Mangnesium oxide soluBility...?

[hassam]

why MgO is insoluble in water whereas NaCl is?

 

[Zishi]

why MgO is insoluble in water whereas NaCl is?

Remember that all compounds of 1st group are soluble in water...Mg and O are smaller ions (with greater charges) so their ionic bonds are stronger and harder to break.

 

[beacon_of_light]

MgO has greater lattice enthalpy but a lower hydration energy.
Thereby, strong ionic bonds b/w oppositely charged Mg2+ and O2- ions can't be broken easily.

A general rule:
If lattice enthalpy = hydration energy ... compound is partially soluble
If lattice enthalpy < hydration energy ...compound is soluble .
If lattice enthalpy > hydration energy... compound is insoluble.

 

[Zishi]

MgO has greater lattice enthalpy but a lower hydration energy.
Thereby, strong ionic bonds b/w oppositely charged Mg2+ and O2- ions can't be broken easily.

A general rule:
If lattice enthalpy = hydration energy ... compound is partially soluble
If lattice enthalpy < hydration energy ...compound is soluble .
If lattice enthalpy > hydration energy... compound is insoluble.

But isn't lattice enthalpy included in A2 syllabus? =s
I don't whether Hassam's question is asked in AS question papers or Not, but IF it is asked then still we'd have to tell about lattice enthalpy?

 

[beacon_of_light]

well solubility is part of A2... most of the questions are related to solubility of sulphates down the group. Maybe such type of questions won't be asked in paper 2 ...

 

[hassam]

oohh thnx guyx....