Investigation of the Thermal Decomposition of Copper Carbonate

1434 Words3 Pages

Investigation of the Thermal Decomposition of Copper Carbonate

Aim:

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) + O2 (g)

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

The aim of this experiment is to prove which equation is correct. This can be done by volumetric analysis i.e. calculating the volume of gas produced. This is then compared to the calculated volume of gas produced in each equation and the equation with the nearest volume of gas is correct.

This is a thermal decomposition reaction and when an element like copper can form two oxides, which one forms is based on the stability of the compound formed. The more stable the compound, the more likely it is to form.

The stability of a compound with respect to its elements can be predicted by the Hf (molar heat of formation). This is the energy change when 1 mole of a compound is formed from its elements. If it is exothermic (negative), then the compound is stable with respect to its elements. If it is endothermic (positive), then the compound is unstable with respect to its elements. In general, the lower the value of Hf, the greater the energetic stability of the compound with respect to its elements.

The molar heat of formation of CuO is 155.2, and the molar heat of formation of Cu2O is 166.7. So it seems as though Cu20 will be the more stable compound. However, this fails to take into account the kinetic stability of a compound. The kinetic stability of a compound is caused by the activation energy required to cause it to react. The greater the activation energy required, the greater the kinetic stabili... ... middle of paper ...

... experiment and using the same apparatus again helps reduce the risk of error GRAPH

In this experiment if the volume produced is nearer to 242.9 cm then
It will mean that equation 1 is correct. If the volume of gases produced is nearer to 194.4 cm then equation 2 is correct. I predict that the most probable equation that is correct is equation 2.
Previous knowledge may also help to support this prediction as when anything combusts oxygen gas is never given off as a product because the oxygen is needed for the reaction.

References

- http://www.chemistry-react.org/go/Tutorial/Tutorial_4642.html

- L. Ryan (2000). Advanced Chemistry for You: Page 117

- E.N RAMSDEN (2000). A Level Chemistry 4th Edition: Page 151-6

- B. Ratcliff (2000) .editor. Chemistry 1: page 26-27

- http://science.widener.edu/svb/tutorial/avogadroslaw.html

Open Document