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Dan_Crew
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#1
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#1
Which Group 2 nitrate decomposes at the lowest temperature, and explain why?

I think it may be Berylium but i cant think why.

Anyone know?
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lgs98jonee
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#2
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Well at the top of the group 2, the ions formed are smaller but still have the same charge (+2) as those at the bottom. Due to berillyium's smaller size it has a higher charge density. This enables it to attract the electron cloud of the nitrate ion and distort it more. Thus it decomposes at a lower temperature than say barium nitrate. Hope this helps although I may have missed a bit out
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Dan_Crew
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#3
You seem to know a bit about group 2
Do u know why Mg sulphate is more soluble than Ba sulphate
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cobra
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#4
Same type of reason, smaller higher charge density higher up group
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Ralfskini
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(Original post by Dan_Crew)
You seem to know a bit about group 2
Do u know why Mg sulphate is more soluble than Ba sulphate

The solubility of group 2 sulphates depends on the lattice enthalpy and the hydration enthalpy of the resulting cation. The sulphate ion is large, and therefore changing the size of the cation has only a small effect on the lattice enthalpy, which is in part a function of the sum of the radii of the compound. Therefore, as the group is descended, there is only a small change in lattice enthalpy, but the decreasing charge density of the cations means that the hydration enthalpy yields more energy upon solvation. Because the solubility is favoured by compounds with high hydration enthalpies and low lattice enthalpies (the energy required to break the lattice is compensated for by the energy released from the formation of dative bonds from the water molecules), the solubility increases as the group is ascended because they group two sulphates will have similar lattice enthalpies, however the energy yielded by hydration of smaller group two cations means they are more soluble. There, Magnesium, which is smaller than Barium and has a higher charge density, will release more energy on hydration with water than the energy required to break the lattice and so is more soluble.


Ralfus.
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matouwah
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(Original post by Ralfskini)
The solubility of group 2 sulphates depends on the lattice enthalpy and the hydration enthalpy of the resulting cation. The sulphate ion is large, and therefore changing the size of the cation has only a small effect on the lattice enthalpy, which is in part a function of the sum of the radii of the compound. Therefore, as the group is descended, there is only a small change in lattice enthalpy, but the decreasing charge density of the cations means that the hydration enthalpy yields more energy upon solvation. Because the solubility is favoured by compounds with high hydration enthalpies and low lattice enthalpies (the energy required to break the lattice is compensated for by the energy released from the formation of dative bonds from the water molecules), the solubility increases as the group is ascended because they group two sulphates will have similar lattice enthalpies, however the energy yielded by hydration of smaller group two cations means they are more soluble. There, Magnesium, which is smaller than Barium and has a higher charge density, will release more energy on hydration with water than the energy required to break the lattice and so is more soluble.


Ralfus.
he is still doing AS....that will make no sense to him....
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