A student heats 62.33 grams of chromium to 99.36 °C and then drops it into a cup containing 82.16 grams of water at 21.67 °C. She measures the final temperature to be 27.31 °C. The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.87 J/°C. Assuming that no heat is lost to the surroundings calculate the specific heat of chromium.
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.
| In the laboratory a "coffee cup" calorimeter, or constant pressure calorimeter, is frequently used to determine the specific heat of a solid, or to measure the energy of a solution phase reaction. A student heats 62.33 grams of chromium to 99.36 °C and then drops it into a cup containing 82.16 grams of water at 21.67 °C. She measures the final temperature to be 27.31 °C. The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.87 J/°C. Assuming that no heat is lost to the surroundings calculate the specific heat of chromium. Specific Heat (Cr) = _______J/g°C. |
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