Titration Lab Report
CHEMISTRY LAB Titration Curves of Strong and Weak Acids and Bases Processing the Data: Questions: . Examine the time data for each of the Trials 1-4. In which trial(s) did the indicator change color at about the same time as the large increase in pH occurred at the equivalence point? In which trial(s) was there a significant difference in these two times? In all the 4 trials, the time taken for color change and the time taken for a large increase in pH was the same, leaving no significant difference between the two values. 2. Phenolphthalein changes from clear to red at a pH value of about 9. According to your results, with which combination(s) of strong or weak acids and bases can phenolphthalein be used to determine the equivalence point? The combination of a Strong Acid and Base will give us the equivalence point: there will be a color change of phenolphthalein at pH 9. It is also observed that the reaction between a Weak Acid and Strong Base can be used to obtain a pH of 9. 3. On each of the four printed graphs, draw a horizontal line from a pH value of 9 on the vertical axis to its intersection with the titration curve. In which trial(s) does this line intersect the nearly vertical region of the curve? In which trial(s) does this line miss the nearly vertical region of the curve? For Trials 1 and 3, the horizontal line from pH 9 intersects the S curve. For
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
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
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
Experiment investigating hydrogen bonding in different chemicals.
Tsuen Wan Public Ho Chuen Yiu Memorial College Form 6 Chemistry Practical Experiment 8: Hydrogen Bonding Date of experiment: 27-1-2011 Objective: A. To discover the existence of hydrogen bonds between ethanol molecules B. To measure the strength of hydrogen bond formed between ethanol molecules C. To investigate the formation of hydrogen bonds between molecules of ethyl ethanoate and trichloromethane D. To measure the strength of hydrogen bonds formed between molecules of ethyl ethanoate and trichloromethane Introduction: A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond. These bonds can occur between molecules, or within different parts of a single molecule. The hydrogen bond (5 to 30 kJ/mol) is stronger than a van der Waals interaction, but weaker than covalent or ionic bonds. This type of bond occurs in both inorganic molecules such as water and organic molecules such as DNA. Intermolecular hydrogen bonding is responsible for the high boiling point of water (100 °C) compared to the other group 16 hydrides that have no hydrogen bonds. Intramolecular hydrogen bonding is partly responsible for the secondary, tertiary, and quaternary structures
Acid-Base titration by double indicator method
Date: 01/12/2010 Objective To determine the proportions of sodium carbonate and sodium hydroxide in a mixture solution using double indicator method. Procedures . 25 cm3 of the mixture solution was pipetted into a conical flask. 2. Two drops of phenolphthalein indicator were added into the conical flask. 3. The mixture solution was titrated with the given standard hydrochloric acid(0.098M). 4. The mixture was titrated to the end-point. 5. At the end point, the pink colour of phenolphthalein indicator was just discharged. 6. The burette reading (x) was recorded. 7. Two drops of methyl orange and a further quantity of acid were added 8. The mixture was titrated to the end-point. 9. At the end point ,the yellow colour of the methyl orange changed to orange. 0. The reading of that further quantity of acid (y) was recorded. 1. The steps above were repeated 3 times. Results: Volume of piptte used: 25 cm3 The concentration of the hydrochloric acid used: 0.098M x Trial 2 3 Final burette reading / cm3 2.40 31.80 29.40 2.70 Initial burette reading / cm3 0.10 9.50 7.20 0.30 Volume of acid used(x) / cm3 2.30 2.30 2.20 2.40 Mean value of x= (12.30+12.20+12.40)/3 =12.30 cm3 y Trial 2 3 Final burette reading / cm3 9.50 38.80 36.60 9.80 Initial burette reading / cm3 2.40 31.80 29.40 2.70 Volume of acid used(x) / cm3 7.10 7.00
ACID RAIN The majority of people consider rain to be an undamaging weather occurrence. However the increase in acidity of rain is both unsafe and damaging. In order to fully understand the term acidity,
ACID RAIN The majority of people consider rain to be an undamaging weather occurrence. However the increase in acidity of rain is both unsafe and damaging. In order to fully understand the term acidity, it is essential to know something about the pH scale. This scale has a range of 0 to 14, with 7 being neutral. Anything below 7 (0-6) is known to be acidic and anything above 7 (8-14) is alkaline. A change in only one unit is equal to a tenfold increase in the strength of the acid or base. Therefore a unit change from pH 6 to pH4 is equal to a 10 x 10 increase in it acidity. Taking the above into consideration, it is easy to see how the normal phenomenon "rain" is becoming more and more acidic as its pH has dropped from around 6and 7 to about 4.3and 5.3.This occurrence is known as Acid Rain and was first noted in1852 by the English chemist called Robert Angus Smith. Acid rain in other words is the term used to describe rainfall that has a pH level below5.6. It is a form of air pollution that is currently a theme of huge debate due to its wide spread damages. It is responsible for the destruction of thousands of lakes and streams in the United States, Canada and parts of Europe. Acid Rain formation The two most important primary sources of acid rain are sulphur dioxide (SO2) and oxides of nitrogen (NOx). Sulphur is a colourless, pungent gas produce during the
Nuclear Fusion as energy provider
For ?-decay, unstable atom emits an ?-particle, this can also apply to ?-decay. To distinguish ?-decay and ?-decay, here is a number of characteristic of each of the decay: relative charge, relative mass, nature, range, material to stop, deflection in electric field and magnetic field. ?-emission ?-emission Relative charge +2 -1 Relative mass 4 0.00055 Nature 2 protons + 2 neutrons (Helium nucleus) Electron Range 5cm 6m Material to stop Paper Aluminium(5mm thick)[] Deflection in electric field [2] Slightly towards negative terminal Greatly towards positive terminal Deflection in magnetic field[2] Slightly upwards Greatly downwards As an example, Bismuth can decay into Thallium and Polonium by emitting ?- and ?-particle respectively. For ?-decay of Bismuth: For ?-decay of Bismuth: The example above can show ?-particle is Helium particle while ?-particle is electron. Radioactive decay is different from fission reaction. Radioactive decay Fission . unstable . absorb 1 neutron 2. emit ?/?/?- particle 2. oscillate 3. become other elements 3. unstable 4.Fission (split) 5. give out 3 neutrons Fission reactions differ from radioactive decay both in the way that the reaction must be started and in the type of products that are formed [1]. Radioactive decay is a passive action, while fission is active. For radioactive decay, the atom is unstable;
risks of electricity
WHAT ARE THE RISKS FROM ELECTRICITY? Harm can be caused to any person when they are exposed to 'live parts' that are either touched directly or indirectly by means of some conducting object or material. Voltages over 50 volts AC or 120 volts DC are considered hazardous. Electricity can kill. Each year about 1000 accidents at work involving electric shocks or burns are reported to the Health and Safety Executive (HSE). Around 30 of these are fatal, most of them arising from contact with overhead or underground power cables. WHO IS MOST AT RISK FROM ELECTRICITY? Anyone can be exposed to the dangers of electricity while at work and everyone should be made aware of the dangers. Most electrical accidents occur because individuals: * are working on or near equipment which is thought to be dead but which is, in fact, live * misuse equipment or use electrical equipment which they know to be faulty. LEGAL DUTIES AND OBLIGATIONS AROUND ELECTRICITY As well as a moral duty on employers to protect employees and members of the public, General Health and Safety Legislation covers all employers and workplaces. In addition, specific duties and obligations are laid out in the following regulations: These regulations apply to all aspects of the use of electricity within the workplace from electrical supplies to the use of electrical equipment. They place a duty on employers,
