Example 1: urea, (nh2)2co, is used in the manufacture of resins and glues. when 5.00 g of urea is dissolved in 250.0 ml of water
(d = 1.00 g/ml) at 30.0 c, 27.6 kj of heat is absorbed. (specific heat of water 4.18 j/g.c) is the solution process exothermic? what is ? what is the final temperature of solution?
A) i believe the reaction is exothermic, because 27.6 kg of thermal energy is gained by the water solution, the dissolution of urea is exothermic. Exothermic reaction is a chemical reaction that releases energy by light or heat. It is the opposite of an endothermic reaction where heat is gained by the reaction.
b) The water gained the heat released when urea dissolve. That is the water gained 27.6 kJ, while dissolution of urea released 27.6 kJ. Therefore, the heat gained is equal to the heat lost.
c) From part B, since heat gained is equal to heal lost, then 250 g × (Tf -30) ×4.18 J/g = 27600 J = 1045 Tf - 31350J = 27600 J Tf = 56.41°C. Therefore the final temperature of the solution is 56.41°C
d) The initial and final temperature in Fahrenheit °F = °C × (9/5) +32, Thus, 30°C will be equal to 86° F while 56.41 will be equivalent to 133.54 ° F
