Gas Law Problems: Calculating Volume of 2.0g He at 25°C & 775 mm Pressure

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Homework Help Overview

The discussion revolves around calculating the volume of 2.0 grams of helium gas at a specified temperature of 25°C and pressure of 775 mmHg, utilizing the ideal gas law.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the ideal gas law equation and the need to calculate the number of moles from the given mass of helium. Questions arise regarding the universal gas constant and its value, as well as the necessity of unit conversions for pressure.

Discussion Status

Some participants have provided guidance on the ideal gas law and the importance of unit consistency. There is an ongoing exploration of the calculations involved, with no clear consensus on the final answer yet.

Contextual Notes

Participants note the need to convert pressure from mmHg to pascals for proper calculations, and there is uncertainty regarding the correct application of the gas law equation.

blackjack18
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what volume is occupied by 2.0 g of He at 25 degrees C and a pressure of 775 mm?
 
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Pv = nRT

P = pressure
v = volume
n = number of moles
R = universal gas constant
T = temperature.

Calculate how many moles are in 2.0 grams of helium, divide both sides of the equation by P.

Solve.

EDIT: Remember to have your units correct, IE Kelvin, kilograms etc
 
what is the constant? or is there one? if so, how do i determine what it is?
 
R is the universal gas constant. It is always the same. In si units, it is: 8.314472 Joules per mol kelvin.
 
ok, I am not sure about this, but is the answer 1.59?
 
What did you use as your numbers?
 
775=0.5(constant)(298), then divided by 775
 
That equation is: p = nRT
You need volume on the left hand side to solve for it.
Also, you wrote in the question description that pressure = 775mm, I am going to assume that this is mmHg.
You are going to need to convert this to pascals.
 

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