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secondary 4 | Chemistry
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Hi, could you kindly advise me on the correct answer and why so? Thank you so much.
Date Posted: 3 years ago
Views: 677
Good evening Candice! That will be at the 40 cm3 mark, since oxygen takes up 20% of air in general, meaning to say that 10 cm3 of oxygen is wasted in the formation of rust.
When air is used up, there will be fewer gas particles in the space and thus the pressure will decrease if the volume is unchanged. However, the pressure is supposed to remain the same before and after the volume change. Since the atmospheric pressure does not appear to change at all (the atmosphere is so huge), the pressure inside the tube would have to somehow reinstate its old pressure.
The only way this can happen is to allow the water to rise up the tube to occupy the lost spaces.
As such, the water level will rise up to the 40 cm3 mark because only 40 cm3 of gas will remain.
When air is used up, there will be fewer gas particles in the space and thus the pressure will decrease if the volume is unchanged. However, the pressure is supposed to remain the same before and after the volume change. Since the atmospheric pressure does not appear to change at all (the atmosphere is so huge), the pressure inside the tube would have to somehow reinstate its old pressure.
The only way this can happen is to allow the water to rise up the tube to occupy the lost spaces.
As such, the water level will rise up to the 40 cm3 mark because only 40 cm3 of gas will remain.
Good evening Mr Eric :) Thanks for the awesome explanation. Very clear and detailed. I got it now.
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Good evening Candice! For this question, I take a few things into consideration.
1. I assume that this experiment is conducted on Earth under standard air settings which contain 78% nitrogen, 21% oxygen and 1% other gases.
2. Oxygen is taken to be the gas which can react with iron; nitrogen does not react with iron (at least for your syllabus) and other gases, even if they react with iron, will make little contribution.
3. I assume that the diagram is not drawn to scale because the space above the 10 cm3 mark seems to be bigger than every other 10 cm3 interval.
4. I assume that the pressure inside the tube is lower than the atmospheric pressure (because the water level seems higher than it should).
1. I assume that this experiment is conducted on Earth under standard air settings which contain 78% nitrogen, 21% oxygen and 1% other gases.
2. Oxygen is taken to be the gas which can react with iron; nitrogen does not react with iron (at least for your syllabus) and other gases, even if they react with iron, will make little contribution.
3. I assume that the diagram is not drawn to scale because the space above the 10 cm3 mark seems to be bigger than every other 10 cm3 interval.
4. I assume that the pressure inside the tube is lower than the atmospheric pressure (because the water level seems higher than it should).
Date Posted:
3 years ago
Noted with thanks, Mr Eric :)
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