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प्रश्न
How is the sign of ΔmixH related to positive deviations from Raoult’s law?
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उत्तर
For solutions showing positive deviation from Raoult's law, `Delta H_"mixing" > 0`. This can be explained as follows:
More energy is needed to overcome A-A or B-B interaction forces than is released during the setup of A-B interaction forces during solution formation because the A-B molecular interaction forces are weaker than the A-A or B-B interaction forces. Heat is thus absorbed during the creation of such a solution, and the dissolution process is endothermic. For this reason, `Delta H_"mixing"` is advantageous in this instance.
संबंधित प्रश्न
Suggest the most important type of intermolecular attractive interaction in the following pair.
acetonitrile (CH3CN) and acetone (C3H6O)
Vapour pressure of pure acetone and chloroform at 328 K are 741.8 mm Hg and 632.8 mm Hg respectively. Assuming that they form ideal solution over the entire range of composition, plot `p_"total"`, `p_"chloroform"` and `p_"acetone"` as a function of `chi_"acetone"`. The experimental data observed for different compositions of mixtures is:
| `bb(100 xx chi_"acetone")` | `bb(P_"acetone"//"mm Hg")` | `bb(p_"chloroform"//"mm Hg")` |
| 0 | 0 | 632.8 |
| 11.8 | 54.9 | 548.1 |
| 23.4 | 110.1 | 469.4 |
| 36 | 202.4 | 359.7 |
| 50.8 | 322.7 | 257.7 |
| 58.2 | 405.9 | 193.6 |
| 64.5 | 454.1 | 161.2 |
| 72.1 | 521.1 | 120.7 |
Plot this data also on the same graph paper. Indicate whether it has a positive or negative deviation from the ideal solution.
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Suggest the most important type of intermolecular attractive interaction in the following pair.
Methanol and acetone
