Density of Liquids
The purpose of our very first lab was to identify the density of tap water and how density can be used to recognize unknown substances. My group and I hypothesized that the unrecognized density would be 0.79g. Going into this experiment we had no clue as to which equations to use. As we read carefully through the packet, we learned to use density = mass/volume to conclude the results of the different densities. During experiments potential error may occur. While doing this project, our pipets could’ve had an extra air bubble and the scale could’ve been thrown off. All of these examples can result in a less accurate answer. Having the knowledge to find the density of liquids is very important if you are involved in the biology, medical, or chemistry field to measure liquids.
Methods and materials:
Refer to Density of Liquids: Lab 2 pg 12- Using the right
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We found that the average density of a full micropipet is 1.03(g/mL). The second table was all about recognizing the density of the unknown. The average density of the unknown is 0.79(g/mL). Table 3 shows the different densities of seven different liquids. Through this table, we discovered that the unknown liquid is ethanol. The density of ethanol is 0.789 which is almost identical to Data Table 2. There could be more options not listed in the table that have a closer density to the unknown. I feel that our results do not match our hypothesis. We found that the average density of water is 1.03(g/mL) and the average density of the unknown is 0.79(g/mL). That is a 0.24(g/mL) difference. The large difference could’ve been caused by air bubbles in the pipets, or not enough trials. (pg. 15 Table 3) The calculated percent error for the density of water is 3.26% and the density of the unknown is 3.67%, so we still have some area to improve our
the replicate shows the same trend as the first experiment. I used a measuring cylinder and a beaker to measure out the amounts of water; however these did not seem to affect the quality of my results. To increase the accuracy of my results I could have perhaps used a burette. Even though I did the best I could to keep the experiment accurate, I did. some places there were mistakes that unintentionally occurred.
We noticed changes in the weights of our equipment which caused our measurements to be incorrect. For instance, our filter paper went from a weight of 1.08 Grams to a weight of 1.11 Grams. This means that when we filtered our mixture, salt and/or sand was trapped in the filter paper which skewed our data by .03 grams. Also, the weight of our Dixie cup changed because as we were stirring the mixture we noticed flakes coming off the Dixie cup. Those flakes ended
Also we might have been shaking the test tubes at different speed which may have caused a greater number of bubbles to be released. Overall I felt that the experiment was accurate and reliable and there was not much that could have been changed on it.
I believe that a suitable procedure was followed that ensured that all inaccuracies in readings occurred due to human errors in reading. A syringe rather than measuring cylinders being used avoided errors in the measurements of volumes of solutions. This left no room for inaccuracies in not accounting for the meniscus as a syringe will leave no room for a meniscus and bears detailed volume readings, (to the nearest tenth of a cm3). This procedure yielded fewer inaccuracies meaning that results were more reliable.
The molar volume of the H2 in our experiment is very close to the theoretical molar volume, but I think that the deviation lies in the temperature of the H2O: in the first trial it is too high and in the second one too low.
In this experiment, there were several objectives. First, this lab was designed to determine the difference, if any, between the densities of Coke and Diet Coke. It was designed to evaluate the accuracy and precision of several lab equipment measurements. This lab was also designed to be an introduction to the LabQuest Data and the Logger Pro data analysis database. Random, systematic, and gross errors are errors made during experiments that can have significant effects to the results. Random errors do not really have a specific cause, but still causes a few of the measurements to either be a little high or a little low. Systematic errors occur when there are limitations or mistakes on lab equipment or lab procedures. These kinds of errors cause measurements to be either be always high or always low. The last kind of error is gross errors. Gross errors occur when machines or equipment fail completely. However, gross errors usually occur due to a personal mistake. For this experiment, the number of significant figures is very important and depends on the equipment being used. When using the volumetric pipette and burette, the measurements are rounded to the hundredth place while in a graduated cylinder, it is rounded to the tenth place.
A random error is caused by any factor which randomly affects the amount of scatter in the data. An increase in sample size allows averages to be calculated which reduces the effects of these random errors. By removing outliers in the data, the effect of random errors can be further minimised. A large amount of scatter in results indicated low precision and a large number of random errors. Some possible random errors in this experiment may have arisen when measuring the 12mL of milk solution for each test tube; some may have had slightly more and others slightly less than 12mL. Another random error could have occurred when adding 4 drops of methylene blue, some drops may have contained more liquid than others, meaning some test tubes may have contained less methylene blue indicator than
Possible errors include leaving in the test strips for too long, draining too much water into the aquatic chamber (overfilling/watering), and inverting the tubes for a shorter amount of time than required. Although there are many possible human errors that could be committed in this lab, it is important to note that the tools used for water testing could be expired and could therefore not work as well at detecting the proper levels for dissolved oxygen, pH, and nitrate.
...ore reliable if it were possible to do more trials to make sure that the data that was found was correct. This experiment could’ve been more reliable if some mistakes weren’t made like, the inaccuracy of weighing and measuring the potatoes. This could have affected the results by throwing off all the data and giving numbers that were nowhere near accurate. Another mistake that could’ve been made was the amount of solution put into each test tube. Some of the test tubes may have had to little or not enough of its solution. Some ways to fix both of these problems would be to weigh and measure each potato core more than once which is not what was done. A way to fix the inaccuracy of the amount of salt water put into each test tube would be to measure the solutions into a different container to make sure it’s an accurate measurement, then pouring it into the test tube.
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
In industry, the performance specifications for a particular pump may be known, but the tests are usually based on water as the pumping medium. For liquids of significantly higher viscosity than water, these performance curves may only be accurate at certain flow rates, or they might not be valid at all, and it might be necessary to recalibrate the specifications for higher viscosity liquids.
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
Part A of the experiment, we were measuring the density of water. In this part, we measured by difference by measuring the mass of the empty graduated cylinder which was 46.35 grams and then added 25.0 milliliters of water to it. When subtracting by difference, our mass of the water was 25.85 grams. This was close to the measurements of the water added to the graduated cylinder. The density of the water was 1.0 grams/milliliters.
The experiment was quite reliable as I found out accurately the mass gained/lost through osmosis. However, due to the time constraints I couldn?t set up measures to ensure the temperature of each potato strip was the same and the surface area. Also I would have worn latex gloves to ensure that impurities would not go into the test tube while putting the potato strips in.