A0.158 g sample of magnesium metal reacts completely with 100.0 ml of 1.0 m hydrochloric acid in a coffee cup calorimeter. the temperature of the solution rose from 25.6°c to 32.8°c. what is ∆hrxn? assume the specific heat of the solution is 4.184 j/mol-k and the density is 1.0 g/ml.

Explanation:

The given data is as follows.

     mass = 0.158 g,      volume = 100 ml

     Molarity = 1.0 M,       =  

The given reaction is as follows.

So, moles of magnesium will be calculated as follows.

         No. of moles =                            

                               =

                               =

                               = 0.0065 mol

Now, formula for heat released is as follows.

              Q =

                  =

                  =

                  = 3010.32 J

Hence, heat of reaction will be calculated as follows.

                      =

                      = -4.63 J/mol

or,                  =                (as 1 kJ = 1000 J)

Thus, we can conclude that heat of given reaction is kJ/mol.    

the answer is either b or c