Abstract. The laboratory work performed was undertaken to explore the multiplicity and possibilities of chemical reactions. During the course of the work, combination, decomposition, single and double displacement, and rearrangement reactions were performed. Mixed type reactions of different types were also performed. Qualitative signs and evidences of chemical reactions that take place in the mixture of reactants, were examined during the course of the work.
Different types of reactions regarding change of energy were studied. As a result of laboratory work, skills for performing basic types of chemical reactions and using simple chemical accessories and glassware were obtained. Introduction. Chemical reaction – an interaction between substances that results in formation of new substances that were not in the mixture initially, or in change of existing substances. Reactant – a starting substance that enters chemical reaction.
Product – a final substance that is formed during the reaction. Catalyst – a substance that facilitates a chemical reaction without being consumed itself. Combination – a reaction that results in formation of a composite product from more simple reagents. Decomposition – a reaction that results in disintegration of a composite reagent onto more simple products. Displacement – a reaction that is results in substitution of a chemical group of a composite reagent by another chemical group.
Rearrangement – a reaction that changes order of atoms in a reactant without changing the set of the atoms in that reactant. Exothermic – a reaction that is accompanied with emission of energy. Endothermic – a reaction that is accompanied with absorption of energy. Data Sheet. During the experiments performed no measures were performed, except for measuring the reagents that were required for certain experimental reactions.
During the reactions were observed qualitative changes of reaction mixtures and substances as following: production of white powdered ash of magnesium oxide in reaction of magnesium combustion; formation of carbon out of cellulose (appearance of black color) under influence of sulfuric acid and heating; change of color of blue vitriol from blue to white because of dehydration and back to blue as a result of rehydration of anhydrous copper (II) sulfate; formation of crystals on the copper wire and changes of color of silver (I) nitrate solution from colorless clear to very light blue; change of transparency of calcium chloride solution and sodium carbonate solution into cloudy white liquid after mixing these solutions; formation of white solid structures in previously clear and yellow solution of proteins after hydrochloric acid solution was added; appearance and disappearance of pink color as result of phenolphthalein interactions with ammonium hydroxide and gaseous mixture of carbon dioxide and water; change of color of copper coin to silvery and then to gold color. Limits on Results. Instruments used in the work experiments are: crucible tongs.
Bunsen flame, beaker, graduate cylinder, evaporating dish, filter paper, test tube, hot plate, scopula and wooden splint. All of these, excluding beaker and graduate cylinder, are simple instruments that are not intended to perform measures, and hence ungraduated. 50 ml, 150 ml and 250 ml beakers used in several experiments have standard error about ± 0,1 ml. 10 ml graduate cylinder has standard error about 0,05 ml. Conclusion.
Substances can enter chemical reactions and change during the course of these reactions. New substances can form and existing can change as a result of chemical reaction. Formation of gas or solid in liquid reaction mixtures, changes of color and transparency of solutions, dissolving or formation of solid precipitates can occur, and these are the signs of chemical reactions. Many reactions are accompanied by these signs, but some have no visible evidence of chemical reaction that took place. Some reactions are accompanied with energy emission, some others require external energy to proceed.
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