What is the molarity of pure water at 20 C?density table of water

 molarity of pure water

   density of water is at 20 C = 0.9982071 gram /ml

let we take 1 liter water 

                                   1 liter = 1000 ml 

            mass of 1 liter water = volume *density  

                                             = 1000 ml * 0.9982071 gram /ml 

                                             =  998.2071 gram

  molar mass of water  H2O = 2* 1.008 + 15.999

                                             = 18.015 gram / moles

number of moles of water in one liter 

                                            = mass of substance / molar mass

                                            = 998.2071 gram/18.015 (gram / moles)

                                            =55.41 moles 

        molarity of water        = number of moles of water / volume of water 

                                           = 55.41 moles/ 1liter 

                                           = 55.41moles/liter

Answer:-  molarity of water at 20 C is 55.41M