Aquantity of 85.0 ml of 0.900 m hcl is mixed with 85.0 ml of 0.900 m koh in a constantpressure calorimeter that has a heat capacity of 325 j/°c. if the initial temperatures of both solutions are the same at 18.24°c, what is the final temperature of the mixed solution? the heat of neutralization is −56.2 kj/mol. assume the density and specific heat of the solutions are the same as those for water.

Explanation:

The given data is as follows.

          = 85.0 ml,         = 0.9 M

          = 85.0 ml,         = 0.9 M

Hence, number of moles of HCl and KOH will be the same because both the solutions have same volume and molarity.

So,     No. of moles = Molarity × Volume

                                =        (as 1 L = 1000 ml so, 85 ml = 0.085 L)

                                = 0.076 mol

As 1 mole gives 56.2 kJ/mol of heat of neutralization. Hence, calculate the heat of neutralization given by 0.076 moles as follows.

                    = 4.271 kJ

or,                 = 4271 J     (as 1 kJ = 1000 J)

Therefore,    heat released = - heat of gained by calorimeter

Since, it is given that density of the solution is similar to the density of water which is 1 g/ml.

Hence,     mass of HCl = density × Volume of HCl

                                      = 1.00 g/ml × 85.0 ml

                                       = 85 g

Similarly,    mass of KOH = = density × Volume of HCl

                                      = 1.00 g/ml × 85.0 ml

                                       = 85 g

Hence, total mass of the solution = 85 g + 85 g

                                                        = 170 g

Also,                   q =

                     4271 J =    

                     0.0773 =

                    =  

Thus, we can conclude that final temperature of the mixed solution is .

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