Preview

determining mass of a voltaile liquid

Good Essays
Open Document
Open Document
334 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
determining mass of a voltaile liquid
Discussion
In this experiment, the molar mass of two volatile liquids – methanol and an unknown liquid – were calculated for through the Dumas Method.
Initially, the sets of Erlenmeyer flasks with aluminum foil and rubber bands were weighed. Next, volatile liquids were placed in 125mL Erlenmeyer flasks and covered with aluminum foil, but small holes were made into the foil. The flask was then heated in a water bath until all of the liquid evaporated. The flask was then removed, and weighed again after being cooled to room temperature.
To determine the molecular weight of the liquids, the mass of the condensed vapour is needed. This is achieved through the heating and cooling down of the flask – because the holes made in the foil allowed the excess vapour to escape, the methanol/unknown vapour pushed out the extra vapour and oxygen gas. When the flask was cooled down, the methanol/unknown vapour condensed – this resulted in the increase in mass of the flask when it was weighed after being cooled down. The mass of the condensed vapour is equal to the difference between the initial and final masses of the flask. Due to the assumption that the volatile liquids obey the Ideal Gas Law: PV=nRT, where n is equal to the mass of the substance divided by the molar mass – giving M=mRT/PV, the molecular weight could then be calculated for.
The experimental results revealed an average molar mass of 31.10g/mol for methanol (theoretical value of 32.04g/mol) and an average molar mass of 60.28g/mol for unknown # 20. which is closest to the molar mass of iso-propanol, 60.10g/mol. The differences in the molar masses of the experimental values and theoretical values may have been to sources of error such, as weighing the flask before it has fully cooled down to room temperature, or allowing too much vapour to escape from the flask during heating. Each of these factors would result in a higher or lower molecular weight than the theoretical value.

You May Also Find These Documents Helpful

  • Good Essays

    Ap Chemistry Lab Report

    • 678 Words
    • 3 Pages

    4. When vaporized, the volatile liquids used in this experiment do not behave exactly as ideal gases. How would this tend to affect your calculated molecular weight?…

    • 678 Words
    • 3 Pages
    Good Essays
  • Good Essays

    CHM130 Lab 6

    • 1556 Words
    • 6 Pages

    - Each liquid that was used in Part I has its own independent density. Density being the relationship between the mass and volume of a substance. In this portion of the lab we explored relative density, each liquid compared to the others. The corn syrup was the most dense, in comparison to the other liquids. Whereas the vegetable oil was the least dense compared to the other liquids. The liquids in between followed this same principle in their respective orders.…

    • 1556 Words
    • 6 Pages
    Good Essays
  • Satisfactory Essays

    Year 11 Chemistry Lab

    • 531 Words
    • 3 Pages

    A series of measurements are made in order to determine the molar mass of an unknown gas. First, a large flask is evacuated and found to weigh 134.567 g. it is then filled with the gas to a pressure of 735 torr and 31°C and reweighed; its mass is now 137.456 g. Finally, the flask was filled with water at 31.0 °C and found to weigh 1067.9 g. (The density of water at this temperature is 0.977 g/mL.) Assuming that the ideal gas equation applies, calculate the molar mass of the unknown…

    • 531 Words
    • 3 Pages
    Satisfactory Essays
  • Better Essays

    AP phyiscs lab

    • 893 Words
    • 4 Pages

    III. Procedure- The first thing one must do to identify which substance is which is to calculate the densities. To do this, one must take the mass and volume of each individual substance. Starting with mass, one can use the triple beam balance. Make sure the balanced is zeroed. Once that is true, place the object onto the balance a carefully find the mass of the object. Repeat and record the results found of each individual substance. To find the volume, one can use the water displacement method. One will fill up a graduated cylinder with water to a specific amount. 20 mL is sufficient. Once completed, one will drop one of the substances into the graduated cylinder and record how far the water level rises. If it starts at 20mL and rises to 22mL then the volume of the substance is 22mL minus 20mL, so 2mL. Repeat and record the results found of each individual substance.…

    • 893 Words
    • 4 Pages
    Better Essays
  • Satisfactory Essays

    Chem Lab 2 Report

    • 942 Words
    • 9 Pages

    Purpose: In this experiment I will determine the mass, density, volume, lengths and temperatures of different objects and liquids to help me better understand the importance of Chemistry and how Chemistry plays a big role in our everyday lives.…

    • 942 Words
    • 9 Pages
    Satisfactory Essays
  • Good Essays

    molar mass ap chem

    • 1051 Words
    • 6 Pages

    Molar masses, can be seen and used daily in chemistry. In this lab, the ideal gas law helps determine and evaluate the molar mass of gases and volatile liquids. The ideal gas law compares four properties of a gas which include pressure, volume, moles, and temperature. During this experiment, the moles would be unknown, in effect the student must use a substance mass divided by its molar mass. With this, the ideal gas law can be arranged in an equation fit for helping the student determine the molar mass of a gas.…

    • 1051 Words
    • 6 Pages
    Good Essays
  • Good Essays

    Cyclohexane Lab Report

    • 1767 Words
    • 8 Pages

    Abstract: The purpose of this experiment is to determine the molar mass of an unknown solid. The freezing point of a solvent (Cyclohexane) was determined, and compare to the freezing point of Cyclohexane with the addition of two different concentration of unknown solid. The pure substance of Cyclohexane has defined physical properties. However, when a solute is added these properties are determined by the amount of solute added, also known as colligative properties. The temperature of the freezing point was lowered when the solid was added and it decreased as the concentration of the solid increased. The molality of the solute was determined, which was then used to calculate the molar mass of the solid for both trials. An average of the molar mass of…

    • 1767 Words
    • 8 Pages
    Good Essays
  • Good Essays

    Limiting Reactant Lab

    • 1092 Words
    • 5 Pages

    A piece of filter paper was placed on the funnel and moistened with distilled water. With the aspirator on, the contents of flask 1 was poured into the funnel. The flask was rinsed out with distilled water and poured into the funnel in order to get most of the salts out of the funnel. The aspirator sucked the filtrate through the filter funnel. Once most of the liquid has been removed from the filter funnel, but the solid was still wet, 10 Ml of ethanol was added to the solid in the filter funnel. The ethanol was sucked through the filter funnel. The aspirator continuously ran in order to dry the solid on the filter funnel. Five vials were obtained and labeled with name, reaction number, and the flask number. The empty vials were weighed and their mass was recorded. When the solid was dry enough to remove from the filter funnel, the aspirator was turned off and the filter paper was removed from the suction flask. A spatula was used to gently remove the solid from the filter paper and placed into the corresponding vial. This process was repeated for all five Erlenmeyer flasks. Once completed, the vials with the solid contents were massed. After a week of drying, the vials were obtained and massed again. A graph using Excel was…

    • 1092 Words
    • 5 Pages
    Good Essays
  • Powerful Essays

    Chem 151 Gas Behavior

    • 1294 Words
    • 6 Pages

    In this experiment, we first measured the mass of an empty flask using the balance for our…

    • 1294 Words
    • 6 Pages
    Powerful Essays
  • Satisfactory Essays

    Unknown liquid

    • 264 Words
    • 2 Pages

    III. Procedure: 1.We massed an empty 10mL graduated cylinder to the nearest .01g. 2.Then, we filled the graduated cylinder with 4.0-5.0 mL of distilled water, 3.massed it to the nearest 0.1 ml and 4. recorded the data. Then to determine the density of the unknown liquid; we repeated the steps.…

    • 264 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Raccoon

    • 413 Words
    • 2 Pages

    First of all, a flask was taking out and filled in with 15ml of water. The mass of the flask & water was determined and recorded. Then, an Alka Seltzer tablet was filled in the water. After a while, placed the flask & water & Alka Seltzer tablet on to the balance pan, the mass of the whole system was determined. This procedure was for the open system.…

    • 413 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Production

    • 595 Words
    • 3 Pages

    2. Add 2-3 g of sodium hydrogen carbonate to the evaporating dish. Measure the mass of the sodium hydrogen…

    • 595 Words
    • 3 Pages
    Satisfactory Essays
  • Good Essays

    Steam Distillation

    • 630 Words
    • 3 Pages

    The purpose of this experiment is to extract Eugenol from Cloves using steam distillation as a purification technique and to transfer Eugenol from the aqueous phase to the MeCl2 phase. With steam distillation, the boiling point of a mixture of immiscible liquids is lower than the boiling points of the individual components. Water from the steam is one of the components of an immiscible liquid mixture. The vapor pressures of each of the components during the distillation are additive. And, the outcome is a co-distilled mixture of water and immiscible components. The organic components can be separated from water.…

    • 630 Words
    • 3 Pages
    Good Essays
  • Powerful Essays

    Diels Alder Experiment

    • 1208 Words
    • 5 Pages

    6 1.3mL of methanol was added to the vial as it was stirred at room temperature.…

    • 1208 Words
    • 5 Pages
    Powerful Essays
  • Good Essays

    Chem Pre-Lab

    • 635 Words
    • 3 Pages

    The mass of the sample is given by the mass of flask (52.87 g) subtracted from the mass of flask and sample (53.42 g).…

    • 635 Words
    • 3 Pages
    Good Essays

Related Topics