What is the Mass Density of Air at 1 atm and -50°C?

In summary, the average molecular mass of air is 29 u, which can be used to calculate the mass density of air using the ideal gas law. However, in order to get an accurate result, it is important to carry the units through the equations and consider the relationship between mass and number of moles.
  • #1
jmb07
27
0
Average molecular mass of air is 29 u. What is the mass density of air at 1 atm and -50 degrees celsius??

This is what i have so far...

V=(NkT)/P so V= [(29u)(1.38E^-23)(-50 + 273)]/ 1 = 8.9 x10^-20

The mass is equal to 29u x (6.022 x 10^23) =1.75 x 10^25

density =m/v so = 1.96 x 10^44...and that is wayyyy off! The correct answer is like around 1, 2, or 3...i need some help. What am i doing wrong?
 
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  • #2
Try carrying your units through your equations. What does it mean to have a molecular mass of 29?
 
  • #3
uh...i know i could try to convert the 29u to (number of atoms)...but i don't have any molecular weight
 
  • #4
29u tells you something about the relationship between mass (which is connected to density) and the number of moles (which is connected to the ideal gas law that you're using).
 

FAQ: What is the Mass Density of Air at 1 atm and -50°C?

What is the relationship between temperature and mass density?

The relationship between temperature and mass density is an inverse one. As temperature increases, the mass density decreases and vice versa. This is because as temperature increases, the molecules of a substance start to move faster and take up more space, resulting in a decrease in mass density.

How does temperature affect the density of a substance?

Temperature has a direct effect on the density of a substance. As mentioned before, as temperature increases, the molecules of a substance spread out and take up more space, resulting in a decrease in density. On the other hand, as temperature decreases, the molecules move slower and become more tightly packed, leading to an increase in density.

What units are used to measure temperature and mass density?

The standard unit for temperature is degrees Celsius (°C) or Kelvin (K). Mass density is typically measured in units of grams per cubic centimeter (g/cm3) or kilograms per cubic meter (kg/m3).

How can temperature and mass density affect the behavior of a substance?

Temperature and mass density can greatly affect the behavior of a substance. For example, changes in temperature can cause substances to change states, such as from a solid to a liquid or a gas. Changes in mass density can also affect the buoyancy of a substance, as objects with a lower density will float on top of objects with a higher density.

Is there a limit to how high or low temperature and mass density can go?

Yes, there are limits to how high or low temperature and mass density can be. The highest possible temperature, known as absolute hot, is 1.416785(71)×10^32 K, while the lowest possible temperature, known as absolute zero, is 0 K. As for mass density, it can theoretically range from 0 (for a perfect vacuum) to infinity, but in reality, the density of most substances will fall within a certain range based on their physical properties.

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