Laboratory Report IB Chemistry HL IA Abstract

LaboratoryReport: IBChemistry HL IA

Abstract

Thefollowing experiment attempts to answer the research question thatwas posed and which states, “What makes some fabrics to give outdye when washed in high temperatures and why don’t some lose theircolor even in high temperatures?” This question is answered usingthe concept behind the effect of sodium carbonate in the dyeingprocess. The main function of soda ash is determined and it is notedthat its main purpose is to raise the pH levels up to the optimumpoint that allows for the best binding between the dye molecules andthe molecules of the fabric. The method used in the experiment todetermine this was through the use of several cotton fabrics. Thesefabrics were dyed using dying solutions that had the sodium carbonatefixer in the mixture. These fabrics were dyed at different pH levels.The fabrics were then left for about three hours to give time for thedye to set in after which the fabrics were then washed with dilutewater. The collected water was then used as sample sources wherebycolorimetric measurement of the absorbance of the water samples wasdone. These readings were compared against the pH levels. Thereadings with the lowest absorbance showed the optimum pH for thedyeing process to take place. The least absorbance levels show thatthe fabrics that were dyed at this pH completely bound themselves tothe dye components. The use of this study is important in tacklingthe cases of water pollution. This pollution comes about when some ofthe dye chemicals soak through the fabric and into the water. Thesechemicals can be harmful to the aquatic life. The understanding ofthe best pH to dye fabrics and other clothing materials will help inensuring that as least chemical waste gets into the water bodies aspossible (Taylor &amp Mears, 64). This idea will help in sustainingour environment for posterity. The entire dyeing process determinesthe rate at which clothes also fade. Use of the proper pH level willguarantee that cloths can undergo numerous washing cycles withoutthem fading. This experiment will show the optimum pH level thatworks best with soda ash as a fixer in dyeing.

Objective

Todetermine how the pH of soda ash used in making dyes affects levelsof dye that soak out from the dyed clothes when they are washed.

Sodaash also known as sodium carbonate is a basic compound used toprepare dyes that alter a fabric’s color. Sodium carbonate’sessential role in the dye is to raise the pH in the dye compound. Itchanges the pH of the fabric-reactive dye together with that of thecellulose fiber. This action allows the dye to react with the fiberto form a somewhat permanent connection. The main signifier of thisreaction is the color change that occurs on the fabric. This reactionhappens due to the soda ash’s ability to activate the molecules ofthe fabric. Once they are activated, they chemically attack themolecules of the dye. This reaction works for most fibers includingsilk as well. However, animal fabrics such as wool cannot have suchan effect on the dye. Since the main reason for the use of soda ashis to raise the pH, theoretically, any other compound that can raisethe pH can be used as an alternative to sodium carbonate. An exampleis sodium hydroxide. However, such a compound, especially in pureform, can be extremely dangerous. In addition, a precise amount thatis hard to measure is required in order to attain the correct pH ofabout 10.5 to 11. If less amount of sodium hydroxide is used, the pHwill be too low, and therefore, the dye will not stick to the fabric.On the other hand, if too much of the sodium hydroxide is used, thepH will get too higher and might cause the fabric to be damaged oreven cause harm to the person conducting the dyeing process. Sodiumcarbonate is, therefore, the safer option. Another advantage of it isthat even in small amounts, it can significantly alter the pH of anysolution (Reda et al., 71).

Theexperiment will attempt to show the importance of pH in the action ofdyes on fabrics. The experiment will have five different trials thatare all conducted at the same temperature but different pH levels.The dyeing process begins at a pH of 8.4 and goes all the way to11.8. Five pieces of fabric are dyed at every pH number. Thetemperature levels remain constant throughout the different trials. Acontrol experiment is done on five other fabrics that are immersed ina solution that does not contain the soda ash. After all thesefabrics are dyed at different hydrogen ion concentrations, they arethen soaked in dilute water. The water that is soaked with the dyesis then measured to get its colorimetric absorbance. The greater theabsorbance, the more the dye that has soaked into the water. Theaverage absorbance for the different pH levels will reveal the pHthat firmly allows the binding of the dye to the fabric using theBeer-Lambert’s law, the absorbance of the main component in the dyedirectly relates to the concentration of the compound. The higher theabsorbance value, the higher the amount of the dye components in thewater. From pH of about 10.6, the absorbance values begin to dropsignificantly. This observation shows that from this pH, the amountof the dye that gets soaked into the water begins to be less. Thehigh pH, therefore, helps in building a stronger covalent bondbetween the dye chemicals and the molecules of the fabric. They aretherefore much harder to separate thus making them fewer inconcentration within the solution.

Theimportance of his experiment is an attempt at reducing waterpollution. Many of these dye agents find their way into rivers andother water bodies after they soak out of the clothes and otherfabrics. These chemicals can cause great harm to the plants andanimals within these waters and around them. By determining the bestpH that is used for dyeing, the clothing industry will be made towork under these new regulations. With better binding of the dye tothe clothe fiber, less of the dye will soak out and make their wayinto rivers. Thus, the need for conducting this test is to play arole in environmental protection. With changing times, the importanceof saving the world from further harmful acts that humanity hasbrought upon it continues to rise.

Materials

Thematerials used in this experiment are the following: One pound ofProcion MX and New Back in color, one pound of sodium carbonatefixer, dyeing kit, five 250ml beakers, 3 wooden spoons, athermometer, a weighing balance, a stirring rod and sodium chloride.

Procedure

Thedye and the dyeing materials needed for the experiment were prepared.

Thefabric was also readied for easy application of the dye on it.

Differentconcentrations of the sodium carbonate fixer solution were prepared.

Aninitial piece of fabric was dyed using the dyeing compound that doesnot contain the sodium carbonate fixer. This piece of fabric was setaside for about two and a half hours.

Fiveother pieces of fabric were done the same in a solution that did notcontain the fixer.

Anotherpiece of fabric was dyed in a solution that contained the soda ashfixer at a pH of around 8.4. This fabric was also set aside for abouttwo and a half minutes. The same process was done for five otherpieces of fabric.

Anotherpiece of fabric was dyed in a solution that contained the soda ashfixer at a pH of around 9.5. This fabric was also set aside for abouttwo and a half minutes. The same process was done for five otherpieces of fabric.

Anotherpiece of fabric was dyed in a solution that contained the soda ashfixer at a pH of around 10.6. This fabric was also set aside forabout two and a half minutes. The same process was done for fiveother pieces of fabric.

Anotherpiece of fabric was dyed in a solution that contained the soda ashfixer at a pH of around 11.2. This fabric was also set aside forabout two and a half minutes. The same process was done for fiveother pieces of fabric.

Anotherpiece of fabric was dyed in a solution that contained the soda ashfixer at a pH of around 11.8. This fabric was also set aside forabout two and a half minutes. The same process was done for fiveother pieces of fabric.

Afterthe time was over, every piece of fabric was washed with dilutewater. The water that was collected for each wash was then used as asample.

Readingswere obtained from the colorimeter. The absorbance of each sample wasmeasured against the pH levels.

Thedifferent water samples gave different readings according to the pH.The average readings were then obtained and recorded in the tablebelow.

Results

Thetable below shows the readings that were obtained from the differentsamples at different pH concentrations.

Figure1: Table showing the data off absorbance readings for different pHlevels.

Theseresults show that at higher pH values, the absorbance of the watersamples is very low. This observation shows that fewer dye chemicalssoaked into the water at higher pH. This situation depicts that theeffects of soda ash at high pH values is stronger. The dye componentsare thus firmly bound to the fiber molecules and cannot be washedfrom the fabric.

Analysis

Thedata that was recorded was used to create a graph that showed how theabsorbance related to the concentration of the pH. The areas with thehighest absorbance levels display the pH where the dyes soak the mostfrom the fabrics. Thus, these pH levels are not the required levelsthat can allow the dye to bind onto the fabric. The graph below showsthese results.

Figure2: Graph showing the absorbance of water at different levels of pH.

Fromthe graph, it clearly shows that the least absorbance is obtained ataround a pH of about 11.2. This is so because, at that pH level, theabsorbance is the least. This is because the dye that bonded to thefiber at this pH stuck better than for the other pH levels.Therefore, as the pH begins to rise from around eight, the fiberchemically attacks the dye molecules and attaches much more firmly.As the pH rises to around 11, the absorbance levels continue to dropuntil around 12 where they begin to rise again. The best pH level fordyeing fabric is therefore at around 11.2. The table below shows theabsorbance readings against the concentration of the dye in thecollected water.

Figure3: Table showing the absorbance readings against the concentration

Fromthe results shown above, the least concentration is at about the pHof 10.6. This shows that at this level, the soda ash fixer works bestwith the components of the dye. The effect of the sodium carbonate isbest achieved at this point of the pH. The dye therefore completelybinds itself to the fabric and becomes hard to be removed. Using theBeer-Lambert’s law, the absorbance of the main component in the dyedirectly relates to the concentration of the compound. The higher theabsorbance value, the higher the amount of the dye components in thewater. From pH of about 10.6, the absorbance values begin to dropsignificantly. This observation shows that from this pH, the amountof the dye that gets soaked into the water begins to be less. Thehigh pH, therefore, helps in building a stronger covalent bondbetween the dye chemicals and the molecules of the fabric. They aretherefore much harder to separate thus making them be fewer inconcentration within the solution (Taylor &amp Mears, 64).

Discussion

Theresults of the absorbance readings clearly show that the pH of asolution is a huge factor that determines the effectiveness of thesodium carbonate. From a pH of around 10.6, the ability of the sodiumcarbonate to make the molecules of the fabric attack the dyemolecules becomes much stronger. This action shows that the mainfunction of the soda ash as a fixer is only to bind the dye with thefabric. For clothes to have long-lasting dyes, they have to bebleached using the soda ash and at a very specific pH that will makethe bleach and fabric bind completely. In order to get the dyesolution to the optimum levels, the sodium carbonate is added to aspecific amount to reach this pH. Therefore, the effectiveness of thesodium carbonate is better between 10.6 to around 11.4. The controlexperiment fabrics that were dyed without the use of the sodiumcarbonate fixer showed almost maximum absorbance. These results cameabout because the absence of soda ash made the dye and the fiber toloosely attach to each other. Therefore, as soon as these fabricswere exposed to dilute water, the dye in them quickly soaked into thewater and was washed away. Using the Beer-Lambert’s law, theabsorbance of the main component in the dye directly relates to theconcentration of the compound. The higher the absorbance value, thehigher the amount of the dye components in the water. From pH ofabout 10.6, the absorbance values begin to drop significantly. Thisobservation shows that from this pH, the amount of the dye that getssoaked into the water begins to be less. The high pH therefore helpsin building a stronger covalent bond between the dye chemicals andthe molecules of the fabric. They are therefore much harder toseparate thus making them be fewer in concentration within thesolution. In order to determine the effectiveness of the binder,which is sodium carbonate, the relation between the absorbance andthe concentration is used. The lesser the absorbance values, the moreeffective the soda ash fixer is.

Conclusion

Theinitial aim of the experiment was to determine the pH that makes theleast dye soak out of the fabrics. This pH level was determined to beat around 11.2.this value is the optimum level since the absorbancereadings taken from the collected water samples showed the leastreadings. This pH level provides the perfect conditions that make thedye components perfectly react with the molecules of the fabric.Using the Beer-Lambert’s law, the absorbance of the main componentin the dye directly relates to the concentration of the compound. Thehigher the absorbance value, the higher the amount of the dyecomponents in the water. From pH of about 10.6, the absorbance valuesbegin to drop significantly. This observation shows that from thispH, the amount of the dye that gets soaked into the water begins tobe less. The high pH therefore helps in building a stronger covalentbond between the dye chemicals and the molecules of the fabric. Theyare therefore much harder to separate thus making them be fewer inconcentration within the solution. The ability of knowing this isvery useful in reducing water pollution. Over the years, many dyechemicals have made their way into rivers, lakes and oceans. Thesechemicals usually soak off from clothes that did not undergo theproper methods of the dyeing process. Most likely, a binder or fixersuch as soda ash was not included or even if it was used, the pHlevel for the experiment might have been incorrect. The knowledge ofsoda ash’s usefulness will revolutionize the fabric industry.Clothes will be dyed at optimum pH amounts while using the sodiumcarbonate for maximum combination of the two compounds. These are thefiber molecules and the dye components.

Theexperiment was successful as its objective was achieved. Soda ash wasfound to be the best compound that can be used as a fixer during thedyeing process. Sodium hydrogen carbonate or baking soda would havebeen a cheaper alternative. However, it lacks the strength ofcreating significant changes in the pH of a solution. The dyecomponents will therefore fail to be fully activated in order forthem to react chemically with the molecules of the fabric material.Sodium carbonate can either be obtained in an anhydrous or hydrousstate. The anhydrous state is far stronger as its concentration isalmost pure. This type of the chemical requires small amounts for itto be effective. The hydrous state means that soda ash contains somewater and therefore it is more dilute. Lager volumes of this type areneeded to have the same impact in the pH levels.

Evaluation

Whileconducting the experiment, there were several sources of error thatcould have led to erroneous results. These sources are the following:

1.The temperature of the hot bath kept fluctuating thus, some of thefabric were dyed to different temperatures.

2.Since the experiment required a lot of time, the period it took toget and test all the samples was about two weeks. This period couldhave led to inconsistent results.

3.The trials that were done for the higher pH values were few.

4.The ideal pH that was determined in the experiment only applies forthe cotton fabric only and no other types such as silk and nylon.

Recommendation

Thefollowing recommendations suggest what changes could be made in theexperiment in order to get better results.

1.The temperature of the solution could be controlled much better.

2.The trials should have taken place within a day for in the resultsconsistency.

3.More trials should have been done for the higher pH levels toincrease the accuracy.

4.Different types of fabric should have been used in the experiment tocreate a better understanding of the experiment.

WorkCited

J.M. Taylor and P. Mears. Journal of the Society of Dyers andColourists, 107, 64. 1991.

M.Reda, El-Shishtawy, Y. A. Youssef, S. Nahed, E. Ahmed and A. A.Mousa. Dyes and Pigments, 72. 2007