RAJASTHAN PMT Rajasthan - PMT Solved Paper-2005

  • question_answer
    Sodium pyrophosphate is represented by which of the following formula?

    A) \[N{{a}_{2}}{{P}_{2}}{{O}_{4}}\]                               

    B) \[N{{a}_{4}}{{P}_{2}}{{O}_{5}}\]

    C) \[N{{a}_{4}}{{P}_{2}}{{O}_{7}}\]               

    D)        \[N{{a}_{2}}{{P}_{2}}{{O}_{5}}\]

    Correct Answer: C

    Solution :

    Sodium pyrophosphate is represented by\[N{{a}_{4}}{{P}_{2}}{{O}_{7}}\]. It is sodium salt of pyrophosphoric acid\[({{H}_{4}}{{P}_{2}}{{O}_{7}})\], which may be considered to be made up by two molecules of orthro phosphoric acid\[({{H}_{3}}P{{O}_{4}})\], eliminating one molecule of\[{{H}_{2}}O\].                 \[2{{H}_{3}}P{{O}_{4}}\xrightarrow{-{{H}_{2}}O}\underset{Pyrophosphoric\,\,acid}{\mathop{{{H}_{4}}{{P}_{2}}{{O}_{7}}}}\,\]                 \[\underset{Sodium\,\,pyrophosphate}{\mathop{O\leftarrow \underset{\begin{align}   & | \\  & O \\  & | \\  & Na \\ \end{align}}{\overset{\begin{align}   & Na \\  & | \\  & O \\  & | \\ \end{align}}{\mathop{P}}}\,-O-\underset{\begin{align}   & | \\  & O \\  & | \\  & Na \\ \end{align}}{\overset{\begin{align}   & Na \\  & | \\  & O \\  & | \\ \end{align}}{\mathop{P}}}\,\to O}}\,\]


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