Solving a Take Home Quiz: Determining Gas Density

AI Thread Summary
To solve the gas density problem, start by recognizing that the mass of helium remains constant as temperature increases. Use the ideal gas law relation, which allows for the calculation of the volume ratio (V2/V1) based on the temperatures T1 and T2. Since density is mass divided by volume, substituting this into the equation reveals that the density will change proportionally with temperature when pressure is constant. Ultimately, the new density can be calculated without needing the actual mass or volume values. Understanding these relationships simplifies the problem significantly.
Cheapo2004
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Heres a problem on a take home quiz I am doing, but i can't figure out how to get past the first step?!

The density of helium gas at 0°C is 0.179 kg/m^3. The temperature is then raised to 100°C, but the pressure is kept constant. Assuming that Helium is an ideal gas, calculate the new density of the gas.

Heres the equations i have:
P1V1 / T1 = P2V2 / T2

In order to work this equation i need volume, but i have a density, here's the equation i think i need:

roe = m / V
(density = mass / volume)

How do i work this if i don't have mass or volume?!
 
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Cheapo2004 said:
Heres a problem on a take home quiz I am doing, but i can't figure out how to get past the first step?!

The density of helium gas at 0°C is 0.179 kg/m^3. The temperature is then raised to 100°C, but the pressure is kept constant. Assuming that Helium is an ideal gas, calculate the new density of the gas.

Heres the equations i have:
P1V1 / T1 = P2V2 / T2

In order to work this equation i need volume, but i have a density, here's the equation i think i need:

roe = m / V
(density = mass / volume)

How do i work this if i don't have mass or volume?!
You have to find the proportional increase in volume: V2/V1. You know P1 and P2 (they are the same. You know T1 and T2. All you have to find is V2/V1.

AM
 
You know the mass of the gas doesn't change. Try putting the density formula into the equation, you will find that they cancel out.
 

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