 1998

[14] Z Liu S Li and M Hu ldquo1ermodynamic properties ofCs2[B4O5(OH)4]middot3H2Ordquo 0e Journal of Chemical 0ermo-dynamics vol 37 no 9 pp 1003ndash1006 2005

[15] L X Zhu T Yue S Y Gao and S P Xia ldquo1ermochemistryof hydrated rubidium tetraboraterdquo Journal of Chemical0ermodynamics vol 404 pp 259ndash263 2003

[16] N Penin L Seguin B Gerand M Touboul andG Nowogrocki ldquoCrystal structure of a new form of Cs[B5O6(OH)4]middot2H2O and thermal behavior of M[B5O6(OH)4]middot2H2O (M Cs Rb Tl)rdquo Journal of Alloys and Compoundsvol 334 no 1-2 pp 97ndash109 2002

[17] Y E Anderson S K Filatov I G Polyakova andR S Bubnova ldquo1ermal behavior of M + B5O6(OH)4middot2H2O(M+K Rb Cs) and polymorphic transformations ofCsB5O8rdquo Glass Physics and Chemistry vol 30 no 5pp 450ndash460 2004

[18] Qinghai Institute of Salt Lakes of CAS Analytical Methods ofBrines and Salts Chinese Science Press Beijing China 2ndedition 1988

[19] J G Speight Langersquos Handbook of Chemistry McGraw-HillNew York NY USA 16th edition 2005


tetrahydrate In this paper the heat capacity and the relatedthermodynamic functions of enthalpy entropy and Gibbsfree energy for β-CsB5O8middot4H2O have been determined forthe first time

2 Experimental

21 Materials 1e purity degree and purification of thechemicals used in this work are tabulated in Table 1 1edoubly deionized water (DDW) produced by ULUP-II-10T(Chongqing Jiuyang Co Ltd China) with a conductivity lessthan 1times 10minus 4 Smiddotmminus 1 and pHasymp 660 at 25degC was used duringthe whole experiment On the basis of the method describedin the literature [16] β-CsB5O8middot4H2O was successfullysynthesized in our laboratory A certain amount of Cs2CO3was added to a solution of H3BO3 in which the molar rationof Cs2CO3 H3BO3 is 1 10 followed by stirring at roomtemperature for homogeneity and heated to the boilingpoint for releasing CO2 1en the solution was stirred at60degC for 24 h to precipitate out of the solid phase Finally theprecipitates were filtered recrystallized washed with DDWas well as absolute ethyl alcohol separately and dried at 30degCto obtain the samples In addition the samples were dried at50degC and atmospheric pressure until the weight was con-stant and then cooled down to room temperature to store inthe desiccators for use

22 Characterization 1e synthesized CsB5O8middot4H2O wasidentified by the X-ray diffractometer (MSAL XD-3 BeijingPurkinje Instrument Co Ltd China) with Cu-Kα radiationat 4 minminus 1 in the scan range of 2θ from 5 to 70deg and the

results are shown in Figure 1 and it can clearly be seen thatthe peak position and intensity of the synthesizedCsB5O8middot4H2O were in great agreement with the standardmap (22ndash0175) indicating that the compound forCsB5O8middot4H2O is the beta phase (β-CsB5O8middot4H2O) [16] TGand DSC were conducted by SETARAM LABSYS thermalanalyzer under an N2 atmosphere with a heating rate of10Kmiddotminminus 1 from 29815 to 82315K as shown in Figure 2Furthermore the output of water molecules proceeds in twostages [17] 1e first stage is observed from 393K to 473Kwith a loss of three water molecules and the compoundtransforms into the amorphous and the second stage isobserved with the loss of only one water molecule 1e totalweight loss of the sample was 01863 in mass fraction whichis essentially consistent with the theoretical value of 01862the deviation being only 005

1e concentration of B2O3 was determined by themannitol gravimetric method with a known content ofNaOH aqueous solution in the presence of double indicatorof methyl red and phenolphthalein with the standard un-certainty of 00005 in mass fraction [18] and the reactionequation can be written as follows 1e content for cesiumion was measured by inductively coupled plasma opticalemission spectrometer (Prodigy Leman CorporationAmerica) with a precision of plusmn0005 in mass fraction 1eH2O content was calculated through differential subtractionand the calculated value of 1863 corresponds to the fourwater molecules 1e chemical analysis results presented inTable 2 together with the X-ray diffractometer map and TGanalysis testify that the purity of the synthesizedβ-CsB5O8middot4H2O reaches 0995 in mass fraction

H3BO3 + C6H14O6⟶ C6H8(OH)2 middot BO3H( 11138572 + 4H2O

C6H8(OH)2 middot BO3H( 11138572 + NaOH⟶ C6H8(OH)2 middot BO3Na( 11138572 + 4H2O(1)

23 Apparatus and Procedure A high-precision adiabaticmicrocalorimeter (BT215 SETARAM France) whichmainly comprised a calorimetric chamber electrical orpneumatic peripherals and the liquid nitrogen supply wasemployed for measuring the heat capacity ofβ-CsB5O8middot4H2O over the temperature range of 298 to 373Kwith a heating rate of 01 Kmin under nitrogen atmosphereand the sample mass in the sample cell used for the heatcapacity measurement was 1604401mg weighted with anaccuracy of 000001 g To verify the accuracy of the calo-rimeter the heat capacity of a reference standard material(KCl) was carried out at 29815K where the average result is06876 Jmiddotgminus 1middotKminus 1 for seven times which agrees well with06879 Jmiddotgminus 1middotKminus 1 reported in the literature [19] and thedeviation is 00004

3 Results and Discussion

31 Heat Capacity 1e values for the molar heat capacity ofβ-CsB5O8middot4H2Omeasured by the adiabatic calorimeter from

298 to 373Kwith the standard uncertainty of 005 Jmiddotmolminus 1middotKminus 1

are listed in Table 3 and plotted in Figure 3 As shown inFigure 3 the heat capacities of β-CsB5O8middot4H2O increaseslowly in the rise of temperature from 298 to 373K whichshows that the structure of β-CsB5O8middot4H2O is stable in thistemperature region that is no phase transition is observedand no other thermal anomalies take place within the tem-perature range of the experiment Compared with theCs2B4O7middot5H2O as well as LiB5O8middot5H2O [7 10] the molar heatcapacity of β-CsB5O8middot4H2O is much larger than that ofCs2B4O7middot5H2O from 303 to 335K and that of LiB5O8middot5H2O issmaller than that of Cs2B4O7middot5H2O and β-CsB5O8middot4H2O atthe same temperature For β-CsB5O8middot4H2O andCs2B4O7middot5H2O the types of elements are the same includingthe cesium boron hydrogen and oxygen and the distinctionin the heat capacity may be caused by the diverse internalstructures of the molecules However for β-CsB5O8middot4H2Oand LiB5O8middot5H2O cesium and lithium belong to the samegroup and the radius of cesium ion is larger than that oflithium ion resulting in more electrons around the cesium





minus 11113872 1113873 61807702 + 3952669

T minus T max + Tmin( 11138572( 11138571113858 1113859

T max minus Tmin( 111385721113858 1113859


T max minus Tmin( 111385721113858 11138591113896 1113897

2

+ 79441T minus T max + Tmin( 1113857 2( 11138571113858 1113859

T max minus Tmin( 111385721113858 11138591113896 1113897

3

(2)





Chemicals CAS regno



H3BO3a 10043-35-3 09999 Without





0

250

500

750

1000


10 20 30 40 50 602-Theta (deg)

Inte

nsity

(cou

nts)



300 400 500 600 700 800 900

80

85

90

95

100

Hea

t flow

(mW

)

0

10

20

30

40

50

Wei

ght p

erce

nt (

)

T (K)

ndash3H2O

ndash1H

2O







300 310 320 330 340 350 360 370

570580590600610620630640650660

C pm

(Jmiddotm

olndash1

middotKndash1

)

T (K)


300 310 320 330 340 350 360 370

ndash04

ndash02

00

02

04

T (K)

(Cp

exp ndash

Cp

fit)

C pfi

t times 1

00






HT minus H29815 1113946T

29815CpmdT

ST minus S29815 1113946T

29815

Cpm

T1113890 1113891dT

GT minus G29815 1113946T


T

29815

Cpm

T1113890 1113891dT

(3)


4 Conclusions




Data Availability




Acknowledgments


References
























minus 11113872 1113873 61807702 + 3952669

T minus T max + Tmin( 11138572( 11138571113858 1113859

T max minus Tmin( 111385721113858 1113859


T max minus Tmin( 111385721113858 11138591113896 1113897

2

+ 79441T minus T max + Tmin( 1113857 2( 11138571113858 1113859

T max minus Tmin( 111385721113858 11138591113896 1113897

3

(2)





Chemicals CAS regno



H3BO3a 10043-35-3 09999 Without





0

250

500

750

1000


10 20 30 40 50 602-Theta (deg)

Inte

nsity

(cou

nts)



300 400 500 600 700 800 900

80

85

90

95

100

Hea

t flow

(mW

)

0

10

20

30

40

50

Wei

ght p

erce

nt (

)

T (K)

ndash3H2O

ndash1H

2O







300 310 320 330 340 350 360 370

570580590600610620630640650660

C pm

(Jmiddotm

olndash1

middotKndash1

)

T (K)


300 310 320 330 340 350 360 370

ndash04

ndash02

00

02

04

T (K)

(Cp

exp ndash

Cp

fit)

C pfi

t times 1

00






HT minus H29815 1113946T

29815CpmdT

ST minus S29815 1113946T

29815

Cpm

T1113890 1113891dT

GT minus G29815 1113946T


T

29815

Cpm

T1113890 1113891dT

(3)


4 Conclusions




Data Availability




Acknowledgments


References





















300 400 500 600 700 800 900

80

85

90

95

100

Hea

t flow

(mW

)

0

10

20

30

40

50

Wei

ght p

erce

nt (

)

T (K)

ndash3H2O

ndash1H

2O







300 310 320 330 340 350 360 370

570580590600610620630640650660

C pm

(Jmiddotm

olndash1

middotKndash1

)

T (K)


300 310 320 330 340 350 360 370

ndash04

ndash02

00

02

04

T (K)

(Cp

exp ndash

Cp

fit)

C pfi

t times 1

00






HT minus H29815 1113946T

29815CpmdT

ST minus S29815 1113946T

29815

Cpm

T1113890 1113891dT

GT minus G29815 1113946T


T

29815

Cpm

T1113890 1113891dT

(3)


4 Conclusions




Data Availability




Acknowledgments


References





















300 310 320 330 340 350 360 370

570580590600610620630640650660

C pm

(Jmiddotm

olndash1

middotKndash1

)

T (K)


300 310 320 330 340 350 360 370

ndash04

ndash02

00

02

04

T (K)

(Cp

exp ndash

Cp

fit)

C pfi

t times 1

00






HT minus H29815 1113946T

29815CpmdT

ST minus S29815 1113946T

29815

Cpm

T1113890 1113891dT

GT minus G29815 1113946T


T

29815

Cpm

T1113890 1113891dT

(3)


4 Conclusions




Data Availability




Acknowledgments


References






















HT minus H29815 1113946T

29815CpmdT

ST minus S29815 1113946T

29815

Cpm

T1113890 1113891dT

GT minus G29815 1113946T


T

29815

Cpm

T1113890 1113891dT

(3)


4 Conclusions




Data Availability




Acknowledgments


References





















heat capacity and thermodynamic properties of cesium ...ion, which leads to the diﬀerence of the...

Documents