Answer :

Average rate =   - d reactant/d time + d product/d time

negative sign indicates that decrease in concentration of reactant and positive sign shows the increment in concentration of product

d represents the change in concentration,  t represents time

Considering the reaction

2H3PO4→P2O5+3H2O

rate =  d ( p^2o^5)/ d t

     =  (p^2o^5) 40 sec -  (p^2o^5) 10 sec / 30  

  =  7.0 * 10^-3- 1.10 * 10^-3/30

  rate = 2 * 10^-4m/s

2H3PO4→P2O5+3H2O

rate = - d H3PO4/2t  = d ( p^2o^5)/ d t

d H3PO4/t = 2 *  d ( p^2o^5)/ d t

          = 2 * 2 * 10^-4

         = 4 * 10^4 m/s

To know more about  concentration   visit : https://brainly.com/question/10725862

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