Calculating Molar Mass Percent Error in Butane Lab Results

In summary, the conversation discussed the results of a lab on the collection of butane over water to calculate its molar mass. The measured molar mass was significantly lower than the accepted value, resulting in a high percent error of -70%. The reason for this high error is likely due to the difference in conditions between the accepted value (gathered at STP) and the lab (accounting for vapor pressure but not entirely eliminating error). It was also noted that speculation over the cause of the error is not productive without being able to eliminate human error.
  • #1
SkittlesGal
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Homework Statement


I did a lab on the collection of butane over water to calculate the molar mass. In one trial, the measured molar mass was 20 g/mol, however, the accepted value for butane is 58.14 g/mol. This means the percent error is -70%. Why is it so high, assuming there is no relevant human error causing it?


Homework Equations


n=PV/RT
(measured value-accepted value)/accepted value


The Attempt at a Solution


I think it's so high because the accepted value is gathered at STP, and although the vapor pressure was accounted for, it still does not entirely account for the error.
 
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  • #2
Huge error for a single trial is meaningless. Speculating over what have happened when you can't eliminate human error is a waste of time.
 

1. What is molar mass percent error?

Molar mass percent error is a measure of the accuracy of an experimental value for the molar mass of a substance compared to the accepted or theoretical value. It is calculated by taking the absolute difference between the experimental and accepted values, dividing it by the accepted value, and then multiplying by 100 to get a percentage.

2. Why is molar mass percent error important?

Molar mass percent error is important because it allows scientists to determine the reliability and accuracy of their experimental data. It can also indicate if there were any errors or inconsistencies in the experimental procedure.

3. How is molar mass percent error different from percent error?

Molar mass percent error specifically refers to the accuracy of the molar mass of a substance, while percent error is a more general term that can be used to measure the accuracy of any experimental value compared to the accepted value.

4. What factors can contribute to molar mass percent error?

There are several factors that can contribute to molar mass percent error, including human error in measurement or calculation, variations in experimental conditions, and incorrect assumptions or approximations in the experimental procedure.

5. How can molar mass percent error be reduced?

Molar mass percent error can be reduced by improving the accuracy and precision of measurements, ensuring consistent experimental conditions, and minimizing assumptions or approximations in the experimental procedure. It is also important to carefully analyze and understand any potential sources of error and make adjustments accordingly.

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