Lab report Determination of Enthalpy Change of Neutralization
Experiment 7 Determination of Enthalpy Change of Neutralization Aim, introduction, apparatus and procedures refer to the instruction sheet. Risk Assessments The thermometer used in the experiment is neither made up of alcohol or mercury. Both substances are harmful to our human body. Alcohol will catch fire quickly when it is in contact with fire or any flammable substance. Mercury is a poisonous and extremely toxic chemical. It can cause both chronic and acute poisoning. As a result, we must handle or use the thermometer carefully. Don't use the thermometer as the gas rod to stir the solution. If the mercury or alcohol is spilt out from the thermometer, we must leave the area of alcohol or mercury and then call the teacher immediately as we don't know how to clean the mercury or alcohol at our level. Secondly, hydrochloric acid used in the experiment is corrosive although it is diluted. It can hurt our skin and irritate our eyes. Therefore, we should handle it very carefully. If the acid is spiller out and fell on our skin or eyes, we have to wash the infected area with plenty of running water or eye wash bottle. Moreover, the hydrogen gas produced from the reaction between calcium and hydrochloric acid is flammable. Explosion will occur if there is fire. As a result, we should keep the experiment away from the fire and conduct the experiment under the good ventilation
To Determine the Concenteration of a Limewater Solution
To Determine the Concentration of a Limewater Solution The aim of this investigation is to determine the concentration of a limewater solution using hydrochloric acid with a known concentration of 2.00mol dm-3. In this investigation, I will be using titration to determine the concentration of the limewater solution. "Titration is a way of measuring quantities of reactants, and can be very useful in determining an unknown concentration."i But before I can undergo the titration, I will need to dilute the hydrochloric acid. This is because the limewater has an approximate concentration of 1g dm-3, whereas the hydrochloric acid has a concentration of 2.00mol dm-3. This is important because if the hydrochloric acid has a higher concentration than the limewater, then not all of the solution will neutralise fully, which will not give us accurate or reliable results. Before the titration, I will also have to work out which indicator should be used in this experiment. The indicator is essential as it shows the end-point where the entire base has reacted to give a neutral solution. As both hydrochloric acid and calcium hydroxide are strong basesii iii, I have a choice of using either methyl orange or phenolphthalein as my indicators. I would be using phenolphthalein as my indicator, because the phenolphthalein will change colour just before the equivalence point and
Dipoles and their importance
Dipoles A dipole is simply a molecule with a positive end and a negative end. When a molecule has a dipole, it is described as polarised. There are three main ways in which molecules can become polarised, possessing permanent dipoles; instantaneous dipoles and induced dipoles. Molecules can also obtain polar-covalent bonds, which are also a type of dipole. Permanent Dipoles Certain molecules possess a constant dipole due to atoms being bonded together with substantially different electronegativities, so that one atom attracts the shared electron cloud much more than the other(s) - causing that atom to have an increased negative charge and leaving the other atom(s) with an increased positive charge. Molecules with a permanent dipole are said to be polar molecules, an example being hydrogen chloride - the chlorine atom being more electronegative and so acquiring a slight negative charge as the shared electron cloud is pulled more strongly towards the chlorine atom. The hydrogen atom is left with a slight positive charge as electrons exist further away from it due to the presence of chlorine in the molecule. Instantaneous Dipoles Many small molecules do not possess permanent dipoles because the atoms that are bonded together all have the same, or very similar, electronegativity. This means that on average, the shared electron cloud is evenly distributed across the atoms.
To study the action of a buffer solution
EXPERIMENT ( 14 ) Topic : To study the action of a buffer solution Introduction : In this experiment, you are to compare the effects of adding small amounts of acid and alkali to buffered and unbuffered solutions of the same pH. You are provided with a buffer solution designed to maintain a pH of 7.0 at 25OC and some pure water which, if it is pure enough, should also have a pH of 7.0 at 25OC. To samples of these 2 liquids, you add small measured amounts of 0.1M NaOH and 0.1M HCl, measuring the pH at each addition. By comparing the pH changes in the 2 solutions, you can demonstrate the action of a buffer solution. Chemicals : 0.1M HCl(aq) , 0.1M NaOH(aq) , Distilled water , Buffer solution (pH 7.0) , Pure water (freshly-boiled distilled water) Procedures : Part A : Effect of NaOH on pH of buffer solution (pre-set at pH 7) . Fill a burette with 0.1M NaOH. 2. Using a measuring cylinder, put 25 cm3 of the buffer solution in a 50 cm3 beaker. 3. Rinse the pH meter electrode with distilled water from a wash-bottle, and put it into the beaker, making sure that the glass bulb is completely immersed. Set the meter to read 7.0 . 4. Place the beaker under the burette containing NaOH and, making sure the alkali does not fall directly on to the electrode, add 1 drop of 0.1M NaOH. Stir gently to ensure thorough mixing & record the pH in Table 1. 5. Add more NaOH to make
Determination of Total Hardness in Water by EDTA Titration
Principles of Environmental Chemistry Experiment 3: Determination of Total Hardness in Water by EDTA Titration Introduction Hardness of water is caused by divalent and multivalent metal that mainly came from contacting with the soil and rock formations. Hardness values are normally expressed in an equivalent amount of CaCO3 in mgl-1. If the hardness of water is smaller than 75mg/l, then it is described as soft water. EDTA can form very stable complex with metal ions (e.g. Mg2+ & Ca2+). The equation: M2+ + Na2H2EDTA › MEDTA2- + 2H+ + 2Na+ In this practical, EDTA (i.e. ethylene diamine tetraacetic acid) is used to determine the hardness of a water sample. EDTA can form very stable complex with metal ions (e.g. Mg2+ & Ca2+) i.e. M2+ + Na2H2EDTA › MEDTA2- + 2H+ + 2Na+ EDTA is added from a burette to the hard water sample and form (MEBT)- complex. At the equivalence point, EDTA removes the metal ion from the (MEBT)- by forming the more stable(MEBTA)-2 complex and free EBT- molecule that is blue in color. The equation :(MEBT)- + NaH2EDTA › (MEDTA)-2 + 2 HEBT2-+ H+ + 2Na+ red-wine blue Consequently, the end-point changes from red-wine colour to blue colour. Objective To determine the total hardness in a sample of water by the EDTA titrimetric method Procedure Please refer to the lab manual Result Standardization of EDTA Solution
Determination of the formula of complex ion
Chemistry Experiment 31 (a) Title: Determination of the formula of complex ion (b) Objective: To determine the formula of complex formed between nickel (II) and EDTA (c) Theory: Nickel (II) ion (Ni2+) forms complex with water, murexide and EDTA [Ni(H2O)6]2+ + murexide ==> [Ni(murexide)6]4- + H2O [Ni(H2O)6]2+ + EDTA ==> [Nickel-EDTA complex] + 6H2O EDTA (HO2CCH2)2NCH2CH2N(CH2CO2H)2), being a polydentate ligand, is of higher strength than that of murexide and thus form complex more readily than murexide. Also, murexide, by experiment, form complex more readily than water. Therefore, by the principle of competitive complexing, in a mixture of aqueous nickel ions with EDTA and murexide added, complex are formed between nickel ions and EDTA instead of with murexide. Similarily complex are formed between nickel ions and murexide instead of with water. Below are the colours of the different species in this experiment. Species Colour EDTA Colourless Murexide Dark Purple Nickel-water complex Green Nickel-murexide complex Yellow Nickel-EDTA complex Pale Blue In order to determine the formula of the Nickel-EDTA complex [Ni(EDTA)y] where y is a positve interger, the mole ratio of the reaction between Ni and EDTA has to be determined. This can be done by titrating nickel(II) solution against EDTA with murexide as indicator. Initially the mixture in the conical flask
Equivalent cube test
Equivalent cube test Objectives: Determine equivalent cube compressive strength of the concrete. Acquire an appreciation of the relation between equivalent cube compressive strength and other strengths such as cube compression strength, flexural tensile strength and splitting tensile strength. Test to be conducted: Determine compressive strength using equivalent cube method on a part of the beam broken in flexural tensile strength test in accordance with BS1881: Part 119: 1983. Specimen: Broken portion of beam from flexural strength test. Apparatus: Equivalent cube strength test jig, compressive testing machine. Procedures: a. The broken portions of the beams selected for the compressive strength test shall be have a length not less than 50mm greater than the width of the beam, be free from cracks, chipped surfaces or other obvious defects within the length to be tested. b. Unless this test is carried out immediately after the flexural strength test on the beam, the broken portions should be returned to the curing tank until required. c. Place the broken portion of the beam in the test jig as per the sketch. d. Place the jig centrally in the compression test machine (no packing is to be used between the specimen and the auxiliary platens or between the compression machine platens and the auxiliary platens). e. Apply the load without shock and increased
An investigation into the behaviour of mono-di-tri protic acids with a pure metal.
Investigating advanced reaction rates. Aim In this investigation I will examine how certain variables affect the rate of reaction. In particular I will attempt to evaluate the orders of the reactions, and whether this order is confined to a certain concentration range, and also I will aim to approximate the activation energy through observing the effect of temperature on the rate of reaction. I will be using Magnesium (alkaline earth metal) during all of my reactions and a range of acids. For a successful outcome, careful planning must be undertaken, where preliminary work will be of key importance in determining quantities and ranges of reactants, and temperatures to use, as well as selecting the most appropriate apparatus and laboratory techniques to be used in the full investigation. Theory In this section I will explain the theoretical chemistry of the variables in my investigation, through my understanding of rates of reactions as well as the use of information from various sources including, books, the internet, and encyclopaedias which will be fully listed at the end of this project. The rate determining step of a chemical reaction is one which is the slowest, and it is this which is represented in a rate equation. The rate equation cannot be calculated from the balanced chemical equation, but has to be found through experimental
Fission and Fusion (Open Book paper 2008)
Discuss, with the use of examples, the main differences between ?- and ß-decay and explain how nuclear fission reactions differ from natural radioactive decay. The differences between alpha and beta decay ?-decay ß-decay Emitted particle Helium-4 nucleus, 2 protons and 2 neutrons, +2 charge, 4 amu [1] Electron (made from a neutron dividing into an electron and a proton), -1 charge, 0.00055 amu [1] Most common in Heavier elements (atomic number > 83) [1] Elements with a greater ratio of neutrons to protons (generally elements lighter than lead, atomic number < 82) [2] Example equations [3] 224Ra --> 220Rn + 4He 231Po --> 227Ac + 4He 238U --> 234Th + 4He 225Rn --> 225Ac + 0e- 40K --> 40Ca + 0e- 4C --> 14N + 0e- Table 1 - the differences between alpha and beta decay Sources [1], [2], [3] The differences between nuclear fission and natural radioactive decay In natural radioactive decay, an unstable isotope of an element decays into a different atom and an emission (alpha/beta particle, or energy in the case of gamma/? radiation). This is a spontaneous natural process with a random rate. Nuclear fission is also the splitting of a nucleus into two smaller parts, but each of these is an element in itself. Fission does not happen spontaneously; it requires a trigger. An unstable nucleus bombarded with a neutron will "elongate and divide itself like a liquid
Standardizing a Sodium Hydroxide (NaOH) Solution
Standardizing a Sodium Hydroxide (NaOH) Solution Aims: The aim of this practical is to prepare a NaOH solution, determine the Concentration of the NaOH solution accurately and precisely and calculate of unknown concentration from titration results. Introduction: (i) Concentration of solutions: Although there are many different units of concentration, the most commonly used unit among chemists is morality (M). Molarity is defined as the number of moles of solute per 1-L of solution. The main advantage of molarity as a unit of concentration is therefore the ease with which measurements of the volume of a solution can be combined with the molarity to determine the number of moles of the solute that are present to take part in a chemical reaction. (ii) Standardization: The process of using a known amount of one reagent to determine the concentration of another reagent is known as standardization. This will allow the experiment to be accurate determination of the concentration of NaOH solution, which is linked to standardized can be provide accurately help the experiment. The formula reacts with the OH of sodium hydroxide in exactly the same way as HCl. HKC8O4H4 + NaOH NaKC8O4H4 + H2O (iii) Acid-Base Titration and End Point Reactions between acids and bases that are dissolved in water occur almost instantaneously: they occur as fast as the two