please solve the following , thank you. Calorimetry is a method used to measure

Question

please solve the following , thank you.

Calorimetry is a method used to measure changes in enthalpy, or heat that occur during chemical processes. Two common calorimeters are constant pressure calorimeters and constant-volume (or "bomb") calorimeters. Bomb calorimeters are used to measure combustion and other gas-producing reactions, in which the reaction is observed in a strong, sealed vessel. A simple constant-pressure calorimeter can be made from a foam coffee cup and a thermometer, in which energy charges in a reaction are observed via the change in temperature of the solution in the cup. The idea behind calorimeters is that if they are sufficiently insulated from the outside environment, any energy gained or lost in the chemical reaction will be directly observable as a temperature and/or pressure change in the calorimeter. In the following experiment a coffee-cup calorimeter containing 100 mL of H_2 O is used. The initial temperature of the calorimeter is 23.0 degree C. If 4.30 g of CaCl_2 is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The heal of solution delta H_soln of CaCl_2 is -82.8 kJ/mol. Express your answer with the appropriate units.

Explanation / Answer

Since Heat of solution = -82.8 KJ/mol

Heat for 4.30 g of CaCl2 will be

q = 82.8 x (4.30 / molar mass of CaCl2)

= 82.8 x ( 4.30 / 111)

= 3208 KJ

Now heat absorbed / released from calorimetry = m . c. t

where m is mass in grams

c is specific heat of water

and t is change in temperature

3208 = 100 x 4.184 x t

t = 7.166

So the final temperature will be 23 + 7.166 = 30oC

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