2. The percentage by mass of oxygen in a compound containing potassium, chlorine
ID: 481150 • Letter: 2
Question
2. The percentage by mass of oxygen in a compound containing potassium, chlorine, and oxygen (K.Ciro) was det experimentally. The technique used is as follows. The solid (KeCloo termined compound is weighed. Then it is heated in a crucible. The solid decomposes to produce oxygen gas and a salt. Because the oxygen gas is escaping, the mass of the original solid decreases. From the mass of oxygen lost and the mass of the original compound, the percentage by mass of oxygen in the original compound is determined. A student performs five trials and determines the following by mass of oxygen in the compound (KCI,0) by mass of oxygen Trial in the compound 38.933 38.940 38.871 38.892 38.900 a. Determine the average experimental percentage by mass of oxygen in the compound. 38.901 b. If the actual value of the percentage by mass of oxygen in this compound is 39.13%, determine the percentage error. 39.13 38a Do -0.5022 3a.Explanation / Answer
d. From the given reaction of decomposition of KClO3
2KClO3 --> 2KCl + 3O2
The results show occurence of systematic error. The values are close to each other.
e. the possible soruce of error may arise from inaccurately weighing the original solid strating material. Another source of error may arise from incorrect measurement of the weight of oxygen collected during the experiment.
f. the experiment describing the decomposition of KClO3 to KCl and O2 is described here. The values though close to one another have error associated with it. The error in measurement may come from losses occuring during colection of oxygen released in the experiment and thus incorrect weight measurement of the left solid after the decompoisition reaction. The experiment however shows succesful decomposition of KClO3 occuring in this case.
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