Thermodynamics and Calorimetry: Understanding Heat, Energy, and Chemical Reactions, Exams of Chemistry

Download Thermodynamics and Calorimetry: Understanding Heat, Energy, and Chemical Reactions and more Exams Chemistry in PDF only on Docsity! Chem 103 Module 6 calorie (cal) - unit of heat or other energy; the amount of energy required to raise 1 gram of water by 1 degree Celsius; 1 cal is defined as 4.184 J endothermic process - chemical reaction or physical change that absorbs heat energy - the capacity to supply heat or do work exothermic process - chemical reaction or physical change that releases heat joule (J) - SI unit of energy; 1 joule is the kinetic energy of an object with a mass of 2kg moving with a velocity of 1 m/s, 1 J = 1 kg m2/s and 4.184 J = 1 cal kinetic energy - energy of a moving body, in joules, equal to 1/2mv^2 potential energy - energy of a particle or system of particles derived from relative position, composition, or condition thermal energy - kinetic energy associated with the random movement of atoms or molecules thermochemistry - study of measuring the amount of heat absorbed or released during a chemical reaction or a physical change which of the following substances would you expect to have a relatively high chemical potential energy: Wood, Gasoline, Chalk, Water, Hydrogen Gas? - Wood, gasoline, hydrogen gas heat (q) - transfer of thermal energy between two substances surroundings - all matter other than the system being studied system - portion of matter undergoing a chemical or physical change being studied temperature - intensive property of matter that is a quantitative measure of "hotness" and "coldness" When 50.0 mL of 0.10 M HCl(aq) and 50.0 mL of 0.10 M NaOH(aq), both at 22.0 °C, are added to a coffee cup calorimeter, the temperature of the mixture reaches a maximum of 28.9 °C degrees. Would the amount of heat measured for this reaction be greater, lesser, or remain the same if we used a calorimeter that was a poorer insulator than a coffee cup calorimeter? Explain your answer - Lesser; more heat would be lost to the coffee cup and the environment and so ΔT for the water would be lesser and the calculated q would be lesser When solid ammonium nitrate dissolves in water, the solution becomes cold. This is the basis for an "instant ice pack". When 3.21 g of solid NH4NO3 dissolves in 50.0 g of water at 24.9 °C in a calorimeter, the temperature decreases to 20.3 °C. Would the amount of heat absorbed by the dissolution appear greater, lesser, or remain the same if the experimenter used a calorimeter that was a poorer insulator than a coffee cup calorimeter? Explain your answer. -