Chapter 10, Problem 12RQ

1. 12. The ideal gas law assumes that molecules bounce around and have negligible volume themselves. This is not always true. To compensate for the simplifying assumptions of the ideal gas law, the Dutch scientist Johannes van der Waals developed a “real” gas law that uses several factors to account for molecular volume and intermolecular attraction. He was awarded the Nobel Prize in 1910 for his work. The van der Waals equation is as follows:

$\left(P+\frac{a{n}^2}{V^2}\right)\left(V-bn\right)=nRT$

P, V, n, R, and T are the same quantities as found in the ideal gas law. The constant a is a correction for intermolecular forces [atm L²/mol²], and the constant b accounts for molecular volume [L/mol]. Each of these factors must be determined by experiment.

Create a worksheet using the provided template. The molecular weight, a, and b should automatically fill in after the user selects the type of gas in cell B7. The user will also set the quantity of gas and the temperature of the system.

Next, create a column of volume beginning in A21 at 0.5 liters and increasing in increments of 0.1 liters to a volume of 5 liters.

In column B, calculate the pressure (P, in atmospheres [atm]) using the ideal gas law.

In column C, calculate the pressure (P, in atmospheres [atm]) using the van der Waals equation.

Hint

Use data validation and lookup expressions using the data found in the table located in E7 to H26 in the workbook provided.