Determination of the Valency of Magnesium

Determination of the Valency of Magnesium

Objectives:

In this experiment, we can know about the quantitative relations

between amounts of reactants and products of a reaction so that the

stoichiometry reaction can be determined by a known mass of magnesium

and a measured collection of hydrogen gas.

Introduction:

In chemistry, stoichiometry is the study of the combination of

elements in chemical reactions. Stoichiometry refers to the relative

number of atoms of various elements found in a chemical substance and

is often useful in characterizing a chemical reaction. The related

term stoichiometric is often used in thermodynamics to refer to the

"perfect mixture" of a fuel and air.Stoichiometry is often used to

balance chemical equations. In this experimet, a known starting mass

of magnesium and the measured collection of hydrogen gas will be used

to determine the reaction stoichiometry.

This experiment determines the stoichiometry of a reaction of

magnesium and HCl. The relationship between moles of magnesium reacted

and moles of hydrogen produced are plotted. Magnesium Ribbon is a

strip of Magnesium that is solid at room temperature. When mixed with

hydrochloric acid it produces Magnesium Chloride, which is a liquid

and Hydrogen gas.

The below is the equation that occurs:

Mg + XHCl à MgClx + [IMAGE]H2

The known amount of the magnesium is reacted with large excess of HCl

, and the volume of H2 is measured. As HCl is in excess, all the

magnesium will be consumed, and the yield of both MgClX and H2 depend

only on the amount of magnesium. A comparison of the amount of

hydrogen produced with the amount of magnesium consumed will enable X

value to be determined.

Apparatus and Materials :

· Magnesium ribbon

· HCl(0.5M)

· Burette (50cm3)

· Pipette (25cm3)

· Retort stand

· Electrical Balance

· Watch glass

· Beaker(500cm3)

· Gauze

· Funnel

· Rubber band

· Glass rod

· Thermometer