Using the van der Waals equation, the pressure of the sample of carbon dioxide at 85.0 °C with a molar volume of 4.89 L/mol is approximately 0.963 atm.
To calculate the pressure of a sample of carbon dioxide at 85.0 °C with a molar volume of 4.89 L/mol, we can use the van der Waals equation:
P = (RT)/(V - b) - (a/v^2)
where P is the pressure, R is the ideal gas constant (0.0821 L·atm/(mol·K)), T is the temperature in Kelvin (85.0 + 273.15 = 358.15 K), V is the molar volume (4.89 L/mol), a is the attraction constant (± value = 3.592), b is the size constant (0.0429).
Substituting the given values into the equation:
P = (0.0821 * 358.15)/(4.89 - 0.0429) - (3.592/(4.89^2))
Calculating the expression:
P = 0.963 atm
Therefore, the pressure of the sample of carbon dioxide at 85.0 °C with a molar volume of 4.89 L/mol is approximately 0.963 atm.