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

  • Word count: 1163
  • 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

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  • Level: AS and A Level
  • Subject: Science
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Enthalpy changes

Enthalpy Changes Analysis Results Recording Test 1 Test 2 Test 3 Units Mass of CaCO3 + weighing bottle 3.50 3.52 3.50 g Mass of empty weighing bottle .04 .01 .00 g Mass of CaCO3 used 2.50 2.50 2.50 g Temperature of acid initially 21.50 22.00 21.00 °C Temperature of solution after mixing 24.00 24.00 23.00 °C Temperature change during reaction 2.50 2.00 2.00 °C Mass of CaO + weighing bottle 2.52 2.30 2.40 g Mass of empty weighing bottle .12 0.90 .00 g Mass of CaO used .40 .40 .40 g Temperature of acid initially 22.00 22.50 21.00 °C Temperature of solution after mixing 32.50 32.50 30.00 °C Temperature change during reaction 0.50 0.00 9.00 °C ?H1 The Reaction between CaCO3 + HCL J = m.c. ?T is used to calculate the energy produced using heat capacity of HCL, and 50ml of HCL with the temperature change in the reaction. J = m.c. ?T 50 x 4.2 x 2.5 = -525 J 50 x 4.2 x 2 = -420 J 50 x 4.2 x 2 = -420 J AVG = -455 J moles = mass 2.5 = 0.025 molar mass 100 ?H1 = -18.22 units = kJ/mol ?H2 The Reaction between CaO + HCL J = m.c. ?T is used to calculate the energy produced using heat capacity of HCL, and 50ml of HCL with the temperature change in the reaction. J = m.c. ?T 50 x 4.2 x 10.5 = -2205 J 50 x 4.2 x 10 = -2100 J 50 x 4.2 x 9 = -1890 J AVG

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  • Level: AS and A Level
  • Subject: Science
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Esters investigation.

Esters Esters are compounds formed from the reaction between alcohols and acids. Esters are usually derived from carboxylic acids A carboxylic acid contains the -COOH group, and in an ester, the hydrogen in this group is replaced by a hydrocarbon group of some kind. This could be an alkyl group like methyl or ethyl, or one containing a benzene ring like phenyl. Example of esters: ATP, it is a phosphate ester. Fats and oils. Fats and oils are tri-esters of glycerol, propane 1, 2, 3 triol, with carboxylic acids Glycerol Fats usually come from land animals e.g. butter. Oils usually come from marine animals and from the vegetable kingdom e.g. sunflower oil. The difference between a fat and oil is simply in the melting points of the mixture of esters they contain. If the melting points are below room temperature, it will be a liquid - oil. If the melting points are above room temperature, it will be a solid - a fat. The lower melting temperature oils tend to replace fats in marine animals e.g. whales, because fats would be too viscous or solid at sea temperatures. Fats contain mainly saturated acids such as: * Hexadecanoic acid: C15H3CO2H, which is commonly known as palmitic acid. CH3 (CH2)14 COH * And octadecanoic acid: C17H35CO2H, which is commonly known as stearic acid. CH3 (CH2)16CO2H While oil contains a high proportion of unsaturated acids such

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  • Level: AS and A Level
  • Subject: Science
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Investigate the enthalpy values for the reaction between calcium carbonate and calcium oxide with Hydrogen Chloride.

Investigate the enthalpy values for the reaction between calcium carbonate and calcium oxide with Hydrogen Chloride. Chemistry coursework Aim I will carry out this practical to investigate the enthalpy values for the reaction between calcium carbonate and calcium oxide with Hydrogen Chloride. I will collect the results and analyse them to reach a conclusion about the reactions between the reactants. Theory I will measure the temperature changes when calcium oxide and calcium carbonate react with hydrochloric acid solution. I can use a Hess' Law cycle to calculate the enthalpy changes using the equation. Enthalpy change = mass of liquid x temperature change x specific heat capacity This equation will help me to calculate the enthalpy changes, and which reaction was more exothermic, and why. I drew a Hess' Law cycle to illustrate the enthalpy values. CaCO³ (s) CaO (s) + CO² (g) H¹ H² H³ CaCl² (aq) Fair test · We used scales correct to 2 decimal places. · We measured the calcium oxide and calcium carbonate straight into the beaker to avoid leaving particles on the paper I would otherwise have measured it on. · We measured the hydrochloric acid using a measuring cylinder including the meniscus to make it accurate, and poured out as much as possible. We couldn't wash it out and this would have affected the concentration of the acid and the rate of

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  • Level: AS and A Level
  • Subject: Science
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Investigation of Some of the Properties of a Pair of Cis-Trans Isomers

Experiment18 Aim To determination the partition coefficient of ethanoic acid between water and butan-2-ol. Procedure . The room temperature was recorded. 2. 15cm3 of the given aqueous ethanoic acid and 15cm3 of butan-2-ol were poured into a 100cm3 separating funnel, using suitable apparatus. The funnel was stoppered and was shook vigorously for 1 to 2 minutes. (The pressure in the funnel was released by occasionally opening the tap.) 3. 10cm3 of each layer was separated approximately. (The fraction near the junction of the two layers was discarded.) 4. 10.0cm3 of the aqueous layer was pipetted into a conical flask and was titrated with 0.1 M sodium hydroxide solution using phenolphthalein. 5. Using another pipette, 10.0 cm3 of the alcohol layer was delivered into a conical flask and was titrated with 0.1 M sodium hydroxide solution. 6. Steps (2) to (5) was repeated with another separating funnel using the following volume: 25cm3 of aqueous ethanoic acid and 15cm3 of butan-2-ol 7. For each experiment, the ratio of the concentration of ethanoic acid in the aqueous layer to that in the butan-2-ol layer was calculated. Result Room temperature: 29? Volume of butan-2-ol: 15 cm3 Volume of 0.2M ethanoic acid / cm3 Volume of 0.1M NaOH titre for aqueous layer / cm3 Volume of 0.1M NaOH titre for alcohol layer / cm3 Partition coefficient K= 5 0.00 2.55 0.796 25

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  • Level: AS and A Level
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Scientific Practical Techniques

BETC National Diploma in Applied science/ Medical Science Scientific Practical Techniques Assignment number one Task 2 ) For this task I have done four different investigations, which is Hook's law, pH four unknown liquids, examine voltage, current change and growing yeast culture. Hook's law Hook's law given the relationship between the force applied to an unscratched spring and the amount the spring is stretched when the fore is applied. The purposes of this experiment is to see when we apply a force what will happen to the spring, therefore when we apply a force to a spring it will stretches, and if we apply double force it will stretches twice as much. I performed this experiment to determine how the extension of a spring varies with the stretching force. A spring is hung vertically from a fixed point and a force is applied in stages by hanging weights from the spring. The apparatus is set up as shown above. For the purpose of the experiment I used different gram 50 to 400 gram, and the extension of the spring I measured it metres. To start the experiment first I measured the unloaded length of the spring without touching, and then add the 50g loads, doing the same one at a time for all loads and measure the length of the stretched spring, and I recorded the results in the table. Load/ g Extension /mm 0g 0mm 50g 95mm 00g 30mm 50g 60mm 200g 90mm

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  • Level: AS and A Level
  • Subject: Science
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Thermal Decomposition of Copper Carbonate

Thermal Decomposition of Copper Carbonate ( CuCO3) Introduction: Copper Carbonate (CuCO3) decomposes by heat to form either one of two oxides, namely Copper (I) Oxide (Cu2O) and Copper (II) Oxide (CuO). This reaction can be written as two different equations: a. 2CuCO3 (s) --> Cu2O (s) + 2 CO2 (g) + 1/2 O2 (g) b. CuCO3 (s)--> CuO (s) + CO2 (g) Aim: In this experiment we will be required to identify the correct balanced stoichiometric chemical equation for the decomposition of the copper carbonate from the volume of carbon dioxide produced. Background Information: When metals are heated they react with oxygen in the air. As the metal is heated it reacts with the oxygen to form an oxide. Column II carbonates are decomposed by heat to form corresponding oxides and carbon dioxide. The temperature of decomposition depends on the reactivity (in relation to stability) of the metal. In this way, the carbonates of sodium and potassium are stable at the highest temperatures of a Bunsen burner flame whereas the carbonates of silver and copper are easily decomposed. Basic Idea: a. Copper carbonate will be heated b. Decomposition will occur c. A gas will be released and it will be collected. d. The volume of the gas that will be collected will give us an indication as to which equation is correct. Calculations - Hypothesis: (Essential Information) 'At room

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  • 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

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  • Level: AS and A Level
  • Subject: Science
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THERMOMETRIC TITRATION

CHEMISTRY COURSEWORK THERMOMETRIC TITRATION Aim The purpose of this experiment is to determine the concentrations of two acids, hydrochloric acid, HCl, and ethanoic acid, CH3CO2H, by thermometric titration; and having done that, to calculate the enthalpy change of neutralisation. Introduction You titrate both hydrochloric acid and ethanoic acid in turn with a standardized solution of sodium hydroxide and record the temperatures of the mixtures during the course of the titration. In each case a plot of temperature against time will enable you to determine the maximum temperature rise, from which you calculate both the concentration of the acid and the enthalpy change of neutralisation. Requirements * Safety spectacles * Pipette, 50.0 cm3 * Pipette filler * Expand polystyrene cup * Sodium hydroxide solution , 1 m NaOH (standardized) * Thermometer, 0-50 C0 (in 0.1 C0) * Burette , 50.0 C0 cm3 * Filter funnel , small * Hydrochloric acid , M HCl * Ethanoic acid, M CH3CO2H Safety/risk assessment: During experiment in laboratory extreme care should be taken to avoid any hazards. You should wear all the safety equipment at all times during the experiment. Eye Protection: Make sure that your eyes are fully protected. Goggles should be worn at all times during the experiment in the laboratory. Laboratory Coats: Lab coats should be worn during experiment to avoid

  • Word count: 1025
  • Level: AS and A Level
  • Subject: Science
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