The critical temperatures \((\mathrm{K})\) and pressures \((\mathrm{atm})\) of a series of halogenated methanes are as follows: $$ \begin{array}{lcccc} \text { Compound } & \mathbf{C C l}_{3} \mathbf{F} & \mathbf{C C l}_{2} \mathbf{F}_{2} & \mathbf{C C I F}_{3} & \mathbf{C F}_{4} \\ \hline \text { Critical temperature } & 471 & 385 & 302 & 227 \\ \text { Critical pressure } & 43.5 & 40.6 & 38.2 & 37.0 \end{array} $$ (a) List the intermolecular forces that occur for each compound. (b) Predict the order of increasing intermolecular attraction, from least to most, for this series of compounds. (c) Predict the critical temperature and pressure for \(\mathrm{CCl}_{4}\) based on the trends in this table. Look up the experimentally determined critical temperatures and pressures for \(\mathrm{CCl}_{4}\), using a source such as the CRC Handbook of Chemistry and Physics, and suggest a reason for any discrepancies.

All the given compounds are halogenated methanes. The general molecular formula of these compounds is: \(\mathrm{C}_{1}\mathrm{H}_{4-n}\mathrm{X}_{n}\); where n is the number of halogenating molecules, X represents the halogen atoms(Cl or F), and (4-n) represents the number of Hydrogen molecules. Since the given molecules contain polar bonds (C-F and C-Cl), they exhibit dipole-dipole interactions. In addition to this, all of these molecules contain elements with lone electron pairs leading to London dispersion forces (also called Van der Waals forces). In summary: - CCl3F has dipole-dipole interactions and London dispersion forces. - CCl2F2 has dipole-dipole interactions and London dispersion forces. - CClF3 has dipole-dipole interactions and London dispersion forces. - CF4 has dipole-dipole interactions and London dispersion forces. #b: Order of increasing intermolecular attraction#

The order of increasing intermolecular attraction will depend mostly on the strength of the dipole-dipole interactions, as London dispersion forces will be similar for these compounds. The strength of dipole-dipole interactions increases with an increasing number of polar C-Cl bonds. So, the order of increasing intermolecular attraction would be: CF4 < CClF3 < CCl2F2 < CCl3F. #c: Predicting critical temperature and pressure for CCl4#

To predict the critical temperature and pressure for CCl4, we will identify trends in the given data for other halogenated methanes: Compound Critical Temp (K) Critical Press (atm) CCl3F (One Cl replaced with F) 471 43.5 CCl2F2 (Two Cls replaced with Fs) 385 40.6 CClF3 (Three Cls replaced with Fs) 302 38.2 CF4 (All Cls replaced with Fs) 227 37.0 From the given data, we observe that: 1. As the number of F atoms increases and the number of Cl atoms decreases, the critical temperature decreases. 2. As the number of F atoms increases and the number of Cl atoms decreases, the critical pressure decreases slightly. 3. For CCl4, since all the Cl atoms are still present, we can expect its critical temperature and pressure to be higher than CCl3F. Hence, we can predict the critical temperature for CCl4 to be around 500K and critical pressure to be around 45 atm. To compare our prediction with experimental values, we can check a reliable source like the CRC Handbook of Chemistry and Physics. The experimentally determined values for CCl4 are: - Critical temperature: 556.4 K - Critical pressure: 45.6 atm

Our predicted values for critical temperature and pressure are close to the experimental values. However, there is some discrepancy, which could be attributed to various factors such as the oversimplification of our trend analysis, differences in molecular geometries, atomic interactions, and other factors that affect critical temperature and pressure, which were not taken into consideration.