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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
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 Ptotal, `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 |
| 36.0 | 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 |
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