I have a question about solubility of 2 chemicals?
The queston is
Many ionic compounds dissolve in water, but not all. Explain why NaCl is very soluble but CaO is only slightly souble.
any help would be greatly appreciated
Answer:
Its all to do with enthlapy and entropy.
Anything which is soluble usually has a negative standard enthlapy of solution - the energy involved when 1 mole of solute dissolves in a solvent to give an infinately dilute solution. However, NaCl has a slightly positive enthalpy of solution, yet it dissolves.
The reason for this is entropy - the change in the amount of disorder. When NaCl dissolves in solution, there is more chaos, more molecules within the solution. Any process that has a large positive entropy change will be favourable - spontaneous and can occur (reaction will 'go').
However, with CaO, the Ca2+ formed in solution has a high affinity (attraction to) for water molecules, hence a lot of water molecules are arranged orderly - less chaos and hence a negative entropy. This should in effect make the compound insoluble, however, the slight solubility is due to it still having a negative enthalpy change of solution - hence despite entropy it is still slightly soluble.
(You may be asking how is dissolving CaO possible if entropy is negative? The entropy of the system maybe negative, but the entropy of the surroundings is positive (dissolving gives out heat - exothermic), hence the overall entropy (sum of both entropies) is positive and the reaction will 'go'.
as nacl if react with water it will give naoh and hcl strong base and strong acid highly ionized and soluble in water while if cao react with water it will give calcium hydroxide which is not stonge base so it slightly soluble
More Questions and Answers:
What's the practical importance of having knowledge of reaction rates?
Addresses of analytical labs in bangalore city?
How many monochloro and monobromo isomers are there with 3-ethyl-4-methylhexane?
Balance the equation of H2SO4 + NH4OH--- (NH4)2SO4 + H2O?
What do you mean by salting-out effect??
Carbonyl compounds having fewer than four carbon atoms are very water soluble?
How do I make [NH3]=[NH4]=1, that is how would I make a solution in which the ammonia and ammonium concentrati
In what countries can you find gold, nickel, carbon, and uranium?
Organic compounds are always highly water soluble and flammable? True or false.?
Many ionic compounds dissolve in water, but not all. Explain why NaCl is very soluble but CaO is only slightly souble.
any help would be greatly appreciated
Answer:
Its all to do with enthlapy and entropy.
Anything which is soluble usually has a negative standard enthlapy of solution - the energy involved when 1 mole of solute dissolves in a solvent to give an infinately dilute solution. However, NaCl has a slightly positive enthalpy of solution, yet it dissolves.
The reason for this is entropy - the change in the amount of disorder. When NaCl dissolves in solution, there is more chaos, more molecules within the solution. Any process that has a large positive entropy change will be favourable - spontaneous and can occur (reaction will 'go').
However, with CaO, the Ca2+ formed in solution has a high affinity (attraction to) for water molecules, hence a lot of water molecules are arranged orderly - less chaos and hence a negative entropy. This should in effect make the compound insoluble, however, the slight solubility is due to it still having a negative enthalpy change of solution - hence despite entropy it is still slightly soluble.
(You may be asking how is dissolving CaO possible if entropy is negative? The entropy of the system maybe negative, but the entropy of the surroundings is positive (dissolving gives out heat - exothermic), hence the overall entropy (sum of both entropies) is positive and the reaction will 'go'.
as nacl if react with water it will give naoh and hcl strong base and strong acid highly ionized and soluble in water while if cao react with water it will give calcium hydroxide which is not stonge base so it slightly soluble
The answers post by the user, for information only, FunQA.com does not guarantee the right.
More Questions and Answers: