Respuesta :
Answer: The mass difference between the two is 7.38 grams.
Explanation:
To calculate the number of moles, we use the equation given by ideal gas follows:
[tex]PV=nRT[/tex]
where,
P = pressure = 125 psi = 8.50 atm (Conversion factor: 1 atm = 14.7 psi)
V = Volume = 855 mL = 0.855 L (Conversion factor: 1 L = 1000 mL)
T = Temperature = [tex]25^oC=[25+273]K=298K[/tex]
R = Gas constant = [tex]0.0821\text{ L. atm }mol^{-1}K^{-1}[/tex]
n = number of moles = ?
Putting values in above equation, we get:
[tex]8.50atm\times 0.855L=n\times 0.0821\text{ L atm }mol^{-1}K^{-1}\times 298K\\\\n=\frac{8.50\times 0.855}{0.0821\times 298}=0.297mol[/tex]
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
- For air:
Moles of air = 0.297 moles
Average molar mass of air = 28.8 g/mol
Putting values in equation 1, we get:
[tex]0.297mol=\frac{\text{Mass of air}}{28.8g/mol}\\\\\text{Mass of air}=(0.297mol\times 28.8g/mol)=8.56g[/tex]
Mass of air, [tex]m_1[/tex] = 8.56 g
- For helium gas:
Moles of helium = 0.297 moles
Molar mass of helium = 4 g/mol
Putting values in equation 1, we get:
[tex]0.297mol=\frac{\text{Mass of helium}}{4g/mol}\\\\\text{Mass of helium}=(0.297mol\times 4g/mol)=1.18g[/tex]
Mass of helium, [tex]m_2[/tex] = 1.18 g
Calculating the mass difference between the two:
[tex]\Delta m=m_1-m_2[/tex]
[tex]\Delta m=(8.56-1.18)g=7.38g[/tex]
Hence, the mass difference between the two is 7.38 grams.
