Use reference materials and the web to construct a cookbook explaining how to do
ID: 995800 • Letter: U
Question
Use reference materials and the web to construct a cookbook explaining how to do the following types of chemical reactions. You must include specific step by step instructions so that someone else could conduct the experiment. You will be asked to choose one experiment to conduct in class. Please clear your choice with me, as some to these may be proscribed. Neutralization reaction Oxidation reaction Clock reaction Precipitate reaction Saponification reaction Polymerization reaction In addition, you need to include instructions on how to perform the following separations. Distillation CrystallizationExplanation / Answer
Type of reactions,
1. Neutralization reaction : Is a simple type of acid-base type of reaction. For example reaction of HCl with NaOH,
HCl + NaOH ---> NaCl + H2O
HCl (aq) taken in an erlenmeyer flask and is titrated with a known concentration of NaOH (aq) taken in a buret. The reaction is done in presence of indicator as phenolphthalein.
2. Oxidation reaction : Is a typical reaction where a species is oxidized with an oxidizing agent
Fe2+ + ClO- <==> Fe3+ + Cl-
Fe2+ is getting oxidized to Fe3+ by ClO- oxidizing agent.
Fe2+ species taken in erlenmeyer flask and is titrated with standard ClO- solution.
3. Clock reaction : Is reaction of I2 with another reagent as thiosulfate. For example H2O2 is mixed with KI, starch and Na2S2O3. H2O2 oxidized KI to form I2 which reacts with Na2S2O3. Once all of Na2S2O3 is used up, excess I2 present reacts with starch to form a deep blue-violet color complex and this is the end point of reaction. This reaction is known as iodine-clock reaction.
4. Precipitation reaction : Here a reaction progress is measured as a function of amount of precipitate generated. Say a reaction of Ba(NO3)2 with Na2SO4,
Ba(NO3)2 + Na2SO4 ----> BaSO4 (ppt) + 2NaNO3
BaSO4 is formed as precipitate in the erlenmeyer flask when Na2SO4 is added to it.
5. Saponification reaction : Is hydrolysis of fatty acid to corresponding carboxylic acid by base. For example,
CH3CH2COOCH3 + NaOH ----> CH3COONa + H2O
The ester reacts with base to form saponified product a salt as shown above. The ester is take in erlenmeyer flask as a solution and statdarized NaOH is added by buret. The reaction can be monitored by an indicator which shows a color change when all of ester is hydrolysed and excess base is present in solution.
6. Polymerisation reaction : Is formation of long chain high molecular weight material starting with smaller unit known as monomer. For example, polymerisation of ethylene to polyethylene,
nCH2=CH2 -----> -(-CH2-CH2-)n- (polymer)
The reaction is done in presence of a titanium catalyst.
Separation techniques
1. Distillation : Is performed in a dsitillation unit with mixture of liquid to be separated taken in a flask to which distillation condenser is connected. The separation may be performed at atmospheric pressure (for low boiling liquids) or at reduced pressure (for high boiling liquids). The mixture is heated slowly to separate each component separately and collected in different flasks.
2. Recrystallization : Is a technique of separation or purification of solids from other solid components or impurities. The solid is dissolved in a solvent in which it is least soluble at room temperature and completely soluble at elevated temperature. Solution is filtered under hot condition and allowed to stand. Crystals of pure solid separats out of solution which is then filterted out and isolated. Impurities remain in solution as soluble.
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