The Development of the Periodic Table of the Elements
The Development of the Periodic Table of the Elements The periodic table is defined as the most common arrangement of the periodic system. This is the classification of chemical elements into periods (corresponding to the filling of successive electron shells) and groups (corresponding to the number of valence electrons) and describes the modern version that is used today. However, this was not always how it was structured and described - like the atom, the Periodic Table has been developed over time due to the contributions of a number of scientists (and is still developing even today). Long before the development of the modern Periodic Table, ancient philosophers such as Aristotle believed the world to be made up of four distinct elements: earth, water, air and fire. Although this is not true, they were thinking along the right lines as these are examples of the states of matter solids, liquids, gases and plasma. The first significant contribution towards the modern Periodic Table was made by the French chemist Lavoisier in 1789, who with his wife compiled the first modern chemical textbook named Traite Elementaire de Chimie (Elementary Treatise of Chemistry), which included a list of the known elements at the time. An advantage of Lavoisier's work is that he distinguished between metals and non-metals but a disadvantage was that he included some compounds and mixtures
Write an essay on electrode potentials.
F7 Essay Writing (Electrode Potentials) Q. Write an essay on electrode potentials. Outlines: (I) What are electrode potentials? (a) associated with equilibria of redox systems (half cells): e.g. metal / metal ion system ; non-metal / ion system ; ion / ion system; (b) reactivity, tendency for reduction to occur (losing electrons) and potential difference; (c) the potential difference of a half cell cannot be measured alone, but a relative value could be measured with another reference half cell / reference electrode; (d) a standard hydrogen electrode [SHE] (in which the emf is defined as zero) is used as the reference electrode; (II) How are electrode potentials measured? (a) concentration, temperature and pressure affect the emf of SHE, and the standard electrode potentials are obtained under conditions of 298K, 1 atm and conc. of 1M. (b) set up a cell with SHE and a salt bridge of electrolyte (e.g. KNO3); (c) a potentiometer is used to measure the cell emf (maximum potential difference), and the sign of cell emf = polarity of the right hand electrode. (III) How are electrode potentials used? / Application of electrode potentials? (a) calculation of cell emf ; (b) prediction of reaction feasibility and limitations. ~ Sample Essay ~ An electrode potential is the difference in an potential between an electrode and its surrounding electrolyte. It is
Science at Work Research . Dulux Paints, a Hospital, a leisure centre and a GPs surgery.
For this project I have sent a letter to each company, I have emailed 1 of the companies and visited 2 of the companies in order to help me with my research. Although not all companies gave me the relevant information, I also used the internet to help me fill in the missing gaps. Production Organisations The only product organisation I have chosen to do is Dulux. Dulux is a paint company. Dulux Customer Care Centre ICI Paints Wexham Road Slough SL2 5DS Tel: 08444 817 817 Dulux produce a wide range of different paints and products both interior and exterior to help you paint. Here are a few examples of what products they make. Paint Paint is any liquid liquefiable or mastic composition which after application to a substrate in a thin layer is converted to a solid film. Products made for interior: Paint pod: Paintpod roller system, Paintpod matt emulsion, Paintpod silk emulsion, Paintpod 2m extension tube, Paintpod extra reach handle, Paintpod roller sleeve, Paintpod dip tube, Paintpod edging brush, Paintpod spare parts Main Range: Matt, Natural hints matt, Feature wall matt, Soft sheen, Solid emulsions matt, Solid emulsions silk, Non-drip gloss, Satin wood, Professional liquid gloss, Pure brilliant white eggshell, Quick dry gloss, Quick dry satin wood, Tile paint, Cupboard paint. Exterior products: Products made for exterior: Main range: non-drip gloss,
Investigate the Properties of Ionic and Covalent substances
Title: To Investigate the Properties of Ionic and Covalent substances Introduction: Certain properties of compounds, such as polar and non- polar solvents, melting point and conductivity of electricity, can be used to distinguish between Ionic and Covalent substances. Aim: To determine whether common laboratory substances are ionic or covalent in nature. Apparatus/Materials: Sodium Chloride Test Tubes Sucrose Glass Rods Naphthalene Beaker (2- 100cm3) Copper (II) Sulfate Battery Calcium Carbonate Connecting wires Calcium Oxide Electrodes Spatulas Bunsen burner Tongs Method(1): Heating Substances Approximately two spatulas of sodium chloride was placed into a test tube and its contents were gently heated at first then heated strongly until no further change occurred. This was repeated with the other salts. Method(2): Solubility of Substances Two spatulas fall of sodium chloride was poured into breakers 1 with water and oe with ethanol. Solution was mixed and was held for conductivity test same was done for other salts. Method(3): Conductivity Electrodes were connected to connecting wires and
Analysis of Oxygen Absorber. How can the oxygen absorber absorb oxygen in the food package? What is the composition of the oxygen absorber? In this activity, we will plan and carry out an investigation to find out the chemical nature of the oxygen absorb
Date of experiment: 06/10/2010 Name: Cheung Lap Kwan (6) Group mates: Chan Wing Ho (5) Ho Chun Yung (11) Ho Grace Yan Yu (12) Po Leung Kuk Ngan Po Ling College 2010-2011 Form 6 Chemistry Laboratory Report Title: Chemistry Project: Analysis of an Oxygen Absorber Introduction: In a moon cake package, there is often a packet of oxygen absorber provided with each moon cake. The oxygen absorber is usually used for food storage, because oxygen is the main substance which causes the degeneration of food. Some food contains fat or oil. When the food is exposed in air, the fat and oil may be oxidized by oxygen. This process is called "rancidity" (The main theory of rancidity is not discussed in this report). After the rancidity, the product may be harmful to human. So oxygen absorber is needed to reduce the amount of oxygen in package. Oxygen in air also can facilitate the growth of mold. As we all know, the mold on the food release toxic substances. It is dangerous for us to take in the food contains these toxic substance. When we use oxygen absorber, the concentration of oxygen is decreased. Low oxygen concentration can inhibit the growth of mold. Besides, oxidation of food can cause the colour change of food. If the colour of foods changes, people will have a lower longing to have these food. Using oxygen absorber can prevent the change of colour.
Revision Notes. Substances Manufactured for use in Industries. Chemicals, alloys and polymers.
.1 Manufacture of Sulphuric Acid Uses of Sulphuric Acid Sulphuric Acid, H2SO4, has many uses in our daily life. A few examples are: (a) Manufacture of fertilisers such as ammonium sulphate, (NH4) 2SO4 (b) Manufacture of electrolyte in lead-acid accumulators (c) Manufacture of soaps and detergents (d) Manufacture of pesticides (insecticide) (e) Manufacture of plastic items such as rayon and nylon (f) Manufacture of paints Manufacture of Sulphuric Acid in industry . Sulphuric acid, H2SO4, is manufactured in industry through the Contact Process. 2. The manufacturing of sulphuric acid, H2SO4, in industry involves three stages. Stage Aim Stage 1 Sulphur dioxide, SO2, gas can be produced by burning sulphur in air. S + O2 SO2 To produce sulphur dioxide, SO2, gas Stage 2 The gas mixture of sulphur dioxide and oxygen is passed over vanadium(V) oxide, V2O5 (catalyst) at a temperature of 450-500 ºC and under pressure of 1 atmosphere. 2SO2 + O2 2SO3 To produce sulphur trioxide, SO3 gas Stage 3 Sulphur trioxide, SO3, gas is dissolved in concentrated sulphuric acid, H2SO4 to form oleum, H2S2O7. SO3 + H2SO4 H2S2O7 Water is then added to the oleum, H2S2O7 to dilute it to produce sulphuric acid, H2SO4. H2S2O7 + H2O 2H2SO4 To produce sulphuric acid, H2SO4 The three stages involved in the Contact process Environmental
In this experiment, the rate of decomposition is calculated by measuring the volume of the product gas using water displacement.
Decomposition of Bleach Introduction In this experiment, the rate of decomposition is calculated by measuring the volume of the product gas using water displacement. The reactant used is household bleach, which contains 5 to 6% of NaClO. The decomposition can be stated in this following equation: 2 ClO- (aq) --> 2 Cl- (aq) + O2 (g) To measure the rate of decomposition, a catalyst is needed to fasten the reaction. A suitable catalyst is Co2O3, which is produced from mixing Co(NO3)2 and bleach. The reaction can be described as follows: 2 Co2+ (aq) + ClO- (aq) + 2H2O (l) --> Co2O3 (s) + 4 H+(aq) + Cl-(aq) Purpose The objective of this experiment is to determine the rate of decomposition of bleach by measurement of gas production at several different temperatures. Hypothesis The decomposition rate will increase if the surrounding temperature increases. If the surrounding temperature increases by 10°C, the reaction rate will double. If the temperature decreases by 10°C, then the reaction rate will decrease by half. Materials * Household Bleach * Co(NO3)2 solution * Erlenmeyer flask * Stopper and tube * Ring stand * Burette * Graduated cylinder * Thermometer * Burette clamp Procedure Refer to lab instruction sheet - "Decomposition of Bleach" Data Table 1 - Accumulation of Oxygen at Room Temperature (24°C) Time Interval (s) Volume of Gas
Aim: To determine the relative composition of a mixture solution containing sodium ethane-1, 2-dioate and ethane-1, 2-dioic acid.
DETERMINATION OF THE RELATIVE COMPOSITION OF A MIXTURE SOLUTION AIM To determine the relative composition of a mixture solution containing sodium ethane-1, 2-dioate and ethane-1, 2-dioic acid. INTRODUCTION Potassium permanganate KMn is a strong oxidizing agent which reacts with reducing agent ethanedioate ion to give and C + 2 Mn+ 16 2+8+10 Sodium hydroxide (NaOH) reacts with acid to give water . the reaction is shown with the following equation + To investigate the relative composition of the mixture solution, it has to be titrated with NaOH first with phenolphthalein as indicator and then with acidify KMn as Mn react with both compound. KMnhas to be acidified first, otherwise brown ppt of Mn is formed instead of 2 H2O + MnO4- + 3 e- › Mn+ 4 In addition to that, the reaction solution has to be warmed to about 70 as the reaction rate is very slow. MATERIALS AND APPARATUS beaker measuring cylinder. Safety spectacles beaker conical flask pipette ,25 burette ,50, and stand wash bottle white file electrical heater sulphuric acid Potassium permanganate KMn solution Mixture solution PROCEDURE . 25.00of the mixture solution was transferred into a 250conical flask using a pipette rinsed by distilled water and the mixture solution 2. The burette rinsed by distilled water and NaOH is filled with NaOH 3. Titrate the mixture
Determination of the equilibrium constant for the reaction
Chemistry TAS Report . Experiment Number : 10 2. Date : 18/01/2008 3. Title : Determination of the equilibrium constant for the reaction : Fe3+(aq) + SCN-(aq) <=> FeSCN2+(aq) 4. Aims/Objective : To determine the equilibrium constant for the reaction : Fe3+(aq) + SCN-(aq) <=> FeSCN2+(aq) 5. Introduction / Theory: In this experiment, the equilibrium constant for the formation of a complex ion, FeSCN2+(aq), is determined. Complex ions, thiocyanatoiron(III) ions, are formed from iron(III) ions and thiocyanate ions in aqueous solution : Fe3+(aq) + SCN-(aq) <=> FeSCN2+(aq) (1) The equilibrium constant for this reaction is: Kc = [FeSCN2+(aq)] (2) [Fe3+(aq)][SCN-(aq)] The product complex ion is the only one of the three species which has an appreciable color (blood-red). 6. Relevant Equations/Chemical Reactions Involved : Fe3+(aq) + SCN-(aq) <=> FeSCN2+(aq) 7. Chemicals : 0.002 M KSCN(aq) 50 cm3 0.2 M Fe(NO3)3(aq) 20 cm3 8. Apparatus and equipment : Boiling tube 5 Dropper 2 0 cm3 measuring cylinder Lamp 25 cm3 measuring cylinder Wash bottle Safety spectacle 250 cm3 beaker 9. Procedure : . 0.2 M Fe(NO3)3(aq) was used and 10 cm3 of 0.08 M, 0.032 M, 0.0128 M, 0.00512 M Fe(NO3)3(aq) were prepared respectively. 2. The solutions were added by using 10 cm3 measuring cylinder to
Indigestion Tablet
Chemistry Lab Report The Best Indigestion Tablet To: Miss Lina Subeh By: Dara Masri Abstract: In this experiment, we are to find which antacid (indigestion tablet), Rennie or Novagel, is the most effective. This is done using titration method using a burette filled with Sodium Hydroxide, in order to measure the amount used to neutralize or lower the pH of the tablet powder mixed with Hydrochloric Acid. This will be indicated by a change in color using Methyl Orange Indicator after adding Sodium Hydroxide. The more the amount of Sodium Hydroxide used, the more it will show that the type of that indigestion tablet is not effective, because we will conclude that the Hydrochloric Acid was not neutralized or the pH of it was lowered, so more Sodium Hydroxide was needed to do that. After doing this experiment, we found out that Rennie needed less Sodium Hydroxide to neutralize its acidity than Novagel, and that meant that Rennie is more effective than Novagel. Key Words: Indigestion Rennie Novagel Sodium Hydroxide Methyl Orange Indicator Titration Experiment Table of Contents: Abstract ............................................................................... 2 Aim ...................................................................................... 4 Hypothesis ............................................................................ 4 Literature
