Dalton's Law And Archimedes Principle Lab Report

Charles Reverand

Mrs. Rick

Chemistry H

12 March 2018

Determining the Molar Mass of a Gas with Dalton’s Law and Archimedes’ Principle

Introduction

Archimedes’ principle describes the idea of buoyancy. The principle states that an upward force acts on an object when submerged in a gas or liquid.[1] When the object is at rest, this force, called the buoyant force, is equal and opposite to the force acting downwards on the object.[1] The buoyant force is caused by the pressure of the gas or liquid the object is in and increases the further down the object is in the fluid, as described by Boyle’s Law. This can be seen in the image below where a five kilogram weight has a buoyant force of 2 kilograms acting upon it. This causes the weight to measured

For this reason, three different molar masses were calculated. This ensures that calculations were accurate for each trial. The first trial saw a large percent error of 19%. This error was caused because a few bubbles of butane gas escaped the graduated cylinder, decreasing the volume of butane gas in the cylinder. The percent error associated with the second and third trial was much better than that of the first trial. At a value of 7.1% and 3.2% respectively, the error that occurred during the first trial did not persist into the rest of the trials. However, excess water on the lighter attributed to the error across all three trials. The excess water on the lighter gave it a larger mass when measured using the triple beam balance. Due to this, the mass of butane collected was slightly inaccurate, causing errors in the calculation of the molar mass of

The theoretical molar mass of butane was found by adding the molar mass of each element that makes up butane. This means that the molar mass of carbon was multiplied by four and added to the molar mass of hydrogen multiplied by ten, yielding a molar mass of 58.124g/mol. The calculated molar mass of butane was found by using the equation, M = (DRT)/P, where the density was found by dividing the mass of butane collected by the volume of butane in the graduated cylinder in liters and the pressure was the partial pressure in kilopascals of butane. After finding these two values, they were subtracted, divided by the theoretical molar mass of butane, and finally multiplied by