Title : Determination of the Valency of Magnesium Objective: . To determine the stoichiometry of the magnesium 2. To study the quantitative relations between amounts of reactants and products of the reaction. Theory & Background : Stoichiometry is the study of the combination of elements in chemical reactions. Stoichiometry refers to the relative number of atoms of various elements found in a chemical substance and is often useful in characterizing a chemical reaction. The related term stoichiometric is often used in thermodynamics to refer to the "perfect mixture" of a fuel and air. Stoichiometry is often used to balance chemical equations. In this experimet, a known starting mass of magnesium and the measured collection of hydrogen gas will be used to determine the reaction stoichiometry. Stoichiometry rests upon the law of conservation of mass, the law of definite proportions and the law of multiple proportions. 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. This experiment determines the stoichiometry of a reaction of magnesium and hydrochloric acid(HCl). The relationship between moles of magnesium reacted and moles of hydrogen produced are plotted.
A 0.60 um film of silicon dioxide is to be etched with a buffered oxide etchant of etch rate 750 A min-1. Process data shows that the thickness may vary up to 10% and the etch rate may vary up to 15%.
Andy Somody 97300-6222 ENSC 495 Assignment #3 6-1). a). A 0.60 um film of silicon dioxide is to be etched with a buffered oxide etchant of etch rate 750 A min-1. Process data shows that the thickness may vary up to 10% and the etch rate may vary up to 15%. The maximum possible thickness of the silicon dioxide film is therefore 110% of its nominal value. Therefore, the maximum possible thickness of the silicon dioxide film can be determined through the following calculation: where zmax is the maximum possible thickness of the silicon dioxide film and znominal is the nominal thickness of the silicon dioxide film. Therefore, znominal = 0.60 um. Any number expressed as a percentage can alternatively be expressed as a decimal. For example, 110% can be expressed as 1.1. Using this decimal format, the above formula can be rewritten in the following manner: Substituting our previously determined value for znominal into the above formula yields: with significant figures applied Similarly, the minimum possible etch rate of the buffered oxide etchant is 85% of its nominal value. Therefore, the minimum possible etch rate of the buffered oxide etchant can be determined through the following calculation: where rmin is the minimum possible etch rate of the buffered oxide etchant and rnominal is the minimum possible etch rate of the buffered oxide etchant. Therefore, rnominal =
Title: Chemical Preservatives .Calcium disodium EDTA It was found in "mayonnaise". Properties It is the salt of ethylene diamine tetraacetic acid (EDTA). Utilization It is applied as a chelating agent. Its function is to control the reaction of metal ions with some organic and inorganic components that will result in deterioration of foods. Apart from that, the preservative also acts as antioxidant antimicrobial agent, especially against gram-negative bacteria. Mechanisms of action Ca disodium EDTA blocks the normal reaction of metal ions by binding to their reactive sites. This increases its efficiency as an antioxidant. Consequently, the oxidation of ascorbic acid and fat-soluble vitamins is hindered and also the rancidity of the product. The resistance of gram-negative bacteria is overcome by the removal of lipopolysaccharide containing membrane. 2.Calcium Propionate (C6H10CaO4) It was found in " wholemeal bread rolls". Properties It is the salt of propionic acid. It is only soluble in water but insoluble in alcohol. Utilization The antimicrobial activity is particularly against mycotoxin forming moulds, less so against bacteria. No inhibition effect has been demonstrated against yeast. Therefore, it is mainly used for bread preservation, as it will not interrupt the leavening in
Experiment 3 Title: Stoichiometry Reaction Objectives: 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. Introduction: Stoichiometry is the calculation of quantitative (measurable) relationships of the reactants and products in a balanced chemical reaction. It can be used to calculate quantities such as the amount of products that can be produced with the given reactants and percent yield. Stoichiometry calculations are based on the fact that atoms are conserved. They cannot be destroyed or created. Numbers and types of atoms before and after the reactions are always the same. This is the basic law of nature. From the atomic and molecular point of view, the stoichiometry in a chemical reaction is very simple. However, atoms of different elements and molecules of different substances have different weights. We must be able to relate the amount of heat evolved in a laboratory scale reaction to that involved when two molecules react. The scaling factor used to relate readily useable quantities to the molecular scale is called the mole. 1 mole = 6.023 x 1023 molecules = Avogadro's number of molecules In this experiment, several reactions will be performed and physical measurements will be made that subsequently relate to the molecular
Describe The Concept Of Oxidation Levels And Discuss The Use Of Oxidising And Reducing Agents For The Modification Of Functional Groups In Organic Chemistry.
Describe The Concept Of Oxidation Levels And Discuss The Use Of Oxidising And Reducing Agents For The Modification Of Functional Groups In Organic Chemistry. The majority of the reactions of organic compounds, which involve conversion of one type to another, can be classified as oxidation or reduction. This conclusion can be justified on the basis of the definitions of the terms, oxidation and reduction. Oxidation is defined as a loss of electrons and reduction as a gain of electrons. Other definitions have been formulated which deal with such concepts as oxidation involving removal of hydrogen to form multiple bonds or to make new bonds between carbon and a more electronegative element, and reduction involving reactions in which carbon forms new bonds to hydrogen. It is harder to define oxidation as a loss of electrons in organic compounds compared with metals. In oxidation and reduction of metals, the electronic changes involve transfer, and thus a true net loss or gain of electrons. In covalently bonded compounds, such as the compounds of carbon, such electron transfers do not usually occur. Instead, the carbon atom, even though it retains a covalency of four, changed markedly in the degree of control it exerts over the covalently bound electrons. Thus, it may be that when the electron density about a carbon atom decreases, it has undergone oxidation, and conversely an
Calorimetry. The aim of the experiment is to determine the enthalpy change during a chemical reaction with the use of an improvised calorimeter.
Experiment 1: Calorimetry Efreihm Jovi T. de Guzman Kristiene B. Sadiwa Institute of Chemistry, University of the Philippines, Diliman, Quezon City 1101 Philippines Results and Discussion The aim of the experiment is to determine the enthalpy change during a chemical reaction with the use of an improvised calorimeter. The calorimeter was calibrated by allowing 10.0 mL NaOH to react with 5.00 mL HCl. In this reaction, ?T has been acquired and is used in the equation to determine the heat capacity of the calorimeter. qcal can also be determined using the formula in which m was calculated using stoichiometry and c is the specific heat of the product, water, which is equivalent to 4.18 Jg-1°C-1. qrxn can then be determined from qcal, given by the formula since the qsystem is equal to zero in an adiabatic system. After the calibration, ?T from different reaction systems have been measured to determine the ?Hrxn. The number of moles of the limiting reactant is determined and is used in the equation to calculate for heat of reaction. In reactions involving solids, the solid reactants or products may absorb the heat from the reaction. To account for that event, the following formula is used: After computing for ?Hrxn, the results show that all the reactions were exothermic. Percent error was calculated to determine whether the results were accurate or not. Percent
Analysis of an unknown base. In this experiment will we prepare a primary standard acid of KHP (potassium acid phthalate), which is a monoprotic acid, which means it only has one equivalence point. It was chosen because it has a fast reaction with most
Analytical Chemistry 2080 Experiment #2: Analysis of an unknown base. Name: Elizabeth Conway TA: Anna Date performed: Wednesday September 26th 2007 Date Due: Wednesday, October 3rd 2007 Unknown #: 176 Experiment #2: Analysis of an Unknown base. Introduction: In this experiment will we prepare a primary standard acid of KHP (potassium acid phthalate), which is a monoprotic acid, which means it only has one equivalence point. It was chosen because it has a fast reaction with most bases. When determining normality of a base, a standard acid solution (KHP) is used through the acid-base reaction: HA + B¯ › HB + A+ Since HB is a weaker acid then KHP in this case, the reaction goes quickly into completion, eventually achieving its end-point. The end-point is detected with phenolphthalein, an acid-base indicator. The end point is when the pKa is ideally the same as the pH, which means that the standard titrimetric equation of stoichiometry can be used to find the concentration of the unknown: Va * Na = Vb * Nb Where, Va is equal to the volume of the Standard KHP added to the unknown to reach the equivalence point, Na is equal to the Normality of the Standard KHP, Vb is equal to the volume of the unknown and Nb is the Normality of the unknown. The equivalence point is when the amount of KHP is added is equal to the amount of analyte present in to unknown
Spectrochemical Series of Some d-block Transition Metal Complexes. The spectrochemical series of the ligands for Cu(II), Co(II) and Cu(II) ions were constructed by visual inspection and spectral analysis of the transition metal complexes. Results show tha
Spectrochemical Series of Some d-block Transition Metal Complexes Jerick Imbao* Department of Chemistry, Ateneo de Manila University, Katipunan Avenue, Loyola Heights, Quezon City, Philippines Date Experiment Completed: July 5, 2011 Date Report Submitted: July 19, 2011 KEYWORDS: Spectrochemical series, Co, Ni, Cu, transition metals ABSTRACT: The spectrochemical series of the ligands for Cu(II), Co(II) and Cu(II) ions were constructed by visual inspection and spectral analysis of the transition metal complexes. Results show that ethylenediamine is the strongest ligand while the trend oxalate < pyridine < NH3 has been consistently observed. This agrees with the fact that nitrogen-donor ligands are stronger than oxygen-donor ligands. INTRODUCTION Having partially filled d orbitals, transition metals have a wide range of oxidation states and form coordination compounds that are relatively more stable than other metals and metalloids. All metallic and metalloid elements create coordination compounds but they are most stable among the transition elements.1 Coordination compounds are produced when groups of ions, atoms or molecules chemically bond with each other by accepting or donating pairs of electrons. Metal cations act as Lewis acids which accept electron while the groups that donate electron pairs are called ligands which act as Lewis bases.2 Interestingly,
Preface People usually ignore what is meant to be normal to them. This is the same as for food additives. We usually do not bother what is being added into our food as long as it is delicious. However, different food additives have different health effect on human health. This report is going to focus on food colouring and its impact on human health and its social importance. Table of Contents Page List of Figures and Tables 3 .0 Introduction 4 History of azo dyes 5 2.0 Chemical part of the topic 2.1 Coupling Reaction 5 2.2 The Molecular Structure of Azo Dyes 7 3.0 Advantages and Disadvantages of Azo Dye 3.1 The Application of Azo Dye 8 3.2 The Downside of Azo Dyes 9 4.0 Current development of azo dye around the world 4.1 Food Act 1983 (Act 281) & Regulations in Malaysia 11 4.2 Types of banned azo dyes in major industrialised countries 11 5.0 Conclusion 12 Bibliography 13 Appendix I 14 References List of Figures and Tables Page Figure 1: The History Development of Azo Dye 5 Figure 2.1.1: The products of reaction between (1) diazonium ion and phenol (2) diazonium ion and 2- naphthol 6 Table 2.1.2: Structures of Azo Dye and Its Properties 6 Figure 2.2.1: Tartrazine 7 Figure 2.2.2: Brilliant Black 7 Table 3.1.1: Use of
Determination Of The Concentration Of Acid In Gastric Juice Introduction: In this experiment, I will be able to carry out a technique known as titration. The experimental titration is used to find out how accurately how much a chemical substance is dissolved in a given volume of a solution, that is the concentration of the solution. The aim of this particular experiment is to revise the use of pipettes and burettes and titrations by the determination of the concentration of hydrochloric acid in an unknown solution and also reinforce the concept of molarity hence I will be using the method titration. This particular method is suitable for our aim because it will allow us to obtain results which enables us to determine the molarity of a solution of sodium hydroxide against our two separate standards. The equation I will be looking at is: NaOH(aq) + HCl(aq) › NaCl(aq) + H2O(l) Acid Base Salt Water The reaction is an acid-base reaction which involves the transfer of protons. Acid-base reactions are also known as neutralisation reacrions. The compound formed by the cation of the base and the anion of the salt. When using the indicator, phenolphthalein, the colour will change to light pink. A colour change will occur when the end-poit of a titration is e=reached. The reaction states that 1 molecule of NaOH to produce 1 molecule of salt, in this