Electrometric investigations on formation of lanthanum molybdates as a function of Ph

Journal of the Brazilian Chemical Society

Shiva Prasad²  Valderí D. Leite¹  Renato A.c. De Santana²  Joelma B. Brito² 

[1] ,Universidade Federal de Campina Grande Centro de Ciências e Tecnologia Departamento de Engenharia QuímicaCampina Grande PB ,Brazil

关键词: molybdates;    lanthanum molybdates;    electrometry;   

DOI  :  10.1590/S0103-50532004000200014

来源: SciELO

【 摘 要 】

The precise nature of the reaction between lanthanum nitrate and sodium molybdate at specific pH levels 7.6, 5.5 and 4.1 has been studied by means of electrometric techniques involving potentiometric and conductometric titrations, in aqueous and alcoholic media using each reagent as titrant. Well-defined breaks and inflections in the titration curves provide cogent evidence for formation and precipitation of lanthanum normal-La2O3.3MoO3, para- La2O3.7MoO3 and octa-2 La2O3.24MoO3 molybdates in the vicinity of pH 5.9, 4.8 and 4.2, respectively. Analytical investigations of the precipitates of lanthanum molybdates have also been carried out, which substantiate the results of the electrometric study.

【 授权许可】

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