18.1.4 – 18.1.6 CALCULATIONS INVOLVING ACIDS AND BASES Review of Important formulas pH = ‐ log10[H+] [H+] = 10‐pH pKa = ‐ log10 Ka Ka = 10‐pKa pOH = ‐ log10[OH‐] [OH‐] = 10‐pOH pKb = ‐ log10 Kb Kb = 10‐pKb The ionic product of water = Kw = [H+] x [OH‐] = 1.0 x 10‐14 mol2 dm‐6 at 298 K The expression varies with temperature
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EXPERIMENT 2: Recrystallization and Melting Point Recrystallization (or Crystallization) is a technique used to purify solids. This procedure relies on the fact that solubility increases as temperature increases (you can dissolve more sugar in hot water than in cold water). As a hot‚ saturated solution cools‚ it becomes supersaturated and the solute precipitates (crystallizes) out. In a recrystallization procedure‚ an impure (crude) solid is dissolved in a hot solvent. As this solution is cooled
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KINETICS OF THE ACID DECOMPOSITION OF THIOSULFATE Aqueous solutions of thiosulfate‚ S2O32-(aq) are stable if neutral or basic‚ but decompose quickly when the thiosulfate is dissolved in acid according to the equation: Sulfur dioxide is a gas at room temperature‚ but is very soluble in water. Sulfur‚ a water insoluble solid‚ forms a colloidal suspension. As a result‚ the solution first becomes cloudy and then opaque. We can take advantage of the developing opacity of the reaction system to do a
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Chemical Reactions and Equations Chemical Reaction: The transformation of chemical substance into another chemical substance is known as Chemical Reaction. For example: rusting of iron‚ setting of milk into curd‚ digestion of food‚ respiration‚ etc. In chemical reaction new substance is formed which is completely different in properties from the original substance‚ so in a chemical reaction chemical change takes place. Following are the signs of chemical reaction: (a) Change of state of substance
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Acid Rain Acid rain occurs when Sulphur Dioxide (SO2) is released into the atmosphere by electricity generation‚ motor vehicles‚ factories and by wildfires and volcanoes. Once released‚ the sulphur dioxide reacts with water to produce sulphuric acid. This has a pH of approximately 2-3 pH. This has a dramatic effect on water dwelling wildlife. Most water dwelling creatures can’t withstand water more acidic than pH 5. This causes the mass loss of life of animals such as trout‚ perch‚ frogs and mayflies
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CHAPTER 1 Introduction Background of the Study Like many other hygiene convenience‚ shoe polish or can also be called boot polish is usually a wax ‚ cream or paste used by people to shine‚ water proof and restore the appearance of leather shoes. This extends the footwear’s life. This is made up of many kinds of chemicals and because of this; it can cause irritations‚ allergies to us. In our generation‚ shoe polish is used every day and companies produce a lot of it to meet the demands of
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Acid-Base Extraction: Separation of an Organic Acid‚ Base and a Neural Compound Introduction/Background Acid base extraction is a widely used commercial method in separating acids‚ bases and neutral compounds. This is concept is based on several physical properties of the compounds‚ such as boiling point‚ melting points and solubility. The different solubility properties of the protonated and non-protonated forms of these compounds depend on the functional groups present‚ such
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Purpose: To determine the percent magnesium by mass in magnesium oxide and to observe if the percentage composition is constant by comparing class results. Hypothesis/Prediction: The percent composition by mass of magnesium in magnesium oxide will not change significantly with each group that conducted the experiment. The composition of each substance should stay the same and any differences must be due to some error. Materials:Magnesium stripCrucibleCrucible coverClay triangleIron ringRetort standTongsBalanceBunsen
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Chemical Reactions Lab Objectives: 1. To examine a variety of reactions including precipitation‚ acid-base‚ gas forming‚ and oxidation-reduction reactions. 2. To identify the products formed in these reactions and summarize the chemical changes in terms of balanced chemical equations and net ionic equations. 3. To identify the species being oxidized and reduced in oxidation-reduction reactions and determine which species is the oxidizing agent and the reducing agent. Chemical equations represent
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solution will turn colourless and it will take a specific time for the reaction to complete. By increasing the temperature‚ the time it takes (the rate) for the solution to completely change to colourless will be increased. Thus it can be said‚ that it is being hypothesized that an increase in temperature will cause an equal increase in the rate of the reaction. Method:1). Using a measuring cylinder‚ place 50 cm3 of sulphuric acid into a 250 cm3 beaker‚ add 50 cm3 of water using the same measuring
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