High School Students’ Conceptions about Energy in Chemical Reactions (focusing only in exothermic and endothermic reactions). Aim The aim of this study is to investigate students’ understanding of the energy concept in chemical reactions particularly in endothermic-exothermic reactions. Both qualitative and quantitative methodology was used for this investigation. A twenty-item multiple choice test was developed about the topic to measure the students’ understandings. This concept test was
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Chapter 1 Chemical Reactions and Equations Q.1. Why should magnesium ribbon be cleaned before burning in air ? Ans: Magnesium ribbon is a very reactive metal. When stored it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide being a stable compound prevents further reaction of magnesium with oxygen. The magnesium is cleaned before burning in air to remove this layer so that the metal can be exposed to air properly. Q.2. Write the balanced
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metals arranged in order of their reactivity based on displacement reactions‚ reduction of their oxides by hydrogen or carbon‚ the relative ease of decomposition of their compounds and reactions with oxygen‚ dilute acids and water. The higher up a metal is in the reactivity series‚ the more reactive it is. In the experiment conducted‚ the three metals‚ magnesium‚ zinc and copper each had to undergo displacement reactions and reactions with water‚ oxygen and dilute acids‚ to arrange them in the order
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Title Experiment 17 Reaction Kinetics- Determination of the Activation Energy of the Reaction Between Oxalic Acid and Potassium Permanganate. Objective To determine the activation energy of the reaction between oxalic acid and potassium permanganate. Theory and Background Activation energy is the minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport. In terms of the transition-state
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Coupled Reactions Louella Rose E. Tan‚ Frances May L. Coralde Institute of Chemistry‚ University of the Philippines‚ Diliman‚ Quezon City 1101 Philippines Results and Discussion A combustion reaction is a reaction that liberates heat and light. Magnesium is a stable element and reacts violently with evolution of much heat and light. The reason the magnesium burned in carbon dioxide was because it combined with the oxygen in the CO2 leaving elemental carbon behind. CO2(g) C(S) + O2(g)
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Redox reactions (Redox terminology‚ galvanic cells‚ standard electrode potentials‚ strength of oxidizing/reducing agents‚ corrosion and protection against it) Oxidation is defined as the loss of electrons and reduction is defined as the gain of electrons. Oxidizing agents‚ such as oxygen are defined as substances which accept electrons; reducing agents are substances which donate electrons. Redox reactions are: a) The reactions of metals with non-metals 2Na+Cl2→2Na+Cl- b) The reactions
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REACTIONS OF HYDROCARBONS Vanessa P. Manibpel De La Salle University - Dasmariñas ABSTRACT Five substances namely Hexane‚ Eugenol‚ Unknown hydrocarbon 1‚ Unknown hydrocarbon 2‚ and Acetylene gas was used for the selective reactivity of hydrocarbons to functional group tests; Bayer’s test‚ Bromine test light‚ Bromine test dark‚ and Tollen’s test. In Bayer’s test‚ only Acetylene‚ Eugenol and Unknown hydrocarbon 2 reacted positively and the rest retain the purplish color of KMnO4. On the other hand
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Redox Reactions Reactions involving oxidation and reduction processes are very important in our everyday world. They make batteries work and cause metals to corrode (or help to prevent their corrosion). They enable us to obtain heat by burning fuels--in factories and in our bodies. Many redox reactions are complex. However‚ combustion and synthesis (from elements) are two ordinary examples which require very little description. Just a little more involved are the displacement reactions‚ with
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Chemical Reactions What is a Chemical Reaction? Types of Chemical Reactions Redox Reactions Nonredox Reactions Classifying Reactions What is a Chemical Reaction? A chemical reaction is a process in which the identity of at least one substance changes. A chemical equation represents the total chemical change that occurs in a chemical reaction using symbols and chemical formulas for the substances involved. Reactants are the substances that are changed and products are the substances that are
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Chemical Reactions Chemical reactions happen in almost everything around us. Reactions are very important in everyday life‚ and science. Chemical reactions are the changing of substances to other substances by the breaking of bonds in reactants and the formation of new bonds in products. There are different types of chemical reactions such as combination reaction‚ decomposition reaction‚ single-replacement reaction‚ double-replacement reaction‚ and combustion reaction. Combination
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