Solid / Liquid Separation
Solid/Liquid Separation (under gravity) Thickeners Why? For the purposes of separating solids from liquids en masse rather than of solids classification, particularly in the colloidal region (<2µm), thickeners have several advantages over centrifuges. What? A thickener consists of a large (cylindrical) tank (often) with a broad conical section at the base, at the centre of which is an outlet pipe/valve assembly. The stream from this outlet is termed the underflow. Around the rim of the tank is a tray, rather like a gutter, into which clarified liquor (the overflow) flows (as a result of overspill from the rim). A set of slowly rotating mechanical rakes gently scour sediment and direct it to the underflow. Feed is introduced at the centre of the tank (and distributed across it) at some distance below the surface. How? Overview Cursory consideration of the mass balance for such a device indicates that all solids must leave via the underflow and must not therefore be presented with any opportunity to reach the (overflow at the) rim of the tank. The design must ensure this. At a given feed rate, the vertical flow velocity of liquid (both up and down) in the device will decrease as the area is increased and vice versa. In the upper part of the tank net downward motion of solids is reduced, but in the lower section it is increased - relative to a freely settling
Comparing the Energy Outputs of Different Fuels.
Comparing the Energy Outputs of Different Fuels. Aim To investigate the amount of energy released from different fuel sources and to compare respective costs of the fuels per kilo joule of energy transferred. Hypothesis I suggest the longer the hydro-carbon chain of the fuel being burnt the greater the energy released per gram of fuel burnt. However given the price of fuel per gram, typically, does not increase proportionately to the chain length, the fuel releasing the most energy may not necessarily be the most cost effective. Method Apparatus: * Copper beaker/can * Ceramic crucible (with lid) * Frame and clamp * Heat Proof Mats * Thermometer * Balance * Tin foil * Small lengths of string (to act as wicks) * Measuring cylinder * Distilled water * Selection of Fuels* *For this comparison -Methanol C H3 OH -Ethanol C2 H5 OH -Propanol C3 H7 OH -Butanol C4 H9 OH and -Candle Wax Procedure: .Start by setting measuring out 200ml of water, transfer to the copper beaker and take the water temperature. 2.Now clamp the beaker to the frame and adjust so that the bottom of the beaker is at a height exactly 4cm from the top of the crucible (when the crucible is directly under it). 3.Remove the crucible from its position, carefully pipette approximately 1g of methanol into it and replace the lid (this is to reduce any loss through evaporation).
Using a Ballistic Pendulum To Demonstrate the Law Of Conservation of Momentum.
November 3, 2003 Using a Ballistic Pendulum To Demonstrate the Law Of Conservation of Momentum Abstract The concepts of conservation of momentum and conservation of mechanical energy were investigated and used to demonstrate that the law of conservation of momentum is valid. A ballistic pendulum was used to show that the initial velocity of a projectile could be determined using these concepts. To verify the results of the ballistic pendulum experiment, the initial velocity was also calculated by firing it horizontally and calculating the time and distance traveled. The percent difference between the two values for initial velocity was 13.0%. Introduction One of the most useful laws of physics is the law of conservation of momentum. For instance, in an inelastic collision, the change in momentum of the combined objects can be used to figure the momentum of the objects before the collision. In this experiment, a ballistic pendulum was used to demonstrate that the law of conservation of momentum is valid. A ballistic pendulum is a pendulum that begins in a vertical resting position, while a projectile is fire at the end of the pendulum. The pendulum must be capable of incorporating the projectile so that the collision is inelastic and the projectile and pendulum move as a single unit. Examples would be a bullet into a block of wood, or a ball into a trapping basket,
Double Slit Interference
RYERSON UNIVERSITY DEPARTMENT OF PHYSICS TITLE OF EXPERIMENT: Double Slit Interference Objective and Background: The objective of the experiment was to observe the patterns of interference and diffraction produced by monochromatic light, in this case laser light, passing through double-slit apertures, and confirm that the bright fringes on the pattern have the same positions computed by theory. In 1801, an English physicist named Thomas Young performed an experiment that strongly inferred the wave-like nature of light. Because he believed that light was composed of waves, Young reasoned that some type of interaction would occur when two light waves met. Laser light produces an intense beam of monochromatic (single frequency) light. All the waves across the beam are in phase. The beam illuminates the slits, which are narrow to ensure adequate diffraction. The diffracted beams from the two slits overlap causing the waves in the beam to superimpose. The interference pattern due to the superposition of the waves appears on the screen as alternate dark and bright bands, called fringes. The bright fringes are caused by constructive interference and the dark fringes by destructive interference. The angle between the central fringe and bright fringes obeys the following formula: (m = 0, 1, 2, 3 ...) where d is the distance between two slits, is the angle that the mth maximum
Compare wave and particle theory. In which circumstances is each one used.
Compare wave and particle theory. In which circumstances is each one used. The understanding of light has developed mainly since the 1600's. In 1666, Isaac Newton discovered that white light is made up of all colours. Using a prism, he found that each colour in a beam of white light could be separated. Newton proposed the theory that light consists of tiny particles that travel in straight lines through space. He called these particles corpuscles, and his theory became known as the corpuscular theory. About the same time that Newton proposed his theory of light, the Dutch physicist and astronomer Christiaan Huygens suggested that light consists of waves. He proposed the wave theory to explain the behaviour of light. The corpuscular and wave theories appear to be completely opposite, and scientists argued about them for about 100 years. Then, in the early 1800's, the English physicist Thomas Young demonstrated the interference of light. He showed that two light beams cancel each other under certain conditions. As it is hard to understand how interference could occur with particles, most scientists accepted Young's experiment as proof of the wave theory of light. In 1901 Max Planck found a formula, which was correct for all wavelengths. Planck's formulation fitted the precisely determined spectrographic data then with great accuracy. E = h f where h is the
An Introduction to Solids and their Properties
An Introduction to Solids and their Properties In this piece of work I will learn how particle models can show the difference between solids, liquids and gases and look at the properties and theories about the models. Then I will investigate further into what a physical change is and also what a geological change is. The States of Matter There are 4 states of matter. Matter is basically stuff that takes up space, without it the universe would be nothing, and wouldn't exist. Matter is made up of many particles and can be found in many different states. These states or 'phases' can very depending on the temperature or pressure acting on the particles, and often change state. Many people believe there are 3, but scientifically speaking there are 4 different states of matter. The main 3 are solids, liquid and gases, and the 4th one- which is a rare state of matter- is plasma. We don't get plasma that much in everyday life so that's why its often neglected and its taught that there are 3 states of matter. Here are more detailed definitions of solids, liquids, and gases and about their particles: * Solids- Solids are basically solid substances. The particles in a solid are packed very tightly together, and are touching each other. The particles are vibrating slightly, even though it is a completely solid substance, as the solid is so tightly packed together the particles cannot
X-ray Photoelectron Spectroscopy.
X-ray Photoelectron Spectroscopy Basic Principles XPS uses soft X rays (200-2000eV) radiation to examine core levels. It is based on a single photon in/electron out process. "Photoelectron spectroscopy involves the ejection of electrons from atoms or molecules following bombardment by monochromatic photons", (Hollas, J. M., 1998, p426). X rays are used to remove the core electrons. The photon is absorbed by an atom in a molecule or solid, leading to ionization and the emission of a core (inner shell) electron. This can be represented by the equation below - A + h? A+ + e- The energy of the photons is high enough to ionise core level electrons. The core ionisation energies are characteristic of the individual atom. As electron only in the first few nanometres of the surface are emitted and contribute to XP spectra peaks, this gives rise to surface selectivity. Even though the x-rays may penetrate deeply to produce photoelectrons, most of these electrons lose energy in numerous inelastic collisions. This causes only a few monolayers to give undistorted photoelectron spectra, (www.geocities.com/capecanaveral/6367/esca1.htm, 3/10/03). Surface sensitivity ranges from 10-1 to 100 monolayer for XPS. XPS is more sensitive to core levels than to valence-band electrons, (Ibach, H. & Roy, D., 1977, p10). Binding energies The core electron of an element has a
Radicals In Organic Synthesis.
Radicals In Organic Synthesis. Gomberg reported the 1st free radical in 1900; a century has passed since he first discovered the triphenylmethyl radical. For many years the chemistry of free radicals was very much the province of mechanistic and physical organic chemists with their application to synthesis not extending much past the occasional use of Kolbe electrolysis or oxidative coupling of phenols. However with time these recent situations have changed. The realisation that radical methods are often very compatible with a range of functional groups, without further protection, has led to an increased interest in the use of radicals in synthesis. Radicals or Free Radicals can be defined as a species that contains at least one unpaired electron. Radicals in general are extremely a reactive species; reacting rapidly with the majority of organic molecules. These include molecules such as alkanes, which are impervious from attack via ions. The large proportion of radicals only exist as a transient intermediate, never abundant in large concentrations. The occurrence of radical intermediates can often be inferred from the nature of the reaction products or from a study of kinetics. The Formation of Radicals: Most of the important radical reactions proceed by a chain mechanism, the crucial step requires the generation of a radical from an appropriate pre - cursor. The
Practical 1: Granule Manufacture Introduction: Tablets are the single most common formulation used today. They account for 50% of total market share. The main reasons for this are the many advantages that come with formulating a drug as a tablet, such as: * Relative ease of manufacture compared to a cream for example * Uniformity of dose, compared to a suspension * Stability of dosage form, tablets can have a shelf life of over a year * Controllability of drug release. This does not occur in formulations such as creams. The ingredients of a tablet differ from one drug to another, and the different compositions will be reflected in the tablets therapeutic effectiveness. Variations in particle size will be reflected in a tablets physiochemical properties. A tablet will contain, primarily, the active ingredient, i.e. the drug that is being delivered. The tablet will also contain other ingredients that are necessary to formulate a satisfactory tablet, these ingredients are called excipients, and common excipients include: Binders: such as polyvinylpyrrolidin (PVP). These exert an effect by holding particles together; they induce the formation of granules. Diluents: such as lactose and microcrystalline cellulose. Diluents are used to increase the mass of the powder, for example if the over all mass of a tablet needed to be increased to 50mg, a diluent would be
Cis / Trans Isomerism in Capsaicin Stereoisomers are "compounds that have the same atomic connectivity but differ in the spatial arrangement of constituent atoms"
Cis/Trans Isomerism in Capsaicin Stereoisomers are "compounds that have the same atomic connectivity but differ in the spatial arrangement of constituent atoms" (Ref 10, p. 93). In other words, stereoisomers are molecules that 1. are composed of the exact same atoms, and where 2. each atom in one molecule is connected to the same neighbors as its twin in the other molecule, but 3. the three-dimensional orientation of the molecules is different. Sounds impossible, right? Well, consider a pair of leather gloves. Each is composed of identical components- four fingers, a thumb, and a palm section. In each case, the components are connected the same relative to each other- the thumb is connected to the palm on the outside, the index finger is connected to the palm between the thumb and the middle finger, etc. Yet, the 3-D orientation of the two gloves is different. You can prove this to yourself by trying to put a glove on your right hand. The right glove will fit, but the left glove won't. The connectivity of the parts is the same, but their 3-D orientation is different. One type of stereoisomerism common to compounds with C=C bonds is called cis/trans isomerism. Cis/trans isomerism occurs because a double bond prevents the internal rotation that would ordinarily occur if the double bond was a single bond. The atoms in a molecule are not static objects