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NAME : THAMARAI A/P RAJENDRAN ID NUMBER: 09ALB07214 LABORATORY 1A : ATOMIC STRUCTURE BONDING AND PERIODICITY COURSE: BIOTECHNOLOGY (Y 1 S 1) EXPERIMENT 3: STOICHIOMETRY REACTION TITLE: Stoichiometry Reaction. OBJECTIVES OF EXPERIMENT: The objective of this experiment is to decompose sodium hydrogen carbonate(sodium bicarbonate) by heating, and to accurately measure the degree of completion of the reaction by analyzing the solid sodium carbonate product. THEORY AND BACKGROUND: We need to know how much product we will get from a given amount of reactant and we also need to know how much heat a given reaction produces in order to be able to safely perform the reaction. When we measure chemical or physical quantities of starting materials or products, these are a function of the molecular transformations involved in the reaction. That is, the reaction stoichiometry (whether a molecule of compound X reacts with 1 or 2 molecules of Y) must be involved in any calculation about amounts of reactants or products. However, in the laboratory, we must be concerned with far larger quantities than the molecular scale. Similarly, going in the reverse direction, we must be able to relate the amount of heat evolved in a laboratory scale reaction to that involved when two molecules react. ...read more.


The concentration of the standardized HCl was recorded to 4 decimals. 6. Three 250conical flasks were rinsed out with distilled water and 25.00 aliquots of the Na2CO3 solution was pipetted into each. 7. Two or three drops of thymol blue indicator were added to each flask and the Na2CO3 solution was titrated with the HCl until the end point was reached (a grey-green color). The HCl was added drop-wise towards the end of titration. 8. The volume to the nearest 0.5 was read off; the titration was repeated with the other Na2CO3 aliquots. The readings were recorded in a table. The reading should be consistent to within 0.10. If not, the process was repeated until consistency has been obtained. DATA/RESULTS: Mass of the empty test tube: 30.4472g Mass of NaHCO3 + test tube: 33.1272g Mass of NaHCO3: 33.1272g - 30.4472g = 2.6800g Mass of NaHCO3 after the thermal decomposition + test tube: 32.1275g Mass of Na2CO3 + any unheated NaHCO3: 32.1275g - 30.4472g = 1.6803g Initial volume of HCl solution in burette (ml) Final volume of HCl solution in burette (ml) Volume of HCl solution used (ml) First flask 0.0 33.2 33.2 Second flask 0.0 33.3 33.3 Third flask 0.0 33.2 33.2 Table 1 DISCUSSION: An indicator is a solution that changes the color of the reacting solution as because it reacts with an acid or a base. ...read more.


by a whole number. When an equation is multiplied by a constant, its ?H must be multiplied by the same number as well. If an equation is reversed, ?H for the reaction must also be reversed (eg. -?H). Hess's Law says that enthalpy changes are additive. Thus the ?H for a single reaction can be calculated from the difference between the heats of formation of the products minus the heat of formation of the reactants. CONCLUSION: Stoichiometry rests upon the law of conservation of mass, the law of definite proportions (i.e., the law of constant composition) and the law of multiple proportions. Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitative (measurable) relationships of the reactants and products in a balanced chemical reaction (chemicals). It can be used to calculate quantities such as the amount of products that can be produced with the given reactants and percent yield. In general, chemical reactions combine in definite ratios of chemicals. Since chemical reactions can neither create nor destroy matter, nor transmute one element into another, the amount of each element must be the same throughout the overall reaction. For example, the amount of elements x on the reactant side must equal the amount of element X on the product side. Reaction stoichiometry allows us to determine the amount of substance that is consumed or produced by a reaction. ...read more.

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