Rates of Reaction

Rate of Reaction Experiment Introduction: 8C conducted an experiment to investigate the four factors which affect rates of reaction (temperature, concentration, surface area and the addition of a catalyst.) In this case, we examined the impact concentration has on the rate of reaction. We combined three samples of one type of mixture, but of varying concentrations of the solvent. Unfortunately, due to some human error we were unable to complete the experiment but have detected various indicators which supported our hypothesis. Our observations were recorded in a table intended for what would have been our quantitative data. AIM: To investigate the effect of concentration on the rate of reaction HYPOTHESIS: I hypothesize that the rate of reaction would be accelerated by a greater concentration of solutes. When more solute has been added, there are more particles in the same volume to react with one another, as demonstrated in the adjacent diagram. NOTE: A chemical reaction involves the collision between particles. The particles collide to generate a new substance(s). Fewer particles mean less chance of collision. Independent Variable (x): the concentration of one reactant (in this case, the hydrochloric acid.) Dependent Variable (y): the rate of reaction (i.e. the time it takes for the chemical process to be complete.) Controlled Variables: * The volume of the

  • Word count: 1388
  • Level: AS and A Level
  • Subject: Science
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Rates of reaction

Rates of Reaction Introduction- Rates of reactions are how fast a reaction occurs. The factors that have an impact on the rate of the reaction are temperature, surface area, catalyst and concentrations. Temperature has an impact as when two chemicals react, their molecules have to collide with each other, and by heating the mixture you will be supplying high amounts of energy which will speed up the reaction. This is kinetic theory. Surface area has an impact on rate of the reaction as If one of the reactants is a solid, the surface area of that solid will affect how fast the reaction is, and this is because the two types of molecule can only bump into each other at the liquid solid interface. So the larger the surface area of the solid, the faster the reaction will be. Concentration has an impact as increasing the concentration of the reactants will increase the rate of collisions between the two reactants. This is collision theory. This is because the molecules in the reaction mixture have a range of energy levels. When collisions occur, they do not always result in a reaction. If the two colliding molecules have sufficient energy they will react. Aim: To investigate the effect of surface area on the rates of reaction. Hypothesis: I predict that when the surface area increases the reaction time will increase, this is because when we make pieces of a reactant smaller we

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  • Level: AS and A Level
  • Subject: Science
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Analysis of commercial vitamin C tablets

Analysis of commercial vitamin C tablets Objective To determine the vitamin C content in commercial vitamin C tablets by titration between vitamin C (ascorbic acid) & iodine solution. Hence, compare this data with the manufacturer's specification. Principle In this analysis, certain amount of iodine solution, which is known in excess, is added to acidified ascorbic acid solution. Brown iodine can be easily reduced by acidified ascorbic acid to form colourless iodide ion: ‹ Equation I The excess iodine is then back titrated by standard sodium thiosulphate solution, by using a burette and starch solution (used as end point indicator) Similarly, iodine can also be decolourized by thiosulphate ion: 2S2O32- + I2 › S4O62- + 2I- ‹ Equation II Any iodine present will react with starch to form a blue-black complex. However, when all available iodine has been reacted, the blue-black complex becomes colourless which signals the end-point. Hence, the mass of ascorbic acid reacted by iodine can be calculated. Chemicals vitamin C tablet(s), NaIO3, 1M NaI solution, 0.5M H2SO4, approximately 0.06M Na2S2O3, freshly prepared starch solution Apparatus electronic balance, beaker, volumetric apparatus, pipette, glass rod, white tile, dropper, measuring cylinder Procedure 1.> Accurately weigh 0.6 to 0.7g sodium iodate, NaIO3 and

  • Word count: 1942
  • Level: AS and A Level
  • Subject: Science
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Analysis of Commercial Vitamin C Tablets

EXPERIMENT ( 1 ) Topic : Analysis of Commercial Vitamin C Tablets Introduction : In this experiment the vitamin C content of commercial tablets is determined titrimetrically and compared with the manufacturers' specifications. Vitamin C is ascorbic acid which is rapidly and quantitatively oxidized by iodine in acid solution according to the following equation : C6H8O6(aq) + I2(aq) --> C6H6O6(aq) + 2 H+(aq) + 2 I-(aq) The standard method for determination of ascorbic acid involves the direct titration of the acidified sample with a standard iodine solution. But the low solubility of iodine makes this procedure less than ideal. The proposed experiment avoids these difficulties by generating in situ a known excess quantity of iodine by the reaction between iodate(V) & iodide : IO3-(aq) + 5 I-(aq) + 6 H+(aq) --> 3 I2(aq) + 3 H2O(l) After reacting with ascorbic acid, the remaining iodine may then be titrated against standard sodium thiosulphate solution. Chemicals : Vitamin C tablets , 0.05 M Na2S2O3 , 0.5 M H2SO4 , 1 M KI , KIO3 , Starch solution (freshly prepared) Procedures : 1. Accurately weigh out 0.6 to 0.7g of potassium iodate(V). Record the mass.. 2. Dissolve this in deionized water and make up to 250 cm3 in a volumetric flask. 3. Use such iodate(V) solution to standardize the given thiosulphate solution as follows : (a) Pipette 25.0 cm3 of

  • Word count: 1114
  • Level: AS and A Level
  • Subject: Science
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Analysis of Sulphur Dioxide Content in Wine

EXPERIMENT ( 3 ) Topic : Analysis of Sulphur Dioxide Content in Wine Introduction : In the presence of atmospheric oxygen, the alcohol content of wine can be converted to ethanoic acid making the wines sour & unpalatable. Even small amount of air, over a period of time, can adversely affect wines. The problem can be minimized by the introduction of a suitable reductant which will preferentially react with oxygen. One such reductant is sulphur dioxide but because it is toxic & pungent in odour, limits are set on the amount of "free" sulphur dioxide allowed in wine. Most of the preservative present in wine is "fixed" in the form of NaHSO3. Although this can act as a source of sulphur dioxide, the actual amount of free sulphur dioxide is quite low. In this experiment, the amount of total available SO2 in the wine, irrespective of its actual form in the sample is determined. The method involves first the conversion of all SO2 into SO32-. Acidification of the solution then liberates all SO2 : SO32-(aq) + 2 H+(aq) --> SO2(aq) + H2O(l) SO2 is then titrated with iodine solution : SO2(aq) + I2(aq) + 2 H2O(l) --> 2 HI(aq) + H2SO4(aq) Chemicals : White wine (non-sparkling or non-carbonated), 1M NaOH , 2M H2SO4 , 0.005M I2 , KIO3 , Starch solution (freshly prepared) Procedures : 1. Determine, from the label, the volume of wine in a bottle. 2. Using a pipette,

  • Word count: 723
  • Level: AS and A Level
  • Subject: Science
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Analysis of two Commercial Brands of Bleaching Solution

Experiment 4 Analysis of two Commercial Brands of Bleaching Solution Objective To determine the concentrations of the active ingredients in 2 commercial bleaches. Introduction Sodium hypochlorite is usually found in bleaching solutions. It is the active ingredient of bleaching solutions. It bleaches by oxidation. When it is added to dye, the following reaction occurs: ClO- + dye ----------------> Cl- + (dye + O) If the oxidized form of the dye is colorless, then the color of the dye would fade away. In the presence of acid, the hypochlorite ions from the bleaching solution reacts with the iodine ions from potassium iodide in the following way: ClO- + 2I- + 2H+ --------->I2 + H2O + Cl- When sodium thiosulphate solution is added into this reacted solution, a further reaction occurs: I2 + 2S2O32- -------------->2I- + S4O62- This reaction could be used in titration to find out the number of moles of thiosulphate ions, thus the concentration of hypochlorite ions in the bleaching solution. Procedure . 10 cm3 of Kao Bleach was pipette into a volumetric flask. Distilled water was added until the meniscus reaches the graduation point. 2. 25 cm3 of the titrated bleach was pipette into a conical flask. About 10 cm3 of potassium iodide and dilute sulphuric acid was added into the conical flask. 3. The solution was titrated with sodium thiosulphate solution until the

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  • Level: AS and A Level
  • Subject: Science
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Enthalpy change of a displacement reaction

Chemistry TAS Report . Experiment Number : 4 2. Date : 15/10/07 3. Title : Enthalpy change of a displacement reaction 4. Aims/Objective : To determine the enthalpy change of a displacement reaction (Between zinc and copper (II) ions) 5. Introduction : Excess zinc powder is added in a measured amount of aqueous copper (II) sulphate. The temperature change is then measured over a period of time so the enthalpy of this reaction can be calculated. 6. Relevant Equations/Chemical Reactions Involved : Zn (s) + CuSO4(aq) ?? ZnSO4(aq) + Cu(s) 7. Chemicals : 1.00M copper (II) sulphate solution 25.0 cm3 Zinc powder (in excess) 5.9g 8. Apparatus and equipment : Safety spectacle x 1 Spatula x 1 25 cm3 pipette x 1 Balance x 1 Pipette filler x 1 Thermometer(0-100 oC) x 1 Polystyrene cup with lid x 1 Digital timer x 1 Weighting bottle x 1 9. Procedure : 1. An empty polystyrene cup was weighted. 2. 5.9g of zinc powder (in excess)was weighted and then added into the polystyrene cup. 3. The temperature of the copper (II) sulphate solution in beaker was recorded every half minute for 2.5 minutes and then 25.0 cm3 of the copper (II) sulphate solution was pipetted into a polystyrene cup. 4. Thermometer was put through the hole of the lid. The solution

  • Word count: 590
  • Level: AS and A Level
  • Subject: Science
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Thermometric Titration

CHEMISTRY COURSEWORK (II) THERMOMETRIC TITRATION by Andrew McLorn Planning Normally we use an indicator when doing titration experiments, in this experiment we will not be using an indicator. Instead we will be monitoring the temperature of the solution. When an alkali is mixed with an acid heat is given out, this is called an exothermic reaction. The temperature goes up until the acid is neutralised and then no more heat is given out because the reaction is over. Adding more alkali causes the temperature to decrease. Apparatus .retort stand and clamp .burette .pipette .small beaker containing HCl .small beaker containing NaOH .funnel .polystyrene cup thermometer Method )collect apparatus 2)pipette 25cm3 of acid 3)put the acid in to the polystyrene cup 4)fill burette with NaOH 5)put thermometer in polystyrene cup and note temperature 6)add 5cm3 of NaOH, stir the solution and note temperature 7)keep adding NaOH at 5cm3 intervals, stir and note temperature between each addition of NaOH Displaying the Results Results should be displayed in a graph and a table like the one shown below: Safety The following safety precautions should be observed when carrying out this experiment: .assemble apparatusin the centre of an uncluttered bench .take care as acid is being used .wear goggles Conclusion As expected, the temperature of the solution increased

  • Word count: 414
  • Level: AS and A Level
  • Subject: Science
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Who’s Cheating on the Vinegar?

Who's Cheating on the Vinegar? Vinegar is an ethanoic acid. A wholesaler supplies chip shops. Design an investigation which identifies which chip shops are watering down the vinegar. Background Theory All acids contain the element "hydrogen". Water ionises the hydrogen to make it H+. To react all acids have to be ionised. Strong acids are almost completely ionised and weak acid are only partially ionised, which is why they don't react as much as strong acids. The pH of any acid would be below 7 (neutral), ranging from 1 (strong acid) to 6 (weak acid). Anything above 7 is an alkali, pH 14 being a strong alkali and pH 8 being a weak alkali. In titration we add alkali to the acid until the mixture neutralises. We use an indicator to tell us at which point the neutralisation occurs. When we have this information we can find the concentration of the acid using the calculation concentration = moles dm³ The acid we are using in this experiment is ethanoic acid (vinegar). It is a weak acid and is only partly ionised. This is an organic acid. In an ionised acid the following process has occurred: HCl --> H+ Cl- (using hydrochloric acid as an example) In this investigation we have taken 5 different acids, one being used by a chip shop (acid A), to test which one is the most concentrated and which one is the most dilute (watered down) by

  • Word count: 615
  • Level: AS and A Level
  • Subject: Science
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