2.4 Exercise 19

One process for decaffeinating coffee uses carbon dioxide $\left(M = 44.0 \text{g}/\text{mol}\right)$ at a molar density of about $14,600 \text{mol}/\text{m}^{3}$ and a temperature of about $60 ° \text{C}$. (a) Is CO₂ a solid, liquid, gas, or supercritical fluid under those conditions? (b) The van der Waals constants for carbon dioxide are $a = 0.3658 \text{Pa} \cdot \text{m}^{6} / \text{mol}^{2}$ and $b = 4.286 \times 10^{−5} \text{m}^{3} / \text{mol} .$ Using the van der Waals equation, estimate the pressure of $\text{CO}_{2}$ at that temperature and density.