STAWA Investigation 35: Exothermic and Endothermic Processes

Topics: Energy, Chemical reaction, Thermodynamics Pages: 3 (960 words) Published: August 11, 2015
Introduction, aim and hypothesis
Chemical reactions are accompanied by the release or absorption of energy. Reactions which release energy are described as exothermic and those which absorb energy are endothermic. The energy released in chemical reactions was previously stored as chemical potential energy in the reactants; this stored energy is called enthalpy. The aim of this practical is to observe and classify chemical processes as endothermic or exothermic, based on the changes in temperature measured and the observations made. If a chemical reaction produces products with more chemical potential energy than the reactants, then the reaction is endothermic; if the chemical potential energy present after the reaction occurs is lower than the chemical potential energy that was present in the reactants, then the reaction is endothermic. This change in chemical potential energy will be observed and measured based on the change in temperature of the reaction. Due to my lack of prior knowledge in this situation, I cannot form a more specific hypothesis as to which reactants with behave in what way. The tasks

A. Solution Processes
B. Ammonium Chloride and Barium Hydroxide
C. Iron and Copper(II) Sulfate
Part A Solution Processes
Equipment (As given in STAWA Exploring Chemistry Year 11; Organic Chemistry; Investigation 35 [page 86]) Procedures (In book)
Results (Temperatures)
Solute
Initial Temp. (°C)
Final Temp. (°C)
Endothermic/ Exothermic
Sodium Hydroxide NaOH
16.5
19.8
Exothermic
Ammonium Chloride NH4Cl

15.5
Endothermic
Sodium Acetate NaCH3COO

16.2
Slightly endothermic
Sodium Chloride NaCl

16.5
Neither

Part B Ammonium Chloride and Barium Hydroxide
Equipment and procedures (In book)
Results (observations)
A white solid forms in the bottom of the test tube after vigorous shaking; the lowest temperature recorded was 9°C. Part C Iron and Copper(II) Sulfate
Equipment and procedures (In book)
Results (observations)
The blue...


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