The aim of this experiment is to prove which of these two equations is correct by measuring the volume of gas given off by the decomposition of CuCO3.

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Katherine Allen

Decomposition of Copper Carbonate

Introduction

Copper has two oxides, Cu2O and CuO.  Copper carbonate, CuCO3, decomposes on heating to form one of these oxides and an equation can be written for each possible reaction.

Equation 1:        2CuCO3 (s)  →  Cu2O (s)  +  2CO2 (g)  +  ½O2 (g)

Equation 2:        CuCO3 (s)  →  CuO (s)  +  CO2 (g)

Aim

The aim of this experiment is to prove which of these two equations is correct by measuring the volume of gas given off by the decomposition of CuCO3.

Background Theory

Cu2O is known as cuprous oxide.  It is a red crystalline material, which can be produced by electrolytic or furnace methods.  CuO is cupric oxide.  This, a black powder, can be prepared by the ignition of suitable salts such as the carbonate, the hydroxide, or the nitrate of copper, or by heating of cuprous oxide*.

 

The planning of this experiment requires previous knowledge about the mole.  The mole is the chemist’s unit of amount; it is the mass of substance that has the same number of particles as there are atoms in exactly 12g of carbon-12.  One mole of any substance, be it element or molecular compound, contains Avogadro’s number of atoms.  Avogadro’s number is a constant, L, and is approximately 6.02 x 1023 mol-1**.

Avogadro discovered that, at room temperature (25ºC) and pressure (1 atmosphere), all gases occupy that same volume.  One mole of any gas will occupy a volume of 24dm3.  This information is useful for working what amount of copper carbonate should be decomposed. Another essential equation will be required in order to do this:

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Moles = Mass

               Mr

Therefore:                                          

Mass = Moles x Mr


Katherine Allen

Calculating the Correct Mass

The best method would be to take one of the two equations and try to prove or disprove it.  Since Equation 2 has only 1 mole of every substance, this would be the easier one to work with in terms of ratio.  It can be said that:

“1 mole of ...

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