We have to stir the water in beaker to get the perfect temperature. * The rubber band which is used to tight the flask may release more vapour because the rubber band is not properly tight. The Dumas method is the method used to calculate the molecular weight of the substance. * This method has a condition that the substance used must be a liquid.
The liquid that has boiling point above room temperature and below the boiling point of water. * After completing the experiment, we came to know that temperature and pressure effect the final result. The flask is completely filled with vapour only when it is removed from the hot water bath. However, when the flask cools some of the vapour condenses in the flask. As a result of this the final reading of the weight increases and affects the result. * The given sample (2–propanol) has molecular weight 60. 08 gm/mole and our result shows 56. 43 gm/mole. So the percentage error is 6. 078%. * This is due to the effect of temperature. If we might had increase the temperature, them the result would be much closer than actual molecular weight of the 2-propanol. The measuring cylinder that has been used to measure the volume that might have some drop in the measuring cylinder. This result in increase in the volume and affect the final result.
* The unknown sample given has molecular weight been found to be 76. 6026 gm/mole * The range of the molecular weight of the unknown sample was found to be 76. 53 gm/mole to 82. 68 gm/mole
The Essay on Chemistry uncertainty conical flask
The conical flask was weighted with the balance and the value was recorded. 2) The beaker was filled with distilled water and the water was added into the conical flask up to the 60 mL mark. The dropper was used when water level was approaching the 60 mL mark. 3) The weight of the conical flask containing water was recorded. 4) The mass of water was found by subtracting the weight of conical flask ...
CONCLUSION: *
The molecular weight of give sample (2-propanol) was found to be 56. 4286 gm/mole * The actual molecular weight of give sample (2-propanol) is 60. 08 gm/mole * The percentage error of give sample (2-propanol) was found to be 6. 78%. * The molecular weight of unknown sample was found to be 76. 6026 gm/mole Answer: – The flask is immersing in the boiling water bath but the temperature at upper part of the flask is lower than the bottom part. So, when the vapour is form in the beaker than it gets condensed in the same beaker. These errors develop variation in the weight of the flask. To minimise this error subtract and add the percentage error of the known sample to the molecular weight of the unknown sample. This will be the range of the molecular weight of unknown sample.
