## Pressure of gasses

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305174946
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### Pressure of gasses

On page 151 of the 6th edition of our textbook there is an equation: P=dhg which solves for the pressure of a gas based on the height of a column of liquid and its density and gravity. I was wondering if we would need to know this calculation, if so can someone please explain it in depth because the explanation in the textbook slightly confuses me.

Kenan Kherallah 2C
Posts: 78
Joined: Fri Sep 28, 2018 12:17 am

### Re: Pressure of gasses

I dont think we will be using this equation since he hasnt mentioned it in lecture and all HW problems are solvable without the equation.

904914909
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

### Re: Pressure of gasses

I think stick to the formulas he has given us in lecture so far, bc this one hasn't been mentioned yet.

Mhun-Jeong Isaac Lee 1B
Posts: 54
Joined: Fri Sep 28, 2018 12:17 am

### Re: Pressure of gasses

Yeah just to confirm the above responses, Dr. Lavelle hasn't gone over that equation so I don't think we have to know that one. For now at least.

Jasmine Chow 1F
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### Re: Pressure of gasses

I don't think we will be using it. He hasn't mentioned it in lecture yet.

Chem_Mod
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### Re: Pressure of gasses

This is more of a physics topic but if your interested this is the general idea:
To calculate the weight of the liquid we use the equation: weight (force)=mg (mass x gravity constant). The mass of the liquid can be determined using both the volume of the liquid and its density (m=Vd : where V=volume and d=density). Combining these equations we now get F=Vdg.The volume of a cylinder of liquid can be determined using the geometric formula V=A (of the circle) x h (height of the liquid). Using this equation we now get: F=Ahdg
Now, the definition of pressure is Force/Area, so combining the equations above we get P=(Ahdg)/A which when simplified yield P=hdg Tadaaaaa.