Discussion15

Discussion15 - molecules with sufficient energy to react...

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Discussion In the first part of the experiment, we timed the production of 14mL of O 2 (g) with three different solutions at a constant temperature of about 24°C. Solution 1 and 2 shared the same concentration of KI; Solution 1 and 3 shared the same concentration of H 2 O 2 . The data allowed us to calculate the appropriate rate law for the reaction by solving for the exponents, x and y. The order with respect to [KI] was measured to be 0.2, which we presumed to be one, and 0.7 with respect to [H 2 O 2 ], which we also presumed to be one. This revealed the overall reaction to be second order. Thus, the rate law we found appropriate to the reaction was: Rate = k[H 2 O 2 ][KI] 2 nd Order The second part of the experiment was conducted using the same concentrations as Solution 1 in Part 1. With concentrations the same, we increased the temperature of the reaction by 16°C, to 40°C. According to our calculations, the rate of the reaction tripled at the increased temperature. This result was expected since the energy of the molecules increases with temperature, which implies the fraction of
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Unformatted text preview: molecules with sufficient energy to react will also increase. In Part 3, we let the decomposition of hydrogen peroxide (H 2 O 2 ) go to completion, measuring the total volume of oxygen gas that could be produced by the reaction. The ideal gas law gave us the moles of oxygen, which we plugged into the reaction 2 H 2 O 2 (l) 2 H 2 O (l) + O 2 (g) and found the molarity of hydrogen peroxide to be 0.08M. Our experimental value, 0.088M, differed by 9.1%. The experiment relied on certain variables, such as pressure, temperature and concentration, being constant to assist in our calculations. We didn’t achieve constant temperature in several parts and had trouble equalizing the syringe to maintain constant pressure. The majority of the error in our calculations can be accounted for by these factors. Our methods improved and got more accurate as the lab progressed....
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This note was uploaded on 04/08/2008 for the course CHEM Chem 1A taught by Professor Van koppen during the Winter '08 term at UCSB.

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