Chem1010 Chemistry : Discovery Of Assessment Answers

On Joseph Priestly ( discovery of oxygen)

1.Evaluate the methodology chosen based by:

Justify the method chosen based on the subject of the investigation and the context, for example: experimental testing, fieldwork, locating, and using information source.....etc.

Evaluate the relevance of the investigation by considering the peer-reviewed literature in the area of the study.

Justify the suitability of the type of data that was collected

2.Propose three areas of future investigation that could add to the work of the chosen scientist

1.Methodology

Priestley performed his experiments and analysis of the properties of different airs using an inverted container that was placed on a raised platform. The apparatus therefore had the ability to capture various gases as produced by the numerous experiments below it. The apparatus could also be placed inside mercury or a pool of water, well-sealed. A gas would then be tested to determine if can support life or sustain a flame. The results from the experiments showed that in case a mouse died and a flame went off, that symbolized lack of air. When a green plant is put in the jar and then exposed to sunlight, the mouse would breathe hence stay alive and the flame would also burn. Priestley realized that the trouble that the animal undergoes is repaired by the plant. He therefore witnessed that plants released oxygen into the air (Smith, 2011).

More experiments were done using a glass burning lens of width 12 inches. He focused light on a lump of reddish mercuric oxide in an inverted glass container. The container was placed pool full of mercury. From the experiment, he realized that the gas that was released was 5 or 6 times better than the common air. More experiments were performed and the results was that the air emitted enabled flame to burn intensely and also the mouse breathed it hence keeping it alive. He also realized that the air kept the mouse alive and also maintained the burning flame at a rate up to four times more than the common air. He named it dephlogisticated air given that it perfectly supported combustion. The air also had no phlogiston and could therefore absorb the maximum amount of it during burning.

Relevance of the investigation

Joseph Priestley performed several experiments which ultimately led to the discovery of oxygen in 1774. The culmination of the experiments made Priestley discover that air is not just an elementary substance but a mixture or composition of several gases. Among the gases in the mixture include a highly reactive and colorless gas which he called dephlogisticated air. The name would later be changed by renowned chemist Antoine Lavoisier as Oxygen. Different scholars have carried out studies and experiments aimed at discovering air. During his experiments, Carl Wilhelm Scheele had also isolated a similar gas to the one Priestley achieved. Carl called this gas fire air. This was because it could support combustion. The relevance of this discoveries were made known later in the 18^th century when there was need to find out what really happens when a substance burns. Priestley discovery therefore acted as a basis for Antoine Lavoisier to disprove the existence of phlogiston. The test for phlogiston would still follow Priestley idea of putting a mouse in a container and measuring how long it lived.

Suitability of data collected

From the above experiments, it was realized oxygen is able to intensely support combustion and is also required by plants and animals for breathing. The data collected was used to determine how long a mouse can live in the container and how long a flame can burn. The information revealed that a flame burnt longer and more intensely in the presence of oxygen as compared to common air (Sternbach, & Varon, 2014).

2: Future investigations.

The following related proposed investigations could also add to the work of Priestley;

1. Investigations into the existence of phlogiston.
2. Isolation of carbon (IV) oxide.
3. Chemical revolution

References

Smith, W. D. A., (2011) A history of nitrous oxide and oxygen anaesthesia part I: Joseph Priestley to Humphry Davy. 11^th ed. London: British institute of Anaesthesia, 37(10), pp.790-798.

Sternbach, G. L. and Varon, J., (2014) The discovery and rediscovery of oxygen. 20^th century Journal of emergency medicine, 28(2), pp.221-224.

International Historic Chemical Landmark, (2018, November 18). Discovery of oxygen. Retrieved from https://www.brlsi.org/node/18153

American Chemical Society International Historic Chemical Landmarks, (2014, January 15) Discovery of Oxygen by Joseph Priestley. Retrieved from https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/josephpriestleyoxygen.

Experiments and Observations on different kinds of air, (2018, November 17) Joseph Priestley. Retrieved from https://googleweblight.com/i?u=https://www.juliantrubin.com/bigten/oxygenexperiments.html&hl=en-KE