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化学学报
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化学学报 ›› 2010, Vol. 68 ›› Issue (07): 722-726. 上一篇    

研究简报

VOSO4•2.76H2O(s)在水和硫酸水溶液中的溶解焓

刘建国，秦野，严川伟   

  1. (中国科学院金属研究所 金属腐蚀与防护国家重点实验室 沈阳 110016)
  • 投稿日期:2009-08-29 修回日期:2009-10-12 发布日期:2010-04-14
  • 通讯作者: 严川伟 E-mail:cwyan@pub.ln.cninfo.net
  • 基金资助:

    国家重点基础研究发展计划(No.2010CB227203)

Enthalpies of Solution for VOSO4•2.76H2O(s) in Water and in Aqueous H2SO4

Liu Jianguo Qin Ye Yan Chuanwei   

  1. (State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016)
  • Received:2009-08-29 Revised:2009-10-12 Published:2010-04-14

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在298.15 K下利用具有恒温环境的溶解-反应热量计, 测定了VOSO4•2.76H2O(s)在水和0.5 mol•kg－1硫酸水溶液中的摩尔溶解焓. 在硫酸水溶液中VOSO4•2.76H2O(s)摩尔溶解焓的负值比在纯水中要小很多, 这说明VOSO4在硫酸水溶液中具有较高的能量状态. 借助VOSO4水溶液的离子缔合平衡和硫酸的二级解离平衡, 改进了Archer方法, 并用这种改进的方法分别估算了VOSO4•2.76H2O(s)在水中的标准摩尔溶解焓＝－29.18 kJ•mol－1, 以及在0.5 mol•kg－1硫酸水溶液中的标准摩尔溶解焓＝－25.79 kJ•mol－1. 根据离子缔合平衡和硫酸二级解离平衡的计算结果, 硫酸根离子浓度受到硫酸二级解离平衡控制, 使部分[VOSO4]0离子对解离, 致使硫酸氧钒-硫酸水溶液中的自由氧钒离子(VO2＋)增加.

关键词: 钒氧化还原液流电池, 溶解焓, 硫酸氧钒, 硫酸

The molal enthalpies of solution of VOSO4•2.76H2O(s) with various molalities in water and in aqueous sulfuric acid (0.5 mol•kg－1), ΔsHm, were measured by a solution-reaction isoperibol calorimeter at 298.15 K. The value of －ΔsHm in aqueous sulfuric acid was lower than that in water, which shows that energy state of VOSO4 in aqueous H2SO4 was higher than that in pure water. An improved Archer s method was put forward in terms of ionic association equilibrium of VOSO4 and second dissociation equilibrium of H2SO4. Using the improved method, the standard molal enthalpies of solution ＝－29.18 kJ•mol－1 in pure water and ＝－25.79 kJ•mol－1 in aqueous sulfuric acid were obtained, respectively. According to calculation, the molality of VO2＋ was larger in VOSO4-H2SO4 mixed solution than that in water.

Key words: vanadium redox, battery, enthalpy of solution, vanadyl sulfate, sulfuric acid