Exothermic Endothermic amp chemical change A Lab Investigation

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Students will have an easier time devising a fair test if they are well versed in the definitions of. physical changes and chemical changes Students should propose an experiment to you before. they test their hypothesis To observe a temperature change during a physical change students. should devise a procedure such as, Add 10 mL of water to a small plastic cup and place a thermometer in the water Record the. initial temperature Ti, Add teaspoon of calcium chloride to the water and swirl the cup After it has stopped. changing record the final temperature Tf,Pre Lab Discussion. This investigation introduces the concepts of enthalpy heat of H in the context of exother. mic and endothermic reactions To give students a deeper grounding in the basics and reinforce. basic concepts covered previously you may wish to review the mechanics of chemical changes. how to write balanced chemical equations and the law of conservation of energy. Incorporating into the Curriculum, This investigation could be incorporated into a unit on chemical changes or thermochemistry. 2013 American Chemical Society Energy Foundations for High School Chemistry 89. Teacher s key,Analyzing Evidence, Please note that initial and final temperature readings may vary slightly from student to student.
The baking soda and vinegar reaction should produce a termpature decrease of approximately. 7 C The baking soda and calcium chloride reaction should produce a temperature increase of. approximately 15 20 C,Exothermic or,Process Ti Tf T H. endothermic,Baking soda vinegar 22 C 15 C 7 C Endothermic. Baking soda solution,22 C 42 C 20 C Exothermic,calcium chloride. 1 Based on your observations of the baking soda and vinegar reaction is the reaction exo. thermic or endothermic Apply your knowledge of energy changes in chemical reactions. to complete the table above,Endothermic see table above. 2 Based on your observations of the baking soda solution and calcium chloride reaction. is this chemical reaction exothermic or endothermic Apply your knowledge of energy. changes in chemical reactions to complete the table above. Exothermic see table above,Interpreting Evidence, 1 In the chemical reaction between baking soda and vinegar what did you observe other.
than a temperature change What might this tell you about one of the products of this. chemical change, The reaction mixture bubbled so one of the products must have been a gas By considering the. reactants students may be able to infer that carbon dioxide was produced. 2 In the chemical reaction between baking soda solution and calcium chloride what did. you observe other than a temperature change What might this tell you about one of the. products of this chemical change, The reaction mixture bubbled so one of the products must have been a gas By considering the. reactants students may be able to infer that carbon dioxide was produced. 2013 American Chemical Society Energy Foundations for High School Chemistry 95. 3 Write the chemical equation for, the chemical reaction between baking soda and vinegar. C2H4O2 NaHCO3 CO2 H2O NaC2H3O2, the chemical reaction between baking soda and calcium chloride. 2NaHCO3 CaCl2 2NaCl CaCO3 H2O CO2, 4 Using the language of breaking and making bonds explain the net energy change for the.
chemical reaction between baking soda and calcium chloride. In the chemical reaction between baking soda and calcium chloride more energy is released. when the products 2NaCl CaCO3 H2O CO2 are formed than energy was used to break. bonds in the reactants 2NaHCO3 CaCl2 There is therefore a net release of energy to the. surroundings and the reaction is exothermic, 5 Draw energy profiles for both chemical reactions Are they the same or different. Baking soda vinegar,Endothermic,CO2 H2O NaC2H3O2,C2H4O2 NaHCO3. 96 Energy Foundations for High School Chemistry 2013 American Chemical Society. Baking soda calcium chloride,Exothermic,2NaHCO3 CaCl2. 6 What is the sign of the enthalpy of reaction H for an exothermic reaction Why. The enthalpy heat for an exothermic reaction must be negative because more energy is released. when the products are formed than is used when the reactants are broken up. 2013 American Chemical Society Energy Foundations for High School Chemistry 97. Reflecting on the Investigation, Students should propose an experiment to you before they test their hypothesis To observe a. temperature change during a physical change students should devise a procedure such as. 1 Based on your investigation so far do you think that energy changes only accompany. chemical reactions Using only the materials from the first two reactions design an. experiment that would test this idea Propose a procedure and have it approved by your. teacher before you continue experimenting, Students should suggest a procedure like the following.
Exothermic, Add 10 mL of water to a small plastic cup and place a thermometer in the water. Record the initial temperature Ti, Add teaspoon of calcium chloride to the water and swirl the cup After it has. stopped changing record the final temperature Tf,Endothermic. Add 10 mL of water to a small plastic cup and place a thermometer in the water. Record the initial temperature Ti, Add teaspoon of sodium bicarbonate to the water and swirl the cup After it has. stopped changing record the final temperature Tf, 2 Based on the experiment you conducted in the question above do you think dissolving is.
a chemical change Explain your reasoning, Student answers will vary Some students may argue that nothing chemically distinct is made. so dissolving is a physical change Other students may see the disruption of intermolecular forces. as bond breaking and solvating ions as bond making and therefore regard dissolving as a. chemical change, 3 Using the language of breaking and making bonds how can you describe the temperature. change you observed when you dissolved calcium chloride in water. More energy was released when the calcium and chloride ions were combined with water than. was required to break them apart, 4 How might you use exothermic or endothermic processes to solve a real world problem. Are there any instances when it would be useful to quickly make something hot or cold. Explain how it is useful to know which processes absorb or release energy. Exothermic reactions could be harnessed to power machines or heat homes while endothermic. reactions could be used for treating injuries or cooling By classifying reactions as exothermic or. endothermic we understand which reactions are best suited to meet specific challenges. 98 Energy Foundations for High School Chemistry 2013 American Chemical Society. Endothermic Add 10 mL of water to a small plastic cup and place a thermometer in the water Record the initial temperature T i Add teaspoon of sodium bicarbonate to the water and swirl the cup After it has stopped changing record the final temperature T f 2 Based on the experiment you conducted in the question above do you think dissolving is a chemical change Explain

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