Determining the Relative Atomic Mass of Lithium

A-Level: Physics

Introduction

My aim of this experiment will be to determine the R.A.M using two separate methods

In the first method I will dissolve a piece of lithium of a known mass in water, I will then collect the hydrogen gas produced, which can be used to calculate the relative atomic mass of Lithium.

The balanced equation of our reaction is shown below;

2Li + 2H2O 2LiOH + H2

In the second method I will do a titration experiment of lithium hydroxide (produced in experiment 1)

The balanced equation of our reaction in experiment 2 is shown below;

LiOH + HCl LiCl + H20

Background Information

Lithium is an alkali metal in group 1 of the periodic table. It is a metallic element and does not decompose however it is highly in contact with many other substances. It can react violently with water, the humidity in air, and the moisture in other substances releasing hydrogen gas.

Apparatus

* Lithium (0.08g)

* Pan Balance

* Conical Flask

* Bowl

* Measuring Cylinder (250cm3)

* Delivery tube and Bung

* Goggles

* Filter

* Clamp


Method

I set up the apparatus as shown above. I placed water into the bowl (I used a big bowl because the measuring cylinder was 250cm3 which was too big to fit into a beaker). I made sure there was no air in the measuring cylinder and that it only contains water and I put it into the bowl of water over the delivery tube, I then got a clamp stand to hold the measuring cylinder.

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