A gas and some powder are sealed in a hollow cylinder of internal volume 50 cubic cm at a pressure of 1000kPa. This volume was reduced to 20 cubic cm at a constant temperature, causing the pressure to rise to 400 kPa. Use these results to calculate the volume of the powder.
2006-07-30 12:59:05 · 8 answers · asked by surani_ud 3 in Science & Mathematics ➔ Physics
Sorry it isn't 1000 kPa but 100Kpa.
2006-07-30 13:03:14 · update #1
By the way, this isn't my homework. This is just a question I saw and it interested me. I did this last year in physics and can't figure out how I did it.
2006-07-30 13:05:19 · update #2
I know a powder is a solid! The question is asking for the volume of the powder. I know you have to subtract the gas volume or something like that.
2006-07-30 13:06:47 · update #3
Does anyone even read these additional details!
2006-07-30 13:25:25 · update #4
The powder is incompressible; let's call its volume x cc. To start with then, the volume of the gas is 50-x cc. When the pressure is 4 times as great, the volume of the gas is 20-x. So Boyle's Law says that 20-x=(50-x)/4, this is 12.5-x/4. Adding x/4 to both sides, 20-3x/4=12.5, so 3x/4=7.5 so x=10cc.
2006-07-30 14:40:40 · answer #1 · answered by zee_prime 6 · 2⤊ 1⤋
I suspect you are asking us to do your homework, but....
The scenario you propose is not possible. A 50 cc cylinder containing a gas at 1000 kpa would have an internal pressure of 2500 kpa if the volume was decreased to 20 cc - assuming constant temperature.
The volume of the powder would be the same at 0, 400, 1000 or 2500 kpa.
The volume of the powder remains constant, but you didn't tell us what the volume of the powder was at t0. If you knew how much powder was in the gas at 1000 kpa, then you could calculate the volume of gas, or vice versa. But not without the missing information or impossible physics.
EDIT - Did you know the "Additional Details" that you provided don't show up on the screen Yahoo gives you to answer the question? I didn't either!
Anyway, now that we know from your additional detail that the starting pressure was 100 KPa and not 1000 KPa, you can solve for the constant volume powder using Boyle's law. The next 3 answers are correct.
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2006-07-30 20:07:49 · answer #2 · answered by minefinder 7 · 0⤊ 0⤋
Let y be the volume of the powder.
(50 - y) is the initial volume of the gas.
(20- y) is the final volume of gas, assuming powder volume is not changed due to pressure.
Temperature remains the same.
P2/ P1 = V1/ V2 = 4. (Given)
(50 - y) = 4 (20- y) = 80 - 4y
3y = 80 - 50 = 30
y = 10 cubic centimeter.
2006-07-31 02:50:24 · answer #3 · answered by Pearlsawme 7 · 0⤊ 0⤋
Unfortunately 400kPa is less than 1000kPa!
Here is something that will work on any values (any correct values!).
Volume powder = ((final pressure x final cylinder volume) - (Initial pressure x initial cylinder volume)) / (final pressure - initial pressure)
Be careful with the brackets it is hard to do formulas on this site. If you need a better looking equation and an explanation of boyles law and how I got to this then email me through my profile.
Yees I do read additional details but not while I am writing. I think I have done enough work though. You can put the figures in.
2006-07-30 20:29:14 · answer #4 · answered by slatibartfast 3 · 0⤊ 0⤋
This is pretty straightforward. You know that at first you have 50cc and 100kPa, and that afterwards you have 20cc and 400 kPa. You also know that the gas volume must be 1/4 of what it was to raise the pressure 4 times. You must eliminate the volume of the powder to balance the equation's two sides.
The powder volume must be 10cc because then by subtraction of this constant volume, your gas goes from 40cc to 10cc and the pressure from 100kPa to 400kPa. This equation falls apart just looking at it.
2006-07-30 20:25:25 · answer #5 · answered by aichip_mark2 3 · 0⤊ 0⤋
Volume of powder wont change, its only the gas that changes volume.......:)
2006-07-30 20:04:01 · answer #6 · answered by Zaphod B 2 · 0⤊ 0⤋
Powder is a solid, it does not expand.
2006-07-30 20:03:23 · answer #7 · answered by Doggzilla 6 · 0⤊ 0⤋
do your own homework
2006-07-30 20:02:20 · answer #8 · answered by matt83840 5 · 0⤊ 0⤋