# MOLECULAR WEIGHT OF A VOLATILE LIQUID-Lab report

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Introduction

MOLECULAR WEIGHT OF A VOLATILE LIQUID CHEMISTRY HL JAIME CASTRO A. 10-2 PRESENTED TO: KEITH RIGBY ANGLO COLOMBIAN SCHOOL EXPERIMENTAL SCIENCES DEPARTMENT RESULTS: Table1. Showing the data recorded during the experiment Trial 1 2 Mass of flask /(g) �0.01g 112.86 112.86 Mass of flask and gas /(g) �0.01g 113.66 113.66 Mass of gas /(g) �0.01g 0.80 0.80 The volume of the flask was of 325 (� 2.5) cm3 which equals 3.25x10-4 (� 2.5 x10-6 )m3, the value of the volume will now only be considered in SI units. The temperature was of 92 �0.1�C which equals 365�0.1�K, the value of the temperature will now only be considered in SI units. The Pressure will be considered as the atmospheric pressure of Bogota which is 75 kPa which equals 75000 Pa, the value of the pressure will now only be considered in SI units. ...read more.

Middle

To use this law we can consider the following values for volume, pressure and temperature; the value of the constant is 8.314 when working with SI units. Temperature: 365�0.1�K Volume: 3.25x10-4 � 2.5x10-6 m3 Pressure: 75000 Pa So if we use the previously established values in the equation we will get the number of moles of gas inside the flask. To calculate the percentage uncertainty of this value we need to add up the percentage uncertainty of the pressure, the temperature and the volume Percentage uncertainty of the volume Uncertainty: � 2.5 x 10-6 m3 Volume: 3.25 x 10-4 m3 Percentage uncertainty = 0.77% Percentage uncertainty of the temperature Uncertainty: �0.1�K Temperature: 365�K Percentage uncertainty = 0.03% So the percentage uncertainty of the number of moles of the gas is of 0.8%. ...read more.

Conclusion

CONCLUSION: Taking in count that the liquid used in this experiment was a cycloalkane and that the empirical formula of cycloalkanes is, we can determine what cycloalkane was used by just dividing the molar mass of the liquid by the empirical mass of cycloalkanes. The result of this division was 7.1 which tells us that the molecular formula for the cycloalkane used in the experiment is which is the molecular formula for cycloheptane, therefore we can conclude that the cycloalkane used in this practical was cycloheptane. EVALUATION: The total percentage uncertainty of this practical was of 2.05% which is a really small percentage which makes our results very accurate. However I can suggest repeating the practical for 2 or 3 times so that an average of the results can be obtained and the possibility of a random error can be reduced. ?? ?? ?? ?? ...read more.

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry section.

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