Oxygen compounds elemental analysis

J.9 You are asked to identify compound X, which was extracted from a plant seized by customs inspectors. You run a number of tests and collect the following data. Compound X is a white, crystalline solid. An aqueous solution of X turns litmus red and conducts electricity poorly, even when X is present at appreciable concentrations. When you add sodium hydroxide to the solution a reaction takes place. A solution of the products of the reaction conducts electricity well. An elemental analysis of X shows that the mass percentage composition of the compound is 26.68% C and 2.239% H, with the remainder being oxygen. A mass spectrum of X yields a molar mass of 90.0 g-moF. (a) Write the empirical formula of X. (b) Write... 

Because each chemical element is conserved, the masses of the products are equal to the masses of the elements contained in the original compound. This lets us complete the elemental analysis of the compound. The 5.00-g sample contained 4.63 g mercury and 0.37 g oxygen. The percent composition is found by dividing each elemental mass by the total mass and multiplying by 100 ... 

Widespread medicinal use of colloidal bismuth subcitrate (CBS) has prompted extensive studies of bismuth compounds involving the citrate anion. Bismuth citrate is essentially insoluble in water, but a dramatic increase in solubility with increasing pH has been exploited as a bio-ready source of soluble bismuth, a material referred to as CBS. Formulation of these solutions is complicated by the variability of the bismuth anion stoichiometry, the presence of potassium and/ or ammonium cations, the susceptibility of bismuth to oxygenation to Bi=0, and the incorporation of water in isolated solids. Consequently, a variety of formulas are classified in the literature as CBS. Solids isolated from various, often ill-defined combinations of bismuth citrate, citric acid, potassium hydroxide, or ammonium hydroxide have been assigned formulas on the basis of elemental analysis data or by determination of water and ammonia content, but are of low significance in the absence of complementary data other than thermal analysis (163), infrared spectroscopy (163), or NMR spectroscopy (164). In this context, the Merck index lists the chemical formula of CBS as KgfNHJaBieOafOHMCeHsCbh in the 11th edition (165), but in the most recent edition provides a less precise name, tripotassium dicitrato bismuthate (166). 

A highly toxic gas that has been used in chemical warfare gives the following elemental analysis figures 12.1% carbon, 16.2% oxygen, and 71.7% chlorine by mass. Its molar mass is 98.9 g-moU1. Write the Lewis structure of this compound. 

Highly selective to halogenated and oxygenated compounds Electron capture detector EDB, DBCP (EPA 8011) Acrylamide (EPA 8032) Phenols (EPA 8041) Phthalates (EPA 8061) Organochlorine pesticides (EPA 8081) PCBs (EPA 8082) Nitroaromatics and cyclic ketones (EPA 8091) Haloethers (EPA 8111) Chlorinated herbicides (EPA 8151) CLP SOW for organic analysis Interferences from Elemental sulfur (S8) Waxes, lipids, other high molecular weight compounds Phthalate esters, which are common laboratory contaminants Oil in PCB analysis... 

Calculation of the Empirical Formula Molecular formulas can be determined by a two-step process. The first step is the determination of an empirical formula, simply the relative ratios of the elements present. Suppose, for example, that an unknown compound was found by quantitative elemental analysis to contain 40.0% carbon and 6.67% hydrogen. The remainder of the weight (53.3%) is assumed to be oxygen. To convert these numbers to an empirical formula, we can follow a simple procedure. 

When BHT and other similar phenols were first prepared in the 1940s, chemists were not sure of their structures. The chemical formulae could be determined by elemental analysis, but NMR. which would have instantly revealed the structure, had not yet been discovered. The problem arose because the compound exhibited none of the normal reactions or tests for phenols for example, it was not soluble in alkali. The chemists thought the second t-butyl group had added to oxygen to make an ether. BHT does not behave like other phenols because the -OH group is hindered by the two large t-butyl groups. 

Alkoxides. Exposure of the pentavalent alkoxide complex U(OCH2CH3)5 to oxygen was first reported to produce a small amount of a volatile and thermally unstable red liquid byproduct. Elemental analysis of the compound was consistent with the stoichiometry U(0CH2CH3)6, and molecular weight determinations suggested a monomeric structure in benzene. Improved yields of U(OCH2CH3)fs have been achieved using other reaction routes (see Equations (45) to (47)) ... 

Problem 2.5 Only carbon and hydrogen were detected by a qualitative elemental analysis of the compound ethyl alcohol quantitative analysis gave 52.1% carbon and 13.1% hydrogen, (a) Why would it be assumed that ethyl alcohol contains oxygen (b) What percentage of oxygen would be assumed ... 

Oxygen (O, at. mass 16.00) is a gas, O2 (O3 in ozone). It occurs in most compounds in the -II oxidation state, and in the -I state in peroxides. With other elements, it forms numerous oxide complexes such as Cr04 , M0O4, VO, U02, S04 , NOi . Volatile oxides include OSO4 and CO2. Oxygen compounds of great importance in analysis are hydrogen peroxide and the peroxide complexes of a number of metals, e.g., Ti, V, Nb, U, and Zr. 

Elemental analysis is the process for determining the partial or complete chemical formula for a substance. Most commonly, it involves the complete combustion in air or oxygen of the substance and then quantitating the amount of elemental oxides produced. In the case of organic compounds, the carbon is converted to carbon dioxide and the hydrogen to water. From these, the percent carbon and percent hydrogen in the substance can be found and compared with a proposed chemical formula for the substance at hand. 

Oxygen and nitrogen, for example, unite with each other to form no less than five compounds. Upon analysis we find that in these the two elements bear to each other the following relations by weight ... 

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