1961 as the first desensitising toothpaste based on a strontium chloride formulation. About 20 years later‚ in 1980‚ Sensodyne toothpastes containing a new potassium nitrate formulation were launched. Besides being a leader in treating dentine hypersensitivity‚ the Sensodyne brand expanded in 2006 with the launch of Sensodyne Pronamel to help protect against the effects of dental erosion. Sensodyne is globally recognised as a specialist toothpaste for sensitive teeth. In addition to being a global
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examine a number of different chemical reactions and determine if they are exothermic or endothermic. Apparatus: • Test tubes {Around 10-12 in number} • Test-tube rack • Spatula • Digital thermometer { ± 0.1° C} • Digital balance {± 0.01 g} • Measuring cylinder {± 0.5cm³} • Different chemicals Introduction/Theory: Exothermic reactions are those reactions that release energy in the form of heat. Endothermic reactions need to absorb energy in the form of heat
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How reaction rate varies with sodium thiosulphate concentration Background information Sodium thiosulphate and hydrochloric acid are both colourless liquids‚ when the two reactants are reacted together they produce sulphur. The sulphur that is produced from the reaction changes the solution to yellow and cloudy‚ this is a precipitation reaction‚ where a two solutions react and a solid forms in the solution‚ the solid is said to precipitate out. Some reactions will occur quickly such as fireworks
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Thermochemistry: An Ice Calorimeter Determination of Reaction Enthalpy Curtis M. Franklin Thursday‚ February 14‚ 2013 ABSTRACT An ice calorimetric measurement was used to determine that a reaction involving solid magnesium metal and 1.00M sulfuric acid produces an experimental a value of ∆H = -226 ± 28 kJ/mol at 0°C. This is about 48.4% lower than the expected value reported at 25°C. Introduction Many chemical reactions exhibit themselves by exchanging heat energy‚ either be absorbing
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the temperature the faster the reaction will occur) has been proven correct and it proves the theory right. From the results‚ we can see this‚ as the iced water (10 degrees) had the slowest rate of reaction at 1.10 minutes. Then the room temperature water (19 degrees) was tested and had a slightly better rate of reaction at 1.09 minutes. Then last of all‚ we tested the boiling water (63 degrees) which had a large improvement from the last two with a rate of reaction of 43.5 seconds. This showing development
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How does the concentration affect the rate of a reaction? 30/1/2012 By Alex Whenman Contents page 1. Introduction to my investigation 2. Background information on concentration 3. What experiment I will be conducting 4. Equipment I will be using 5. How I will be conducting the experiment 6. Heath and safety risk assessment 7. What I think will happen 8. How I will set up my experiment 9. Why I’m having my experiment set out like
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Computerized Data Acquisition of a Second Order Reaction Abstract Introduction The rates at which reactions occur depend on the composition and the temperature of the reaction mixture. Usually the rate of reaction is found to be proportional to the concentrations of the reactants raised to a power.1 There are many reactions that have a rate law in the form of: (1) v = k[A]a[B]b According to reference1 the power to which the concentration of a species (product or reactant) is raised
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Determination of the activation energy of an enzyme catalysed reaction Introduction In this practical the aim for this experiment was to find out the catalytic power of alkaline phosphate‚ as well as the rate of reaction and the activation energy of p-nitrophenol phosphate. Enzymes are biological molecules that catalyse a chemical reaction. ‘Enzymes work by lowering the activation energy of a chemical reaction making it easier to proceed’ [1]. This allows molecules to have more energy therefore
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For known amounts of reactants‚ theoretical amounts of product can be calculated in a chemical process. These calculated products are determined using the limiting reagent‚ (the substance that runs out first which stops the reaction) and are called the theoretical yield. The theoretical yield is the amount of product that should be acquired during the experiment if all aspects go perfectly. However‚ due to experimental errors‚ very few labs do so. These results are called actual yield. The percent
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The hypothesis was supported by graph 3 and 6 which both showed that an increase in concentration of the reacting species resulted in an increase in reaction rate. Both graphs have a positive gradient which clearly indicates that concentration increases the reaction rate. The hypothesis also proposed that as temperature increases the speed of the reaction would decrease‚ this is evidenced in graph 7 which shows a negative decrease in time as the temperature of the solution increases. This decrease can
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