Suppose that a student doing this experiment ran into some procedural and calcul

Question

Suppose that a student doing this experiment ran into some procedural and calculation difficulties. State the effect each of the following would have on the mass percent H2O2 determined from this experiment. Briefly explain.

1) The student neglected to take into accoundt the pressure of water vapor in the system when doing the calculations.

2) The H2O2 solution had decomposed slightly agter standing for a while, so its concentrations was somewhat lower than the laboratory insuctor had reported.

3) The student failed to read the barometric pressure at the time of the experiment. When she read the pressure the next day for use in her calculations, it was .50 in. Hg higher thatn it had been during the experiment.

Explanation / Answer

1) student mistakenly added the pressure created by the water vapour as the pressure coming from oxygen. He/She might have calculated the amount of oxygen coming from H2O2(decomposition) more than actual and had resulted in determinating greater mass %age of H2O2 than actual.

2)The initial concentration might have changed (decreased) after elapse in time and student will get less amount of oxygen created than with higher concentration in given time interval. hence he will determine lower mass %age.

3) Greater pressure observed (0.5in Hg)means he has taken into acount the amount of oxygen produced after due time interval. this will result in in calculating higher amount of oxygen produced from decomposition and higher mass %age than original.

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