Chemistry is a science that makes measurements and use data to draw conclusions. Although chemistry is about measurements all data can have a margin of error if one does not correctly follow procedure of the lab. Error may also occur even if everything is done correctly. In this experiment, you will be finding the error within certain calculations using raw data, and the determination error which will allow you to find the density of different substances. To calculate error in the experiment we will be using two terms precision and accuracy. Precision is a measure of how well an instrument or technique or student generates reproducible results. This means that if an experiment is tested multiple times the precision is how close each measurement …show more content…
Students decided amongst each other which student would be handling each measuring device. They either obtained a 50ml beaker, a 25ml graduated cylinder, a 10ml graduated cylinder, and a 10ml graduated pipet. Once the devices were decided each student weighed their individual 50ml beakers. Then students transferred 10ml of water from their 250ml beaker to their 50ml beaker using their specific measuring device and recorded the mass. Students repeated adding 10ml to their 50 ml beaker until it read 40ml and recorded the mass at 10ml, 20ml, 30ml, and 40ml. Students then shared their data on what masses they got from their individual devices. After students found the mean densities of each device they use that to calculate percent error and standard deviation from the literature value density of water. For the inquiry based project students chose and unknown metal from the back room and used an analytical scale to find the mass and record. Then they filled a 25ml graduated cylinder with 10ml of water and added the unknown metal. By using the water displacement students were able to find the volume and calculate the density of the metal. Students then compared their density with literature density values and chose which value was closest to …show more content…
This device also contained the largest amount of standard deviation which I believe is because it is the largest measuring device and is inefficient when transporting 10 ml increments. The most accurate devices were the 25 ml cylinder and the 10 ml pipet because they are smaller devices that have more precise measurements increments that allow the user to better weigh out 10 ml increments. The biggest margin in error most likely occurred when measuring out 10 ml with each device. The 50 ml beaker does not contain precise measurements and it contains a larger volume which causes measuring 10 ml harder. Whereas the 10 ml cylinder and pipet had more precise measuring allowing the user to better measuring out the precise 10 ml and get and accurate density of
The purpose of this experiment is to determine the absolute configuration of an unknown chiral secondary alcohol using the competing enantioselective conversion (CEC) method. This method uses both R- and S- enantiomers of a chiral acyl-transfer catalyst called homobenzotetramisole (HBTM), in separate parallel reactions, and thin layer chromatography to identify the stereochemistry of the secondary alcohol, whether it be an R- or S- enantiomer. Quantitative analysis was performed using a program called ImageJ after the appropriate picture was taken of the stained TLC plate. The molecular structure of the unknown alcohol was identified using 1H NMR spectroscopy by matching the hydrogens to the corresponding peak.
Start with the hot water and first measure the temperature. Record it. 8. Then pour 40 ml into the beaker. You can measure how much water was used by looking at the meniscus.
In addition, the data points were quite far apart. Having more intermediate data points would have enabled the scientists to more accurately model the continuous nature of the data with a discontinuous series of points. Finally, stopping the flask more quickly would have allowed less gas to escape. Using a mechanical solution that could stop nearly instantly would have been ideal.
Theory of Water of Displacement: A volume of water was measured. A second volume of water was measured when the metal cylinder was added. The initial volume was subtracted from the second (total) volume to get the volume of the metal cylinder.
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
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.
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
Measure the weight of a small stone to fit inside the opening of a 50ml graduated cylinder.
After the groups were separated into groups of three or four, we were instructed to perform three trials. In each group each person got to be an experimenter and a subject at least once. First we placed ten pennies into each cup, and let the blindfolded subject feel the cups at equal weight. We then placed a penny into the experiment cup (A) and told the subject to guess which was the heavier cup. If the subject guessed correctly, we would continue to give them the same two cups, in different hands and order, until they had guessed correctly five times. If the subject guessed incorrectly, another penny was added until they could guess right five times in a row. The purpose of the first weight was to get the subject and experimenter accustomed to the nature of the experiment. After the first trial of ten starting pennies, fifteen pennies were used as a starter. After that sixty pennies were used.
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.
Planning Firstly here is a list of equipment I used. Boiling tubes Weighing scales Knife Paper towels 100% solution 0% solution (distilled water) measuring beakers potato chips Cork borer. We planned to start our experiment by doing some preliminary work. We planned to set up our experiment in the following way.
a. In this lab the main objective was finding the percentage of water in different type of
Introduction: This lab was the first one of the semester. We started off with the height/weight ratio lab. It was here that the expected result for everyone around the table was 4 centimeters divided by kilograms. Therefore, if the expected result based off a different group of people was 4 cm/kg, then the same formula should be true for the people around the table.
Milk was poured from the graduated cylinder into a cup with a cheesecloth on it 12. The milk and curds drained for 5 minutes 13. A weighboat was placed on a scale, the scale was then zeroed 14. The mass of the cheesecloth and curds were recorded 15. The mass of the cheesecloth was subtracted to find the mass of the curds 16.
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.