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During the experiment the crucible used was slightly damaged however did not continue to break or cause any inconvenience to the investigation. For approximately ten minutes, no reaction was visible. The substance contained no odour. After approximately fifteen minutes the piece of magnesium commenced to burn with an overall duration of twenty minutes. When burnt, the magnesium converted to bright orange colour. During the reaction the lid of the crucible was lifted to see any changes or if the magnesium had combusted, and whilst doing this white smoke escaped the crucible which may perhaps be magnesium oxide. By the completion of the reaction, it was noticed that not all of the magnesium was combusted and left some silvery remnants.
*Missing numbers are due to incomplete number of trials by the groups and/or the results lacked in validity
From the data collected from the reaction of magnesium (mg) with oxygen was used to calculate the empirical formulae and to obtain the uncertainties. The tables are arranged in a chronological order of the process of data. With the process of data will produce the empirical formulae which will be used to compare with a theoretical value. A graph is included to assist in the comparison of the theoretical empirical formulae to the experimented empirical formulae in a visual format.
To acquire the data required to evaluate the empirical formulae, the mass and moles of Mg, O and MgO were required to be calculated first. Once that is completed, there would be enough information to then calculate the empirical formulae to then compare it to the theoretical value.
Table 2 – Sample calculation when finding the mass and mole of the magnesium, oxygen and magnesium oxide (g), percentage uncertainty and empirical formulae.
Conclusion and Justification
The hypothesis of this investigation was that the mass of magnesium after combustion could be used to calculate the empirical formula of magnesium oxide and it has been established that the hypothesis is supported. Throughout the processing of data many results were removed die to the lack of validity. Thus, the data collected provided inaccurate results. When represented in Graph 1 the result did not was not equivalent to the theoretical ratio of 1 : 1. Nevertheless, when displayed in Table 6 the average ratio was 1 : 1 matching the theoretical of 1 : 1 which supports the hypothesis.
Evaluation of Data
In Graph 1, it was noticed that there were many random errors with the experiment. Such as, the constant opening of the lid when checking for the combustion during the investigation would have caused temperature changes thus, slower the combustion of the Mg. As displayed at the bottom of each table, many of the collected data were disposed as they were not valid. With many of the data remove the number of trials decreased along with the reliability.
The precision of the data can be shown by the R2 on Graph 1. The R2 value represents the decent fit to which the range from 0.1 to 1. In this investigation, the R2 value is 0.0351 which indicates that the data was not accurate which in turn reveals that there was perhaps lack of precision. Which again adds the inaccuracy of the data that does not agree with the theoretical value of 1 : 1 to be imprecise.
Overall, this investigation has provided data that is neither precise nor reliable due to the trials completed by group of researchers. Also, the empirical formula may have been affected by the rounding of three decimal places. However, the rounding of the decimal places may not significantly affect the reliability of the experiment.
Suggestion for Improvements
At the beginning of the experiment, the Bunsen burner was not under the crucible and
We had to move the Bunsen burner directly under the crucible. Because of this it may have affected how much heat interacts with the magnesium. In a replication of this investigation it is advised that the Bunsen burner is to be placed directly under the crucible. This should also be written in the method.
A Major error in the experiment was that many of the trials within the raw data were removed do to the lack of validity. These were generally due to the miss interpretation of mass or the mass had not been recorded. Because these errors came from having too many researchers doing each trial, perhaps having a smaller group of researcher will able to generate reliable results by reducing the random errors.
The method required the lid to be lifted up quickly .However, due to infor a while the lifted was lifted up and not placed down until after a few moments and the heat or magnesium oxide could have escaped from therefore affecting the results. And so, if this repeated the lifting of the lid should be constantly and quickly. Or, utilise a transparent crucible that allows the observation of the Mg but still containing the MgO.
The window was open during the experiment which caused the loss of MgO due to the strength of the wind. To minimise the loss of MgO it would be recommended for the experiment to be conducted within a fume cupboard so that no wind could increase the loss of MgO when opening the lid or as stated before a transparent crucible would allow the observation of the Mg without the need to open the lid of the crucible.