6 markers Flashcards
1
Q
The solubility of two compounds in different solvents was investigated. A summary of the findings is shown.
2-methylpentane not soluble in water but soluble in hexane
potassium bromide soluble in water but not soluble in hexane
Explain the findings of the investigation by considering the interactions between the compounds and each of the solvents.
A
- 2-methylpentane is insoluble in water as it cannot hydrogen bond to water (as none of the hydrogen atoms are electropositive)
- 2-methylpentane is soluble in hexane as London forces in both compounds (are similar in strength / size)
- so (resultant) forces in mixture are similar in magnitude to those in each liquid
- potassium bromide is soluble in water as its ions are hydrated when dissolved
- the enthalpy change of hydration is greater than / close to / compensates for the energy needed to break apart the lattice
- potassium bromide is insoluble in hexane as any (London) forces that form between it and hexane would be smaller in magnitude than the forces between the ions
