Hi, This is a post lab question and I don\'t have any measured values yet. Howev

Question

Hi,

This is a post lab question and I don't have any measured values yet. However, I would like to have some ideas of what the answer would be like.

Thank you very much for your help in advance!

Question:s 1. If the outside of the flask is not dried after vaporizing the liquid, will the molar mass of the compound be too high or too low? Explairn. The moar mass witl be tuo hgh Decause if the flask is not dried after vaporizing the liauid from the flask, the no istu re wil?e added and gve the heigher weight of the sample than actual weignt 2. Suppose you assumed that the atmospheric pressure was one atmosphere instead of the pressure that you recorded. Describe the error that would occur in reporting the molar mass. 3. If the volume of the vapor had been assumed to be 125 ml instead of your measured volume, calculate the percent error that would have resulted in the reported molar mass of the compound 4. If all of the unknown liquid does not vaporize in the 125 mL flask, will the reported molar mass be too high or too low? Explain. 5. Suppose the thermometer is mis-calibrated and reads 0.3 oC higher than actual. What effect does this err calibration have on the reported molar mass of the compound? or in 146

Explanation / Answer

Based on ideal gas equation,

Pressure x volume = (mass of liquid/molar mass) x gas constant x temperature

1. If the outside of the flask is not dried, the mass of liquid would be calculated higher than the actual value. Therefore, the molar mass would also be greater than then actual value. molar mass is directly proportional to the liquid mass.

2. If atmospheric pressure was assumed to be 1 atm, instead of measured value. The resulting molar mass would be lower than the actual value as pressure is inversely proportional to the molar mass.

3. If the volume of flask is taken as 125 ml instead of measured volume. The resulting molar mass would be lower than the actual value as volume is inversely proportional to the molar mass.

4. If not all of the liquid is vaporized in the flask. The mass of liquid calculated would be lower. Therefore, the resulting molar mass would also be lower. molar mass is directly proportional to the liquid mass.

5. If thermometer reads 0.3 oC higher than actual value. Therefore, the molar mass would also be greater than then actual value. molar mass is directly proportional to the temperature.

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