A student wishes to determine the heat capacity of a coffee-cup calorimeter. After she mixes 107.5 g of water at 62.7°C with 107.5 g of water, already in the calorimeter, at 20.9°C, the final temperature of the water is 35.0°C. Calculate the heat capacity of the calorimeter in J/K. Use 4.184 J/g°C as the specific heat of water. Enter a number to 1 decimal place.
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
Heat capacity of a calorimeter is the amount of heat energy absorbed by the calorimeter per Kelvin raise in temperature.
Heat capacity is an extensive property. It depends upon amount of substance present.
Given that,
Mass of water present initially in calorimeter = 107.5 g
Initial temperature of water in calorimeter =
Mass of water added = 107.5 g
Initial temperature of water added =
Final temperature of total water =
Water added to the calorimeter is initially at higher temperature and is cooled to a lower temperature. So, heat energy is lost by this system.
Water initially present in calorimeter has raised in temperature. So, heat energy is gained by this system.
By substracting the amount of heat gained by the system from the amount of heat lost by the system, the amount of heat energy lost to calorimeter is determined.
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