Investigating the effect of different liquid densities on the time taken to release 25 ml of alcohols Essay

* Research question* Does the channelise in gas densities at the alike temperature affect the beat put one overn to anaesthetise 25 ml of the alcoholic drink from a 50 ml buret?* Variables* Independent variable The liquid dumbness / g ml-1.* Dependent variable The time abridgen to spillway 25 ml of the alcohol from a buret / s.* Controlled variables* The volume of alcohol in a burette / ml.* The temperature of the alcohols / oC.* The absence of unnecessary substances or ions.* The same burette for the entire try out.* Prediction* The time requiren to stretch forth 25 ml of the alcohol from a 50 ml burette is, stated by F. Weinberg (1984) 1, dependent on flow velocity and in special(prenominal) argon precise sensitive to sm on the whole changes in the density difference between the two liquids.* My anticipation is, the higher the liquid density is, the more time taken for 25 ml of the alcohol to be released from the burette. The time taken to release 25 ml of alcohol increases in order wood spirit, neutral spirits, Propan-1-ol, Butan-1-ol and Octan-1-ol.* Method* tool* 50 ml burette (Uncertainty 0.500 ml).* Retort stand.* 125 ml ethanol C2H5OH 95.0%.* 125 ml wood spirit CH3OH 99.5%.* 125 ml propan-1-ol CH3(CH2)2OH 98%.* 125 ml butan-1-ol CH3(CH2)3OH 99%.* 125 ml octan-1-ol CH3(CH2)7OH 94%.* Thermometer (Uncertainty 0.0500 oC).* 5 x funnels.* 50 ml conical flask.* Casio stop watch (Uncertainty 0.0100 seconds).* Distilled piddle.* Risk assessment* The procedure uses virulent alcohols. nonably, suggested by Department of Chemistry Imperial College London (2006) 2, less than 2 teaspoons (2 ml) of methanol arouse trend blindness, and 2 table spoons (30 ml) can cause death. This toxicity is mainly due to it being converted in the body to takeic acid and formaldehyde, which first attack the cells in the retina, then the other vital organs. Plus, propan-1-ol is use as a common solvent and cleaning agent in chemistry laboratories. Also, be cause it evaporates rapidly, IPA is widely utilise in astringents to cool the skin and constrict surface blood vessels.* Goggles and lab coat are therefore needed to be worn passim the experiment.* Procedures1. Close the strike hard and run some distilled water into the top of the burette, then swish the burette up and down to let the water clean all the inside of the burette. Open the tap, let the water drain out.2. Attach the burette to the retort stand and take care that the burette is upright and stable.3. Close the tap and use the funnel to put 25 ml of ethanol into the burette.4. Remove the funnel, make sealed that there is no air bubble inside the burette. posting the temperature of ethanol by the thermometer.5. Put the conical flask under the burette, adjust the height of the burette so that the tip of the burette is just above the lip of the conical flask.6. Open the tap and immediately cabbage the stop watch.7. Stop the watch when 25 ml of ethanol is fully released f rom the burette.8. Continue to open the tap and collect the remained ethanol in the burette.9. Repeat step 1 to 8 four more times.10. then(prenominal) change ethanol with methanol, propan-1-ol, butan-1-ol and octan-1-ol. Experiment step 1 9 with to all(prenominal) one alcohol.* Range and repetitions of experiment* in that location are 5 contrary ranges (The lowest esteem 0.789 g ml-1 & the highest value 0.826 g ml-1, Please denote to Data sight and Processing - Processed data).* The initial procedure is repeated 5 times and so 25 results are recorded.* Control of variables* The volume of each alcohol sample remains constant for either political campaign at 25 ml. Different volumes of the alcohol sample whitethorn cause inaccuracies in hurt of measuring the time taken to release. For instance, larger volume of the same alcohol sample certainly takes lifelong time to be released.* The temperature of each alcohol sample need to remain constant for every test at 20 oC (29 3 K). The analysis, written by Weirauch, D. A., Jr. (1998, December) 3, of the high-temperature spreading dynamics for liquids affecting density shows that they can be modified with a constant shift factor. Therefore, higher temperature of the same alcohol sample may reduce the time taken for the alcohol to be released.* The burettes and funnels are rinsed carefully with distilled water prior to the experiment to insure that inside the burettes do not contain any unnecessary substances/ions. If present, they may react with the alcohols to form products which have different liquid density, as opposed to original liquid densities of the alcohols at 20 oC (293 K).* The same burette is used for every measurement. This is because burettes from the same manufacturer cannot be guaranteed to have the same radius of the tips (possessing relatively small values). The use of different burettes can result differences in the time taken for the alcohol to be released.DATA COLLECTION AND PROCES SING* Raw data tableAlcoholsDependent& independentvariablesEthanolMethanolPropan-1-olButan-1-olOctan-1-olLiquid density/ g ml-1at 20 oC (293 K) 40.7890.7910.8040.8100.8261st repetitionTime taken to release 25 ml of alcohol from a burette / seconds 0.010039.043.067.082.01122nd repetitionTime taken / seconds 0.010041.044.069.081.0cxv3rd repetitionTime taken / seconds 0.010038.046.070.083.01114th repetitionTime taken / seconds 0.010039.042.071.080.01145th repetitionTime taken / seconds 0.010040.045.070.079.0110.Table 2.1 shows the collected raw data table.* Processed data* Calculating the designate time taken to release 25 ml of alcohol from a burette* Mean time taken / s = (1st + 2nd + 3rd + 4th + 5th trial data) 5.AlcoholsDependent& independentvariablesEthanolMethanolPropan-1-olButan-1-olOctan-1-olLiquid density / g ml-1 at 20 oC (293K).0.7890.7910.8040.8100.826The mean time taken to release 25 ml of alcohol from a burette / 0.0100 seconds39.444.069.481.0112Table 2.2 shows t he processed mean time takento release 25 ml of alcohol from a burette.* Presentation of processed datagraphical record 2.1 shows the birth between the liquid density and the mean time taken to release 25 ml of each alcohol from a burette.* Treatment of uncertainties* I try to read off carefully volume of the burette from the bottom of the meniscus with my eye level at the meniscus in order to make sure that the volume of each alcohol sample used is only 25 ml.CONCLUSION AND EVALUATION* Graph analysis* According to the presented graph of the mean time taken to release 25 ml of different alcohols, there is a very strong positive correlation between the liquid density and the mean time taken to release 25 ml of alcohol from a burette as a very good line of best fit can be observed. (Please occupy to Data Collection and Processing - Presentation of processed data - Image 2.1).* Conclusion* The results demonstrate that, the higher the liquid density is, the longer time taken for 25 ml of the alcohol to be released from the burette.* The conclusion totally agrees with my hypothesis.* rating of procedures* Strengths* Safety in the laboratory is highly maintained (by wearing goggles, lab coat and being careful with glass apparatus to avoid any poisonous alcohols that may splash).* Standard ranges and repetitions are met, a very strong positive correlation between the liquid density and the mean time taken to release 25 ml of alcohol from a burette is observed.* Quantitative investigation, with repeats strongly supporting each other, successfully proves that the expectations based on scientific knowledge are totally correct.* Weaknesses* Several inevitable uncertainties occur throughout the whole experiment which may account for inaccuracies in the collected data.* The concentrations of the alcohols vary from 94.0 % to 99.5 %. The differences in concentration of each alcohol affect the reliability of the data, since 25 ml of pure alcohols (or 5 alcohols with the sa me concentration) may take different time to be released from the burette.* Although there is a very strong positive correlation between the liquid density and the mean time taken to release 25 ml of alcohol from a burette, the independent variables (liquid density) do not increase constantly due to the limited number of available alcohols (Please refer to Data Collection and Processing - Presentation of processed data - Image 2.1).* The entire procedures, although are simple, take a long time to finish because of the 50 ml burette need to take at least 3 times to add 5 alcohol samples (5 repetitions for each alcohol), 25 ml each. boilersuit there are 15 times to add 25 alcohol samples since I decide to inquire 5 different alcohols. The more time I need to add more alcohols into the burette, the more likely inaccuracies to occur.* Improving the investigation* The procedures can be partially replaced by computer data logging suggested by Laurence Rogers (1995) 5 to prevent uncertain ties from human errors when stopping the watch. The experiment can be programmed to collect the data (Time taken for 25 ml of the alcohol to be released from the burette) automatically.* More alcohols with liquid densities within the ranges (The lowest value 0.789 g ml-1 & the highest value 0.826 g ml-1) can be tested to fill the 2 gaps between methanol and propan-1-ol, butan-1-ol and octan-1-ol in the presented graph. For instance, penta-1-ol has the liquid density of 0.815 g ml-1 at 20 oC (293 K) 6.* Pure alcohols should be bought in the same concentration to ensure the reliability of the collected data. Otherwise, diluting the alcohols to the same concentration can be less expensive, yet time consuming.* A larger burette, for instance, with measuring volume of 75 ml (only 2 times to add 5 alcohol samples, 25 ml each) will reduce the times need to pour more alcohols into the burette to 10. Not only this change in equipment may save time of experimenting, but also minimise the unce rtainties.Bibliography1 Weinberg, F. (1984, December). liquid flow from a low to a higher density liquid. Metallurgical and Materials Transactions B, 15(4), 681. Abstract retrieved show 8, 2009, from Springer Link. Web site http//www.springerlink.com/content/n84726w432072592/2 Department of Chemistry. (2006, August 25). Biological effects of Methanol and big Alcohols. In Ethanol. Retrieved March 8, 2009, from Imperial College London. Web sitehttp//www.ch.ic.ac.uk/rzepa/mim/environmental/html/ethanol_text.htm3 Weirauch, D. A., Jr. (1998, December). Predicting the spreading kinetics of high-temperature liquids on solid surfaces (Vol. 12). Alcoa Technical Center. Retrieved March 8, 2009. doi10.1557/JMR.1998.04784 Process Calculator. (2009). SG. In Liquid Density. Retrieved March 8, 2009, from substructure Business Models Pvt Ltd. Web site http//www.processcalculator.com/Liquid_Density.aspx5 Rogers, L. (1995, May). Sensors and The Data-Logger. In Hardware and software. Retrieved Mar ch 9, 2009, from School of Education, University of Leicester Web site http//www.le.ac.uk/se/lto/logging/test1.html6 Process Calculator. (2009). SG. In Liquid Density. Retrieved March 8, 2009, from Radix Business Models Pvt Ltd. Web site http//www.processcalculator.com/Liquid_Density.aspx