(show all your works from part a to part f and please don\'t skip any questions
ID: 1014150 • Letter: #
Question
(show all your works from part a to part f and please don't skip any questions. Thanks you)
a. what is calorimetry and what is a calorimeter?
b. when a 15.5g sample of potassium chlorate dissolves in 100.0g of water in a calorimeter, the temperature of the water/solution drops from 20 degree celsius to 13.7 degree celsius. Write the balanced equation for this solution process
c. calculate the enthalpy change(in kJ/mol) for the solution process of part b(assuming the specific heat of the solution is essentially the same as the solvent)
d. is the process endothermic or exothermic
e. what is the amount of heat change of the salt(system)
f. what is the the amount of heat change for the solvent(surroundings)
Explanation / Answer
a. measurement of the amount of heat exchanged is called Calorimetry .
an apparatus used for measuring the amount of heat exchanged is called calorimeter.
b. KClO3(s) + H2O(l) ----> K^+(aq) + ClO3^-(aq)
c. heat changed = m*s*DT
= (100+15.5)*4.18*(20-13.7)
= 3.04 kj
No of mol of KClO3 = 15.5/122.55 = 0.126 mol
heat changed = 3.04/0.126 = 24.127 kj/mol
d. as the temperature decreases, it is endothermic process
e. heat change of the salt = 15.5*4.18*(20-13.7) = 0.408 kj
f. heat change of the solvent = 100*4.18*(20-13.7) = 0.263 kj
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