Gas mixture pressure: P tot = 46.588 atm
Additional information
Dalton's law of partial pressures indicates that the aggregate pressure of a gas mixture equals the total of the individual gases' partial pressures.
This can be expressed as:
P tot = P1 + P2 + P3....
Each gas's partial pressure represents its pressure within the mixture.
We calculate the pressure of He and CO₂ from the mixture and sum them to obtain the overall pressure. We apply the ideal gas equation:

Where:
P = pressure, atm, N / m²
V = volume, in liters
n = mole count
R = gas constant = 0.082 l.atm / mol K (for P = atm, V = liters) or 8.314 J / mol K (for P = Pa or N / m², V = m³)
T = temperature in Kelvin
n = N / No
n = moles
No = Avogadro's number (6.02 x 10²³)
n = m / M
m = mass
M = molar mass
M = 4 g / mol
m = 48.5 g
n = m / M
n = 48.5 / 4
n = 12.125 moles
PV = nRT

2. CO₂
M = 44 g / mol
m = 94.6 g
n = m / M
n = 94.6 / 44
n = 2.15 moles
PV = nRT

P tot = P He + P CO₂
P tot = 39.571 + 7.0167
P tot = 46.588 atm
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