An amount of solid barium chloride, 20.8 g, is dissolved in 100 g water in a coffee-cup calorimeter by the reaction: bacl2 (s)  ba2+(aq) + 2cl−(aq) the water is originally at 25.0 °c and after the reaction the temperature of the solution is 26.6 °c. (cs = 4.04 j/(g°c) for the solution). what is the enthalpy change (δh) associated with the reaction as written?

Answer : The enthalpy change during the reaction is -6.48 kJ/mole

Explanation :

First we have to calculate the heat gained by the reaction.

where,

q = heat gained = ?

m = mass of water = 100 g

c = specific heat =

= final temperature =

= initial temperature =

Now put all the given values in the above formula, we get:

Now we have to calculate the enthalpy change during the reaction.

where,

= enthalpy change = ?

q = heat gained = 23.4 kJ

n = number of moles barium chloride =

Therefore, the enthalpy change during the reaction is -6.48 kJ/mole