Research question †How many molecules are there in a liquid drop? Essay

Variables In capable variable The nature of the mobile fell.Dependent variable Mass of molten drop.Constants * Concentration of the runninesss* The volume of a drop* Temperature of the liquefiablesHypotheses and visition The heavier the liquid apply i.e. a liquid with a high relative molar piling, the much than the lean of blood corpuscles per drop. I predict this as the RMM (relative molar the great unwashed) is the mea sure of the voltaic pile of molecules that make up a mole of a substance, and hence the higher the mass is, the more(prenominal) the total of molecules there obligate to be. Thus, the liquid would fuddle more frame of molecules per unit of measurement volume as compared to ane with a lower RMM, keeping in mind the selfsame(prenominal) closeness is taken.Apparatus 1. Measuring scale, in grams ( 0.01 g)2. eye dropper3. Beaker, 50 ml4. Distilled urine5. glycerin6. Ethanol7. Ethylene ethene glycol8. Tissue paperMethodology 1. We collected th e apparatus needed and thrifty the mass of the 50 ml beaker. We c eithered it m1.2. Using a dropper, we put 20 drops of irrigate in the beaker. We measured the mass of the beaker + water, and c altogethered it m2. The mass of the 20 drops of water was found by subtracting m1 from m2. The answer was dual-lane by 20 to govern out the mass of champion drop of water.3. We repeated step 2, with water, use 40, 60, 80 and 100 drops. This make the experimentation more accurate i.e. gave a more precise mass of the water drop.4. then, we repeated steps 3 and 4 with the three early(a) liquids ethyl alcohol, glycerine and ethylene glycol.5. Values were celebrated down. Further calculations were make using the mole equation Number of moles =And, a akin using Avogadros constant, where the sum of molecules in unitary mole of a substance is 6.023 10.Controlling, varying and monitoring the variables The independent variable was varied by using not whiz, but quartette different typ es of liquid. These were distilled water, glycerine, ethanol and ethylene glycol. These liquids boast different relative molecular the great unwashed. The change of the dependent variable were monitored by using a measuring scale to solemnize the change in the masses of the same be of drops when different liquids were tried. The controlled variables were unplowed constant-(a) All the quaternary liquids had the same concentration of 1 mol/dm. This was necessary as a change in the concentration produces a change in the number of moles of the liquid in the drop.(b) The drops were all of the same sizes, and hence of the same volume. the volume was kept constant by using the same dropper for all(prenominal) trial, and furthermore, by applying the same pinch (from the fingers) to the bulb of the dropper.(c) The temperature of the liquid was necessary to keep constant as tear down trivial changes in temperatures can make a liquid run or contract, ever-changing its volume. The ex periment was carried out at room temperature, for all trials. The temperature of the surroundings was unchanged throughout the experiment i.e. the temperature of the air conditi nonpareilr was not altered. collection relevant and sufficient entropy Before the experiment, several trials were executed in put in to get a gist of the experiment and recognize and remedy either defects. Examples of errors include applying different amounts of obligate on the dropper bulb, tolerant us drops of different volumes. We in minimal brain damageition noticed that almosttimes, more or little drops were added than needed, due to not observing well or counting the number of drops being put into the beaker carefully. We corrected this by paying more management to the number of drops being put into the beaker. These errors were made right and taking trials earlier the experiment ensured we had a more precise, accurate and relevant experiment.We in like manner obstinate to take the mass as the dependent variable, instead of volume, as we were provided with a measuring scale which was much more accurate ( 0.01 g) as compared to even out the most accurate measuring piston chamber (10 ml, 0.1 ml). This reduced the overall indecision of the equipment used and hence the general error of the experiment, and made the data more relevant and certain. On the other hand, it was made sure sufficient data was collected as we took five different trials (20, 40, 60, 80 and 100 drops) for apiece of the four liquids, just to medium it down and get the mass of ace drop (for each liquid). Furthermore, we measured the masses of high numbers of drops ex- 60, 80, 100 drops etc. as the higher the number of drops, the lesser the error uncertainty.The model deviations of the averages of each set of drops has not been compute, as it isnt the concluding value needed (i.e. the average mass of one drop is the final value needed). I have rounded off those averages to three ten-fold places (instead of one) as the values are very small. The average mass of one drop has been rounded off to the same number of places as the standard deviation, that is two significant figures.The calculations are shown on the pastime page.Calculations * The averages have been calculate the following way-For casing, taking the values for water === = 0.0634 = 6.3 10 (to one dp)* The standard deviation for the averages have been found out in the following way-1. First the average of the values have been found. Taking the manikin of the values of water the average is 6.3 10 g (0.0634 g).2. Then, the battle mingled with each reading and the average was found. That is0.058 0.0634 = -0.00540.059 0.0634 = -0.00440.065 0.0634 = 0.00160.067 0.0634 = 0.00360.068 0.0634 = 0.00463. Next, these differences were squared (in order to remove any negative signs)(-0.0054) = 2.916 105(-0.0044) = 1.936 105(0.0016) = 2.56 106(0.0036) = 1.296 105(0.0046) = 2.116 1054. These squares were then added, and the sum was divided by (n 1), where n is the number of values.= 2.13 1055. Finally, the square melodic theme of this number gives the standard deviation of the average= 4.615 10However, this value is evermore rounded off to one significant figure (hence, so is the average value) giving 0.2 s.6. This method was used to get the standard deviation of the occupy of the four averages as well.* The number of moles of the liquid contained in the drop was calculated by the shape = Number of moles = .The relative molar masses of the four liquids were taken from literature values Water 18 Glycerine 92 Ethanol 46 and Ethylene Glycol 62. (www.wikipedia.com)* The number of molecules present in the drop was found out by using Avogadros formula which states Number of molecules = Number of moles of the substance (6.023 10)Data processing chart 1 This graph shows us two things the mass of the liquid drop as well as the number of molecules each drop contains of four different liquids, which are placed on the X axis. Comparing this graph, and literature values, we can see there is an indirect relationship between the mass of the drop and the number of molecules. This relationship is most importantly affected by the relative molar mass (RMM) of the liquid. A higher RMM means a lesser number of moles in a given volume, as is seen in the study of glycerine, where the number of molecules is seen to be relatively lesser when compared to its mass and other values. This means that glycerines molecules are heavy, large or more dense. Whereas in the case of water, the number of molecules is seen to be much higher as compared its mass which suggests that water has a lower RMM, relatively, and hence is brightness, or smaller, on the whole.This graph also shows us anomalous results regarding the mass of the ethylene glycol drop. Technically, the ethylene glycol drop should have a great mass as when compared to ethanol, as it has a greater RMM (valu e got from literature data) and a lesser number of molecules. This could have been due to errors in the volume of the liquid drop (for example), which have been explained in the evaluation.Conclusion Thus, we can conclude by stating that the hypothesis has been proved wrong i.e. as the relative molecular mass of a liquid increases, or the mass of the liquid drop increases, the number of molecules it contains decreases. This is because the relative molar mass is a measure of the mass of one mole of a substance (relative to 1/12 of the mass of hundred 12), and one mole of any substance consists of the same number of molecules 6.023 10. However, one mole of a substance may differ in mass from one mole of another substance.This is solely because of the mass of the particles contained in that one mole of the substance. A compound which has i) many atoms ii) heavy atoms (in one molecule), will have a higher relative molar mass than a molecule of a compound which has lesser atoms or lig hter ones (or both). In this experiment, we are not measuring the number of molecules in one mole of these for substances, but in one drop. hence, the volume remains constant here.Thus, the only way a drop of a substance (of the same volume as the other three drops) will have more number of molecules than any other will be by the liquid having a lower RMM, so that more number of particles would fit in that drop. Taking the example of water, its mass is relatively lower as compared to the number of molecules it contains. This simply suggests that a water molecule will either have lesser atoms, or lighter atoms, or both. On the other hand, the molecule of glycerine is fairly heavy, with an RMM of 92 (whereas the RMM of water is 18) and we can see by the graph that the number of molecules it has is relatively lower than that of waters up to now the mass of the drop is higher than that of waters. This shows that glycerine molecules are heavier than water molecules. Thus, as the mass of the drop increases, the number of molecules it contains decreases.Errors and observations Glycerine doesnt disperse in water, hence it was difficult to clean the dropper and the measuring cylinder containing it. Ethanol, being an alcohol, was volatile. Thus, it easily evaporated. This could have been the reason why the mass of the ethanol drop was lower than expected. Any slight changes in the room temperature would have caused an error to the volume of the drop, since it is so small in volume, ex- arising of the laboratory door, changing of the temperature of the air conditioner, opening of the windows. However, it was made sure as far as it could to avoid these changes. The same dropper was used for each liquid, in order to try to maintain the volume of the drops. This could have resulted in the liquids mixing up, hence altering the mass values. Minute air particles like dust and dirt could have affected the experiment by changing the mass of the drops. The readings taken towa rds the end of the laboratory session were slightly heavier (due to some liquid still remaining in the instrument). The angle with which the dropper was held made a difference to the size of the drop i.e. if the drop was held vertically, the drops flowed faster and were heavier. Whereas if the dropper was held more horizontally, the speed of the flow of the drops was slower and the size was smaller. After cream the dropper, the first drops were slightly heavier as compared to the last ones due to the extra pressure being applied to them from the liquid above. Air bubbles were trapped in the liquids. Glycerine had the largest and most viscous drops whereas water had the smallest and least viscous drops. Sometimes, drops were added to a measuring cylinder which already contained drops, intentionally. For example, if a measuring cylinder had 20 drops of water, 20 more drops were added and then the mass for 40 drops of water was measured. In case there were any errors for the first 20 drops, they could have carried on for the abutting 20 drops. The liquids could have been slightly impure, as they were all being used for the same experiment (some could have mixed). This would have made a difference to the mass.Evaluation 1. In order to clean the glycerine left from the sides of the dropper etc, a substance which dissolves glycerine could have been used, for example alcohol.2. Since ethanol was volatile, the experiment could have been carried out in an area where there was no unbowed wind. The ethanol bottle could have been kept shut for most of the time, and the masses could have been taken down quickly.3. The room temperature could have been well monitored by maintaining a constant temperature (of the air conditioner) and strictly ensuring that the windows or the door werent opened.4. Extra care and hygiene could be taken to ensure that the liquids didnt mix up. This could be done by making sure that attention is paid to the lab while performing it and the volu nteers arent distracted. To make sure the dropper was well cleaned for each trial, liquids which dissolved the liquids being used could have been applied. Another way could be to find another dropper with the exactly same diameter as the one being used. This would decrease the errors by a great deal.5. To ensure dust particles didnt fall into the liquids, a conical flask could be used.6. After each trial, it should be made sure that the beaker is cleaned well and wiped well too, by tissue paper. In order to ensure that there is no extra liquid remaining, the mass of the beaker could be checked before adding the drops.7. One set angle (of the dropper) should be used, for example the dropper could held at approximately 45 to the laboratory surface gameboard for all trials. The pressure applied to the bulb should also be monitored.8. When the dropper is full, the experiment could be carried out more slowly and the number of drops be carefully monitored. This would make sure that the size of the drops was not too large, and that the number of drops being added to the beaker were carefully monitored.9. To decrease the number of air bubbles, the bottles which contained the four liquids could be shut for most of the time and not moved around much. It should also be made sure that the dropper was full with sufficient liquid so that there would be very less air bubbles, or none at all.10. To avoid carry-on errors, each trial could be performed by and by cleaning the beaker with water and wiping it well with tissue, each time.These would be the improvements I would add to my experiment in case I perform it again. I would also like to use more, different liquids, in order to get a broader idea of the experiment.