ENDOTHERMIC AND EXOTHERMIC EXPERIMENT NO. 5 GROUP NO. 2 LEADER: TARA FAYE BAYAS MEMBERS: ANN MARJORY V. CARIÑO PEARLY RUBY CARIAGA KRISTINE GRACE CORTEZ JULIUS BRYAN CRUZ ENDOTHERMIC AND EXOTHERMIC REACTION INTRODUCTION Chemical reaction may proceed with a net absorption of energy or with a net release of heat. The energy transaction may include heat, light or electricity. The term ‘endothermic’ and ‘exothermic’ refer to the heat exchange only. ENDOTHERMIC REACTION The word endothermic ("within-heating") describes a process or reaction in which the system absorbs energy from the surroundings in the form of heat. Its etymology stems from the prefix endo(derived from the Greek word ένδον, endon, "within") and the Greek word thermasi, (meaning “to heat”). The opposite of an endothermic process is an exothermic process, one that releases energy in the form of heat. The term endothermic was coined by Marcellin Berthelot. Expressed in a Chemical Equation: Energy + Reactants → Products The reactants have less potential energy than reactants. Energy must be input in order to raise the particles up to the higher energy level. EXAMPLE OF ENDOTHERMIC REACTION Photosynthesis is an example of an endothermic reaction. The chlorophyll and pigments in the plant absorb the light energy from the sun's rays, as endothermic reaction is that in which energy is absorbed. EXOTHERMIC REACTION Exothermic is a chemical reaction that releases energy in the form of light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation: reactants → products + energy The reactants have more potential energy than the products have. The extra energy is released to the surrounding. EXAMPLE OF EXOTHERMIC REACTION Explosions are examples of exothermic reactions as they release energy to their surroundings. Objective To determine the energy changes that occur during a certain type of chemical reaction Balance Beaker, 50 mL Graduated Cylinder, 50 mL Styrofoam cup/calorimeter Temperature Weighing paper REAGENTS Baking Soda(NaHCO3) 1.5 M Citric acid (H3C6H507) 2 M HCL Magnesium ribbon Part 2 A. Reacting Citric Acid and Baking Soda 1. Part II Place a 150 mL- beaker into the calorimeter as shown in the diagram. Put 30 mL of 1.5 M citric acid into the beaker. Place the temperature sensor into the citric acid solution. Click on “REC” button to begin data recording. Weigh out 10.0g of baking soda on a piece of weighing paper. After about 20 seconds have elapsed, add the baking soda to the citric acid solution. Gently stir the mixture to ensure complete reaction substances. Allow the computer to record data until a minimum temperature has been reached and temperature readings begin to increase or let the computer automatically end it after 250 seconds. Dispose the reaction products and rinse the cup. Reacting Magnesium and Hydrochloric Acid Repeat Procedure A using magnesium ribbon ( 5 cm long) instead of baking soda and hydrochloric acid in place of citric acid 1.5 M. HCL + Mg ribbon Run no.2 Citric acid + Baking Soda Run no. 1 Final Temp. 20 Initial Temp. 30 Temp. Change 10 C Final Temp. 30 Initial Temp 25 Temp. Change -5 Data from: Gr. 4 1. What type of energy change is associated with the chemical reaction between Citric Acid and Baking Soda? -chemical change .Endothermic Reaction With magnesium and Hydrochloric Acid -Heat energy. Exothermic Reaction 2. How do the experimental data support the energy changes described? -Through the heat that we applied , some of the chemicals that we mixed 3.What does a negative T value indicates? - it indicates into a colder region and it means that the temperature goes down. Therefore the endothermic reaction took place. 4.Described 3 ways to determine that chemical reaction has taken place. - when the experiment has taken place. The experimental take reaction/ then it bring into a natural reaction Change in color Change in odor Change in temperature Release of gas 5. Which reaction took place at a greater rate? Explain. The Exothermic Reaction ( Magnesium Ribbon and the Hydrochloric Acid ). - Shows higher temperature .