Calculate the vapor pressure at 298K above an aerosol mixture consisting of 30% w/w of aerosol propellant 114 (mol.wt = 170.9) with vapor pressure of 1.90 imes 105 ext Nm⁻² and 70% w/w of propellant

Let's assume a total mass of 100 g for the mixture.
Mass of propellant 114 ($m_{114}$) = $30\%$ of 100 g = 30 g
Mass of propellant 12 ($m_{12}$) = $70\%$ of 100 g = 70 g

Molar mass of propellant 114 ($MW_{114}$) = 170.9 g/mol
Molar mass of propellant 12 ($MW_{12}$) = 120.9 g/mol
Moles of propellant 114 ($n_{114}$):

Moles of propellant 12 ($n_{12}$):

Total moles ($n_{total}$):

Mole fraction of propellant 114 ($X_{114}$):

Mole fraction of propellant 12 ($X_{12}$):

Pure vapor pressure of propellant 114 ($P_{114}^\circ$) = $1.90 \times 10^5 \text{ Nm}^{-2}$
Pure vapor pressure of propellant 12 ($P_{12}^\circ$) = $5.85 \times 10^5 \text{ Nm}^{-2}$
Partial pressure of propellant 114 ($P_{114}$):

Partial pressure of propellant 12 ($P_{12}$):

Total vapor pressure ($P_{total}$) = $P_{114} + P_{12}$

The total vapor pressure is $\boxed{4.93 \times 10^5 \text{ Nm}^{-2}}$.

• Calculate the vapor pressure (in Pa) at $20^\circ\text{C}$ above an aerosol mixture consisting of $30\%$ w/w of HFA 134a (tetrafluoroethane, molecular weight 102) with a vapor pressure of 68.4 psig and $70\%$ w/w of HFA 227 (heptafluoropropane, molecular weight 170) with a vapor pressure of 56.0 psig. Assume ideal behaviour. NOTE: Psia = Psig + 14.7, 1 Psia = 6894.74 Pa

For HFA 134a:
$P_{134a}^\circ (\text{psia}) = 68.4 \text{ psig} + 14.7 = 83.1 \text{ psia}$
$P_{134a}^\circ (\text{Pa}) = 83.1 \text{ psia} \times 6894.74 \text{ Pa/psia} = 572953.554 \text{ Pa}$
For HFA 227:
$P_{227}^\circ (\text{psia}) = 56.0 \text{ psig} + 14.7 = 70.7 \text{ psia}$
$P_{227}^\circ (\text{Pa}) = 70.7 \text{ psia} \times 6894.74 \text{ Pa/psia} = 487430.798 \text{ Pa}$

Let's assume a total mass of 100 g for the mixture.
Mass of HFA 134a ($m_{134a}$) = $30\%$ of 100 g = 30 g
Mass of HFA 227 ($m_{227}$) = $70\%$ of 100 g = 70 g

Molar mass of HFA 134a ($MW_{134a}$) = 102 g/mol
Molar mass of HFA 227 ($MW_{227}$) = 170 g/mol
Moles of HFA 134a ($n_{134a}$):

Moles of HFA 227 ($n_{227}$):

Total moles ($n_{total}$):

Mole fraction of HFA 134a ($X_{134a}$):

Mole fraction of HFA 227 ($X_{227}$):

Partial pressure of HFA 134a ($P_{134a}$):

Partial pressure of HFA 227 ($P_{227}$):

Total vapor pressure ($P_{total}$) = $P_{134a} + P_{227}$

Rounding to three significant figures:

The total vapor pressure is $\boxed{5.23 \times 10^5 \text{ Pa}}$.