Interview Question in Mesh Analysis


 

Interview Question :: Combustion lab for chemistry.HELP


I did a lab in class where we had to watch the melting of a candle and write down our observations. We also had to place a wire mesh over the candle and observe what was happening, which was that the flame did not pass through it. We had the candle standing upright in a pan, which eventually we filled with water. After we put a flask over the candle and watched what happened. I saw that the water was rising and the flame increasingly went out as the water rose. The smoke from the flame dripped down the sides of the flask and just remained floating inside.

There were 2 questions on my lab i didnt understand:
- One requirement for combustion is the presence of fuel. Interpret your results from the steps and determine the other requirement.

-Based upon your analysis of the observations from these steps, what are two products of the combustion of the cnadle?

-What change in water level occurred in procedure 7?(when the water rose) Propose an explanation for this change.
Answers to "Combustion lab for chemistry.HELP"
RE: Combustion lab for chemistry.HELP?

Combustion requires fuel and oxygen.



The glass and water experiment was proof of that as the glass and water together starved the flame of any new oxygen so the candle went out.



The water in the inverted glass rose because the flame of the candle was consuming the oxygen of the trapped air. This loss of oxygen through combustion lowered the atmospheric pressure in the glass. The atmospheric pressure outside the glass was normal and that pressure in the surface of the water outside the glass caused the water to rise up inside the glass where there was no longer enough pressure to stop it from doing so.



Don't get the idea the oxygen in the glass was destroyed by the combustion, it was simply removed from the atmosphere inside the glass and converted into a more compact form (ash and CO2 mostly).
 
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