How many moles is 1.50x10^23 molecules of nh3?

 The   number  of moles that are  1.50  x10^23  molecules of NH3  are  

 =0.249 moles

        calculation

 The number of  moles is calculated  using  Avogadro's  law  constant

that  is  According  to Avogadro's  law

                         1  moles  of a  substance = 6.02 x10^23  molecules

                                    ?    moles                =  1.50  x10^23  molecules

by  cross  multiplication

= [( 1.50  x 10^23  molecules  x  1 moles) / (6.02 x10^23)]  = 0.249  moles

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.

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