Ratio of mol between Hydrogen Peroxide and Water
Ideal Gas Formula
Calculate mol of Water produced
[using Ideal Gas formula] Rearrange:
Calculate molar mass of Water using the mass of Hydrogen Peroxide
Calculate the individual % of elements in Water
Using the periodic table values:
_________
Applying the individual % of elements in Water to the molar mass
Conclusion____________________________________________________________
In conclusion the experimental value of the molar mass of oxygen is. To achieve this result, we wrote the chemical reaction, compared the ratio of mole between and, find the mole produced by water using the formula, calculate the molar mass from the mol value, calculate the % of individual elements in water, and finding oxygen’s molar mass from the overall molar mass.
Analysis & Evaluation ___________________________________________________
-In analysis, our results show an unreasonable result. The majority of the failure is from the volume result. From Avogrado’s law we know that. As such, because the average volume (0.051 L) was low, the mol resulting from it is also low. A small mol results in a large Mr value, or in our case the Mr of Oxygen is too high.
-Another point to that is that if the experiment was assuming r.t.p, our results prove to be incorrect again. If we compared the mol, the actual mol results of andusing the ideal gas laws is different than if we calculated using normal Stoichiometry.
From Stoichiometry, the actual mol of is, and if we compared it to a ratio of 2:2, the actual mol value of is also 0.138 mol. However in our experiment using the gas law, our mol result was. Again this is due to the fact of the low amount of volume recorded.
-In addition to that point, from the section to: Calculate molar mass of Water using the mass of Hydrogen Peroxide , another flaw to the experiment was the amount of uncertainty in the result. From the section we apply the ‘law of conservation of mass’ stating that no mass is created or destroyed. Or in this experiment’s case, most of the mass decomposes into Oxygen gas and finally results in the volume of water displaced from the process.
However as shown from the low amount of volume our group collected, this can result in two conclusions.
The first conclusion is that most of the oxygen gas that eventually turns into the volume of water left is lost to the surroundings (from the test tube openings) OR the second conclusion is that our group did not wait long enough and thus lost some potential volume results.
-To evaluate, the major flaw to the experiment was the value of the data collected.
Part of the reason was because we used Vaseline as a tool to reduce the amount of energy (in the form of the Oxygen gas) to the surroundings.
Vaseline is a good measure to do so, however a better alternative is probably to increase the number of trials, to have a more close system that may significantly reduce the uncertainties, and to maybe reduce the length of rubber tube (by reducing the length of rubber tube the amount of water left is reduced).
References
IB- Foundation books.
Raymond Chang (pg: 87, 181, 182, 191.etc)
