Chem 142 - Lab 5 - Molar Mass of a Low Boiling Liquid

Chem 142 - Lab 5 - Molar Mass of a Low Boiling Liquid -...

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DATA AND CALCULATIONS A. Unknown # 1 Run 1 Run 2 Run 3 Mass of flask + cap + air 47.54 - - Mass of flask + cap + vapor 47.51 47.51 47.510 B. atm Barometric pressure 727.11 mm Hg = 0.96 K Sample temperature 100 C = 373 K Water (room) temperature 22.2 C = 295.2 Mass of flask + cap + water 173.79 g Density of water at RT 1 g/mL Volume of Flask, L 0.13 Name: Alice Hsieh Lab Partner: Hieu Duong 1. Calculate the volume of the flask.(2 pt) Mass of flash, cap and water = 137.785g Mass of flash, cap and water - mass of flask and cap = mass of water Mass of water = 173.785 - 47.536 = 126.249g Volume of flash = (mass of water) ( volume of water) (mass of water) = (126.249) 0.99777 = 126.531mL EXP 5: MOLAR MASS OF A LOW BOILING LIQUID Grading WebAssign prelab: 5 pts This template: 30 pts Lab Notebook Duplicate: 5 pts By signing below, you certify that you have not falsified data and that you have not plagiarized any part of this lab report. Failure to sign this declaration will cost you 5 points. Signature: Purpose and Method Things to think about: What is the goal of this experiment? Explain how it is accomplished. What is the general method (not step by step detailed procedure) that you will be using to achieve this goal? How will you process the data that you record in lab? (What calculations will you use and how do you obtain all of the values to plug into those equations?) (5 points) The objective of this experiment is to determine the molar mass of an unknown liquid. We will accomplish this by using the Dumas method, which is to heat a liquid until it changes to the gaseous state. When the liquid is at gaseous state, we can measure its peressure, volume and temperature. From these measurements, we can calculate the molar mass of the sample by using the ideal gas law, PV = nRT. Once we have calculated the molar mass, we can identify the unknown from a list of possible compounds. We will record the mass of flask, cap and air and the mass of flask, cap and vapor. By calculating the density of air from
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This note was uploaded on 10/27/2010 for the course CHEM 142 taught by Professor Zoller,williamh during the Winter '07 term at University of Washington.

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Chem 142 - Lab 5 - Molar Mass of a Low Boiling Liquid -...

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