Energy and Rates Analysis of Chemical Reactions
Name: Alec Cooke Partners: Erik MacPherson and Ben Murat Experiment Date: November 6th 2008. Lab 3: Energy and Rates Analysis of Chemical Reactions Due Date: November 17th 2008. Instructor: Mr. MacLean Questions (i) How does the molar enthalpy of reaction of magnesium vary with different acids, namely, hydrochloric, sulfuric, and acetic acids? (ii) How does the rate of reaction of magnesium vary with these acids? Hypothesis If magnesium is mixed into any of the aqueous acid solutions, it is predicted that there will be fizzing and bubbling. This bubbling will be due to the release of Hydrogen gas, which is produced when the hydrogen bonds are broken and replaced with the magnesium. It is hypothesized that the test tubes will be warm, because the reaction is exothermic; therefore it releases energy, or heat into its surroundings. It is also expected that the carboxylic acid (Ethanoic acid) will have a faster rate of consumption for magnesium, because its carbon base will allow it to let go of its hydrogen atoms more readily than hydrochloric and sulfuric acid. The molar enthalpy for Magnesium should only vary because of human error. All three calculated enthalpies should be very close, because the molar enthalpy of Magnesium is dependant upon only Magnesium's properties, not the other reactants'. Materials * 1 mol/L Aqueous Ethanoic acid * 1 mol/L Aqueous
Acid Content of Vinegar
Acid Content of Vinegar Aim: -To determine the concentration of ethanoic (acetic) acid in a sample of vinegar. Apparatus: As per prac sheet Method: As per prac sheet Safety: Results: Morrow Vinegar- Titration repeat Initial reading Final Reading Titre 2.45ml 31.59ml 29.14ml 2 4.01ml 33.52ml 29.51ml 3 4.32ml 34.02ml 29.70ml Aceto Vinegar- Titration repeat Initial reading Final Reading Titre 2.32ml 28.90ml 26.58ml 2 0.77ml 28.23ml 27.46ml 3 3.71ml 29.19ml 25.48ml Cornwalls Vinegar- Titration repeat Initial reading Final Reading Titre 3.35ml 23.41ml 20.06ml 2 4.13ml 24.80ml 20.67ml 3 3.65ml 24.31ml 20.66ml Questions: ) Calculate the mass of ethanoic acid in each sample of vinegar. The mass of ethanoic acid in the sample of Morrow vinegar is: 0.1767g n(NaOH) = c × v = 0.1 × 0.02945 n = 0.002945 mol n(CH3COOH) = 0.002945 mol (n(NaOH) and n(CH3COOH) are a 1:1 ratio) m = n mr mass(CH3COOH) = 0.002945 × 60 = 0.1767 grams The mass of ethanoic acid in the sample of Aceto vinegar is: 0.15906g n(NaOH) = c × v = 0.1 × 0.02651 n = 0.002651 mol n(CH3COOH) = 0.002651 mol m = n mr mass(CH3COOH) = 0.002651 × 60 = 0.15906 grams The mass of ethanoic acid in the sample of Cornwalls vinegar is: 0.15906g n(NaOH) = c × v = 0.1 × 0.02046 n = 0.002046 mol n(CH3COOH) = 0.002046 mol m = n mr mass(CH3COOH) =
Objective: The purpose of this experiment is to determine the composition of a mixture of solutions of NaOH and Na2CO3 by double indicator method.
Experiment 4: Acid-base Titration using Method of Double Indicators Date: 2010/10/7 I. Objective: The purpose of this experiment is to determine the composition of a mixture of solutions of NaOH and Na2CO3 by double indicator method. II. Introduction: Consider a mixture of NaOH(aq) and Na2CO3(aq). Reaction between HCl(aq) and Na2CO3(aq) takes place in two stages: HCl(aq) + Na2CO3(aq) › NaHCO3(aq) + H2O(l) -------------------------(1) HCl(aq) + NaHCO3(aq) › NaCl(aq) + CO2(g) + H2O(l) -----------------(2) While that between HCl(aq) and NaOH(aq) completes in only one step: HCl(aq) + NaOH(aq) › NaCl(aq) + H2O(l) -----------------------------(3) The hydrochloric acid is placed in the in the burette and is added, slowly and with constant swirling, to the mixture of NaOH(aq) and Na2CO3(aq). Solution mixture of reaction (1) at the equivalence point is alkaline, while that of reaction (2) is acidic and that of reaction (3) is neutral. Therefore the whole titration should have three breaks in the pH curve, corresponding to the above three stages. Reactions (1) and (3) can be indicated by phenolphthalein and that of reaction (2) can be indicated by methyl orange. III. Procedure: . All apparatus should be rinsed properly with corresponding solution 2. 25cm3 of the mixture of NaOH(aq) and Na2CO3(aq) was pipetted into conical flask. 3. Burette was filled with
Experiment to determine the ethanol content of wine
Experiment to Determine Ethanol Content of Wine The purpose of this experiment is to determine the ethanol content of each of the wines and compare the value determined to the value quoted on the label. These results can then be used to conclude which region is more accurate in quoting the value of the ethanol content of the wine. This experiment takes advantage of the fact that ethanol is less dense than water in solution. The density of ethanol at 20°C is 0.789 g/cm3 while the density of water at the same temperature is 0.998 g/cm3. It then follows that different solutions of ethanol and water will have different densities also, because the relative volume of ethanol increases and water decreases so the density of higher percentage ethanol solutions will be less than the density of lower percentage ethanol solutions. This occurs because water molecules are much smaller than ethanol molecule, meaning more water molecules can "pack" into a smaller volume than ethanol molecules, meaning there is more mass per unit volume of water compared to ethanol, meaning it has a higher density. In this experiment, solutions of ethanol in water were made up, going from 0% to 20%. These were then weighed, and the density of the ethanol was calculated. From this, a graph of percentage ethanol solution against density was made. This graphs later compared to the density of the wine, so
Equilibrium Constant for esterification
Chemistry Experiment 15 (a) Title: Equilibrium Constant for esterification (b) Aim: To find out the equilibrium constant for esterification of ethanoic acid and propan-1-ol. (c) Theory: In the presence of conc. H2SO4 and under reflux, ethanoic acid undergoes a reversible reaction with propan-1-ol to form ester and water. As equilibrium is reached, CH3COOH(l)+CH3CH2CH2OH(l) CH3COOCH2CH2CH3(l)+H2O(l) Kc = By titrating the reaction mixture with standard alkali solution before and after refluxing, the quantity of the acid used, and thus the quantities of the alcohol used as well as of the ester and water formed can be determined. Knowing the quantities or molar concentrations of the species present in the equilibrium mixture, the equilibrium constant, Kc can be calculated. Set-up: (d) Result: Titration of 8 drops of H2SO4 against NaOH Titration (trial) 2 Final burette reading (cm3) 5.1 30.2 Initial burette reading (cm3) 0 5.1 Volume of NaOH used (cm3) 5.1 5.1 Titration of final reaction mixture against NaOH Titration (trial) 2 Final burette reading (cm3) 8.2 6.0 Initial burette reading (cm3) 0.0 8.2 Volume of NaOH used (cm3) 8.2 7.8 No. of moles of CH3COOH in 1 cm3 of reaction mixture before heating = [(density x volume) / molar mass] / volume = [(1.05 gcm-3 x 15 cm3) / (12x2+1x4+16x2)] = 8.75 x 10-3 mol 2 NaOH + H2SO4 Na2SO4 + 2
Fertiliers organ Vs inorganic
Fertiliers organ Vs inorganic To make sure we use our land efficiently to get as much growth from it as we can, we have chemicals such as pesticides and fertilizers to make sure farmers harvest a maximum yield each year, but how much do we know about these chemicals? There are two main types of fertilizers, organic and inorganic. Organic fertilizers are organic materials, mainly made of animal and plant wastes. Inorganic fertilizers are concentrated source of macronutrients. They are usually in powdered form, which can be added directly into the field. First of all, let us consider the advantages of using organic fertilizers. Organic materials can be made by farmers themselves as they can be produced from waste materials from cattle, i.e. from cow manure. Sometimes, farmers can fertile their land by having a mixed farm (gazing animals and growing crop at the same land). Animal waste can be applied to plant crops, making soil more fertile. This can also save farmers money to purchase chemical fertilizers elsewhere. Unlike inorganic fertilizers, organic fertilizers do not damage soil structure; they can help to reduce soil erosion by improving the soil structure such as the water-holding properties. Improving the water-holding capacity of the soil also gives a distinct advantage to areas that have arid climates. As a result of improving the soil structure of lands, it
Preparation of propanone from propan-2-ol
Date: 11/10/2011 Exp. No.: 23 Title: Preparation of propanone from propan-2-ol Aim: The aim of this experiment is to prepare propanone by oxidizing propan-2-ol with acidified potassium dichromate solution. Introduction: Ketones and aldehydes are important series in preparation of other compounds and they are commonly prepared by oxidizing alcohol which is done in this experiment. The experiment is an oxidation reaction where a secondary alcohol (propan-2-ol) is oxidized by acidified potassium dichromate. The reaction does not need to be heated but should be placed in an iced water bath as the reaction is highly exothermic. The product is propanone and no catalyst is needed for the reaction. The propanone is serparated from the reaction mixture by simple distillation and is purified using anhydrous cacium chloride. The equation of this reaction is as follow: Chromic acid is produced in situ by adding potassium dichromate (VI) with sulphuric acid and water. K2Cr2O7 + H2O + 2H2SO4 ? 2 H2CrO4 + 2 NaHSO4 The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. Chromic acid features chromium in an oxidation state of +6. It is a strong and corrosive oxidising agent. Apparatus and chemicals: Apparatus: Quick-fit distillation setup,
Analysis of 2 commercial brands of bleaching solution & a determination of the best buy
EXPERIMENT ( 2 ) Topic : Analysis of 2 commercial brands of bleaching solution & a determination of the best buy Introduction : Sodium chlorate(I) forms the basis of most commercial bleaches. The amount present in bleaching solution can be determined by a volumetric technique. In this experiment, sodium chlorate(I) reacts with excess potassium iodide in the presence of acid to liberate. The iodine is titrated against standard sodium thiosulphate solution. Chemicals : Bleach solution , 0.1 M Na2S2O3 ,1 M H2SO4 , KI , Starch indicator Procedures : 1. Determine the total volume of bleach in the commercial bottles provided. Note the brand name, volume & price of each sample. 2. Pipette 25 cm3 bleach solution into a 250 cm3 volumetric flask. Make up to the mark & mix well. 3. Pipette 25 cm3 of this solution into a conical flask. Add 10 cm3 KI solution & 10 cm3 1 M sulphuric acid. 4. Titrate this mixture against the standard sodium thiosulphate solution provided. Add starch indicator when the solution become pale yellow. 5. Record your results and calculate the molarity of the orginal bleach solution. 6. Determine which bleach has the lowest price per mole of actual bleach. Results : Brand A = ___________KAO_____________ Brand B = _________Best Buy____________ Volume = ___________1.5L______________ Volume = ____________2L_______________ Price = _______$12.9 /
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
Chemistry Module 1 revision notes - salts and redox reactions
Chemistry Module 1 Salts - A salt is an ionic compound with the following features: The positive ion or cation in a salt in a salt is usually a metal ion or an ammonium ion NH4 The negative ion or anion in a salt is derived from an acid Formation of Salts: Salts can be produced by neutralising acids with: - Carbonates - Bases - Alkalis Salts from bases: Acids react with bases to form a salt and water Salts from Carbonates: Acids react with carbonates to form a salt, CO2 and water Salts from alkalis: Acids react with alkalis to form a salt and water Salts from metals: Salts can be formed from the reaction of reactive metals with acids. There are known as redox reactions. Ammonia salts and fertilises: - Ammonia salts are used as artificial fertilisers - Ammonia salts are formed when acids are neutralised by aqueous ammonia Water of crystallisation -Water of crystallisation refers to water molecules that form an essential part of the crystalline structure of a compound. Often the compound cannot be crystallised if water molecules are not present. -The empirical formula of a hydrated compound is written in a unique way: -The empirical formula of the compound is separated from the water of crystallisation by a dot. - The relative number of water molecules of crystallisation is shown after a dot. Oxidation number: in a chemical formula each atom has an
