Finding the formula of CuO by reduction

 

       Diagram of apparatus set out

4. Add enough Ethanol to the mineral wool to wet it thoroughly but pour any excess liquid away before setting up. Make sure the apparatus is set up behind a safety screen or in a fume cupboard with the front pulled down.
5. Now carefully turn on the gas so it produces a stream of Ethanol. Vapour passing over the oxide. If liquid looks as if it might go over into the reduction tube turn the gas down and if this does not work take the apparatus apart and try to remove more liquid from the wool.
6. Once the meths vapour is passing in a controlled fashion over the oxide light the gas jet at the end of the reduction tube. (The gas must have passed over for at least 4-5 seconds). Turn the flame down to a reasonable size
7. Now heat the oxide strongly until it is completLy converted to Copper.
8. Remove the heat and allow the reduction tube to cool before turning off the gas stream passing through the apparatus.
9. Finally re-weigh the reduction tube containing Copper.

 Calculation of empirical formula

Weight of reduction tube =28.1730

Weigh of CuO= 2.3725

29.9958 – 28.1730 =1.8228

CuO + ethanol               Cu + H2O + Ethanol

     

Moles of Cu = 1.8228 =0.0284813

                            64

Moles of O = 2.3725 – 1.8228= 0.034356

Formula = CuO

Conclusion

The formula of Copper Oxide is CuO. From my results I have realised I have not got formula. The formula I have got is …..

Evaluation

There were many errors in my experiment. For example how do I know that all the Oxygen in the reduction tube was removed before the experiment? Perhaps there was still some in the tube. Next time I do the experiment I can check for oxygen by lighting a splint to see if there is any Oxygen. If there is know Oxygen the splint will go out the actual formula of Copper Oxide is CuO.Therefore from my results I can deduce that I have errors in the experiment. As you can see I have been left with too much Oxygen in the Compound CuO. Therefore next time I do the experiment I could heat it for longer so that all oxygen is removed from the compound. The colour change of CuO to Cu is black to green indication Oxygen has been lost. The colour change took time in my experiment. For more effective heating of the Copper Oxide next time I will spread the CuO thinly so it burns more efficiently.