L. Objective: The objective of this experiment is to determine the mass percent of iron in an iron compound using a spectrophotometer. From there, determine which iron compounds are In the stock room bottles based off of the experimental mass percent results. II. Introduction: The objective Is to determine the mass percent of Iron In an Iron compound using a spectrophotometer. From there, determine which Iron compounds are In the stock room bottles based off of the experimental mass percent results. The objective is going to be met by first using absorption spectroscopy.
This will be done by making 6 dilutions of a known compound of Fence(ASS)2 . Absorption spectroscopy involves placing the 6 diluted solutions into the spectrophotometer. This will measure the light absorption of the individual dilutions. The absorption values will be the y values on the Beers Law Plot. Beers Law shows that there is a relationship between absorption and concentration so the x value on the Beers Law Plot will be the concentration of the 6 diluted iron solutions. To calculate the concentration, the equation is MI FL=MOVE solving for the final military.
Then the concentrations will be plotted with the corresponding absorbency values. A point on the trend line will be chosen to model the volume of the Iron compound and water for the unknowns. Four unknown Iron solutions will be prepared from this model and each Individually run through the spectrometer to determine an absorbency value. To find the military of the compound diluted, the absorbency value of the compound will be plugged in for the y value of the equation and x will be calculated using the epsilon value. This x value calculated will be the concentration of iron in diluted.
Discussion of Results: Generating the Beer’s Law Plot of the known iron compound is necessary because when calculating the absorptive of the unknown iron compounds, the compounds must fall in the range of the Beer’s Law Plot of the known iron compound. The Beer’s Law Plot generated shows a steady increase in absorbency as military increases. This is a fairly successful Beers Law Plot because al of the points were linear enough to easily make a trend line with all of the points in close range. The generated epsilon value was 3177. 1. This is the molar absorptive coefficient related to the wavelength.
This value is a part of the Beer’s Law equation and was used to calculate the military of iron in diluted. Unknown solution A was * OH. Unknown solution B was * OH. Unknown solution C was Feces * OH. Unknown solution D was Fee(NON)3 * OH. As previously stated, the mass percent of iron was calculated for each unknown. In order to identify which compound belonged to which unknown bottle, the hermetically mass percent of iron in each compound was calculated. This was done by taking the amount, in grams, of iron in each compound and dividing it by the total molar mass of the compound and then multiplying it by 100.
This allowed for a comparison of the theoretical and experimental results of the mass percent of iron in the compounds and allowed for each unknown to be identified. In regards to precision, each unknown was fairly precise among 7 groups. For each compound there was always one out of the seven groups whose value deviated largely from the toners. For unknowns A Ana c ten standard volatile was +- 2 wanly snows Tanat ten rails did not have great precision but the value is largely due to the one or two deviating results of groups. Unknown B had very great precision, which was reflected in a standard deviation of +- 0. . This can also be noted in the trials that all the results were extremely close to one another. Unknown D had poorer precision with a standard deviation of +-3 which can largely be attributed to a large deviation of two results. This experiment could have definitely been more precise, however, if one trial was disregarded in each unknown, the precision definitely would increase and have more positive results. The poor precision could be attributed to human and experimental errors, which can occur quite frequently with this particular experiment.
One human error that definitely occurred was the incorrect measurement and delivery of liquid using the pipits. Instead of stopping at the line marked zero when delivering the liquid, the two students using the pipits delivered the liquid that was located in the part of the pipette that is not calibrated. Therefore more than one or two millimeters of the designated liquids were delivered. Many other students may have been doing this in other groups as well which could account for he varying mass percent measurements. Another human error that may have occurred was the incorrect reading of instruments.
Many people often misread pipits and berets and often do not correctly measure the meniscus, which could make a difference in the results obtained. Experimental errors may also have occurred such as instruments being calibrated incorrectly. This could cause the measurements to be different than what the individual intended to obtain without any fault of the individual. If an instrument is calibrated incorrectly, one would never know and it could Just lead to poorer results. Another experimental error that could occur is involved with the spectrophotometer.