Werner Complexes - Preparation and Determination of Structural Formula
Werner Complexes - Preparation and Determination of Structural Formula Abstract: In this experiment three Werner complexes, hexaamminecobalt(III) chloride, pentaamminechlorocobalt(III) chloride and hexaamminenickel(II) chloride were synthesized so their structural formula could be examined through magnetic susceptibility, electronic conductance measurements and the analysis of free chloride in the two cobalt complexes through titrations of silver nitrate. Cobalt (III) coordination compounds usually only form in low spin, octahedral complexes where the all t2g are paired leaving all the eg unpaired; whereas nickel(II) complexes are usually formed in the high spin state1. Through these analytical methods, it was found that: hexaamminecobalt(III) chloride has three free chloride ions to form the complex [Co(NH3)6]Cl3, in the low-spin state. Pentaamminechlorocobalt(III) chloride and hexaamminenickel(II) chloride both have two free chlorine ions to form the complexes [Co(NH3)5Cl]Cl2 and [Ni(NH3)6]Cl2 respectively. As expected, pentaamminechlorocobalt(III) chloride has a low spin electron arrangement, and hexaamminenickel(II) chloride is in a high spin state. Introduction: Alfred Werner was the first to discover the structure for coordination compound in 1893, thus they were given the name "Werner Complexes". For this research he was given the Nobel Prize in 1913. Werner
Calores de neutralizacion y disolucion
CALORES DE DISOLUCIÓN Y NEUTRALIZACIÓN Piedra, A y Murillo, R Laboratorio de Fisicoquímica Experimental Escuela de Química, Universidad Nacional, Costa Rica RESUMEN: La termoquímica es la parte de la termodinámica que estudia los cambios de calor que acompañan a las reacciones químicas. El calor de disolución y neutralización se definen respectivamente como: "la variación de entalpía que se produce al disolver una determinada cantidad de soluto en cierta cantidad de disolvente", y "el calor liberado cuando se neutraliza 1 mol de base fuerte por 1 mol de acido fuerte. Durante el experimento realizado se midió inicialmente la capacidad calorífica del vaso Dewar registrando las temperaturas del sistema antes y después de adicionar agua helada, luego de lo anterior se procedió a medirá la masa necesaria de diferentes sales para preparar disoluciones a 200 y registrando las temperaturas del sistema antes y después de la adición de las sales. Para el caso del calor de neutralización también se registraron las temperaturas antes y después de la adición de los ácidos a la base. Los resultados muestran que de no tener un buen control de las condiciones experimentales, contar con el equipo adecuado y trabajar con cuidado no se obtendrán resultados satisfactorios. Palabras clave: Calor, neutralización, disolución, termoquímica. INTRODUCCIÓN La
Experiment 4 - Preparation and Reactions of Boric Acid, H3BO3
Experiment 4 Title: Preparation and Reactions of Boric Acid, H3BO3. Objectives: ) To synthesize the boric acid B(OH)3 from sodium tetraborate as starting material. 2) To use crystallization technique to obtain the final product. 3) To have a better understanding on physical properties predominantly and to study the structure of the boric acid. Instruction: Boron consist of 2 isotopes, which are 10B (19.6%) and 11B (80.4%). It is an element in p-block of the periodic table, with electron configuration of 1s22s22p1 in Group 13 (IUPAC classification). The important sources of boron are borax (sodium tetraborate) and kernite. The most common form of boron is amorphous boron, a dark brown to black amorphous powder, unreactive to oxygen, water, acids and alkalis. It reacts with metals to form borides. All boron in nature is in oxygenated form. Boron oxides and their derivatives are technologically important and are relatively inexpensive to be produced. For Boron-oxygen compounds, it contains predominantly trigonal planar BO3, and to a lesser degree of tetrahedral BO4 units, as in the borate anions. The principal oxide, B2O3 is very difficult to crystallize and normally exists in a glassy state (d=1.83 g cm-3) composed of randomly oriented B2O3 rings with bridging oxygen atoms. In the normal crystalline form, trigonal BO3 is linked through their oxygen atoms at high
Investigation of the precision and accuracy of various analytical techniques in determining the identity and quantity of barbiturates in a mixture.
Investigation of the precision and accuracy of various analytical techniques in determining the identity and quantity of barbiturates in a mixture. Aim The aim of this investigation was to identify the barbiturates given to us in a mixture (Mixture A) and to quantify the amounts present using a variety of analytical procedures for confirmation of results. Some techniques were used for preliminary investigation. Qualitative analysis Thin layer chromatography (TLC), infra red (IR) and Raman spectroscopy were used in determining which barbiturates were present in the mixture. A melting point determination was not done however because the melting point of a mixture of compounds will be less than the melting point of the individual compounds so therefore TLC analysis An analyte migrates up a layer of stationary phase under the influence of a mobile phase, which moves through the stationary phase by capillary action. The distance moved by the analyte is determined by its relative affinity for the stationary vs. the mobile phase. The sample was spotted onto a silica plate and was run alongside samples of known barbiturates in 3 different mobile phases * Dichloromethane: acetone (9:1) * Chloroform: acetone: ammonia (9:9:2) * Propan-2-ol: chloroform: ammonia (9:9:2) The plates were exposed to ammonia vapour before using fluorescence quenching as a detection method. From
Analysis and identification of two unknown polyiodide anions from two different products
Experiment S1: Analysis and identification of two unknown polyiodide anions from two different products 7 February 2022 Abstract The aim of this experiment was performed in order to analyse two solutions containing two unknown polyiodide anions. The cation used was tetramethyl ammonium iodide, forming salts with compositions and respectively. This was done by using two different mass amounts of tetramethyl ammonium iodide. The crystals formed from product A tiny splinter like and had a purple colour. The crystals from product B had a metallic green colour and were observed as long shards. The different anions, and , were determined by means of inspection of the number of moles and mass present of the anion in both products. After analysis it was concluded that product A contained the anion and product B contained the as well as and were observed to have a percentage yield of 78.6% and 76% respectively. Results The experiment was carried out as per the instructions in “Industrial Chemistry C224 Practise Manual 2022”. Product A: Table 1: Mass of solid components of product A before mixing Scale readings Mass of 0.263g Mass of 0.258g Total mass of solid components 0.521g Percentage error of scale measurements: Mass of tetramethyl ammonium iodide: Mass of iodine: Product B: Table 2: Mass of solid components of product B before mixing Scale
Experiment 3 - Stoichiometry Reaction
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
In summary, the result of the experiment shows that adding acetic acid to water will decrease the surface tension of water. As more acetic acid is added (increased concentration), surface tension will decrease even more.
MEASURING SURFACE TENSION OF AQUEOUS SOLUTIONS BY THE CAPILLARY RISE METHOD University of the Philippines, Diliman Department of Mining, Metallurgical and Materials Engineering College of Engineering ABSTRACT The capillary rise method was used to measure the surface tension of aqueous solutions of sodium chloride and acetic acid. Molar concentrations of 0.5 M and 1.0 M for each solution were tested. The results were then compared to the surface tension of pure water to observe how solute properties affect the surface tension of water. The experimental results showed that adding acetic acid solute in water lowers the surface tension of water. As the concentration of acetic acid was increased, the surface tension of water decreased even more. However, the experiment has failed to accurately show the effect of sodium chloride solutes on the surface tension of water. Nevertheless, previous studies revealed that surface tension of electrolyte solutions, such as NaCl solution, increase with increasing concentration. The experiment revealed several disadvantages of the capillary rise method, such as difficulties in firmly holding the equipment, in reading the liquid level inside the capillary, in keeping the temperature constant, and in accurately marking the liquid level with a pen. Nevertheless, the capillary rise method proved to be comparatively reliable, provided that
Dumas Method
Introduction In order to identify new materials, scientists use a variety of chemical and physical methods to determine molecular masses. One of these methods includes the Dumas method for determining the molecular weight of a volatile liquid. This method, which was proposed by John Dumas in 1826, makes use of a volatile liquid (vaporizes at a relatively low temperature) and allows this liquid to be heated in a water bath to a known temperature and escape from a flask through a tiny opening (Giunta, 2003). In this situation, vapours are assumed to be obeying the Ideal Gas Law, which is PV = nRT. P is the current atmospheric temperature, measured in atmospheres, V is the volume of the flask, n is the moles of the gas and T is the temperature of the water bath, measured in degrees Kelvin (Weisstein, 2007). R remains a constant, which is 0.08206 L atm/K mol (Weisstein, 2007). The equation used to solve for n (mass/molecular weight) is substituted into the Ideal Gas Law and then rearranged in order to solve for molecular weight (MW). As a result, the equation used in the Dumas Method is as follows: MW = mRT/PV (Giunta, 2003). The Dumas method depends on a lot of things to go right. For example, the liquid used in this experiment must be volatile enough to vaporize at high temperatures (Giunta, 2003) On the other hand, the liquid must not be too volatile to ensure that a
To study the enthalpy changes (H) of various acid-base neutralization.
Experiment 1- Heat of Neutralization Title: Heat of Neutralization Objective: To study the enthalpy changes (?H) of various acid-base neutralization. Introduction: Neutralization is the reaction between an acid and a base, and is an exothermic reaction. The enthalpy of neutralization is the heat produced when an acid and a base react together in dilute aqueous solution to produce one mole of water. Strong acids and strong alkalis are completely dissociated in dilute solution, so the reaction between any strong acid and strong alkali may be represented as following: H+(aq) + OH-(aq)--> H2O(l) ?HO = -57.3 kJ mol-1 If a weak acid or alkali is used, or if both are weak, then the enthalpy of neutralization is usually lower than -57.3 kJ mol-1 This is because weak acids and weak alkalis are only slightly ionized in aqueous solution, and energy is absorbed in ionizing the un-ionized molecules. CH3COOH(aq) + NH3(aq)-->CH3COONH4(aq) ?HO = -32.0 kJ mol- The temperature rise due to the heat given out can be used to find the end-point of titration. In this experiment, TWO methods are used to find the end-point of titration, which is then used to : (i) find the molarity of a ammonia, and (ii) the enthalpy change of neutralization. Different combinations of acid and alkali are used and compared. Procedures: Neutralization between aqueous base and
Using Volatile Liquids with Set Conditions to Find Molar Mass of an Unknown
Using Volatile Liquids with Set Conditions to Find Molar Mass of an Unknown Erin Lab Performed: October 14th, 2008 Section 006 T.A: Teresa Introduction The purpose of this experiment was to find the molar mass of the unknown substance and compare it to the universal molar masses of different alcohols. This process can be done using the ideal gas law which is pressure and volume is proportionate to number of moles, the universal gas constant and temperature (Department of Chemistry, 2008). Jean Baptiste Dumas, a French chemist whom began his career as a pharmacist and later greatly contributed to modern science. His most well known and accredited work is studying vapour densities of elements which in turn is used to discover their molar masses. However, the scientist did not directly develop the Dumas method because of the nonexistence of the mole at that time. The Dumas method uses the formula M=mRT/PV,M for molar mass, m for mass, R for the universal gas constant, T for temperature, P for atmospheric pressure and V for volume (Sloane, Thomas O'Conor, 1909). Molar mass is the mass of one mole of a substance. The number of moles of a substance is the number of atoms in that element compared to the number of atoms of a carbon-12 molecule. For this experiment we used the ideal gas law. The ideal gas law is all collisions between molecules are free of intermolecular
