hi, pls could i have some help on this question? I know that K3 is the largest but I thought K2 would be larger than K1 because AgI bond is weaker than AgCl so it would dissociate a bit more so there will be more products and therefore Kc would be larger by a small amount? Here is the question: https://ibb.co/5Ws2rb7 thanks!
hi, pls could i have some help on this question? I know that K3 is the largest but I thought K2 would be larger than K1 because AgI bond is weaker than AgCl so it would dissociate a bit more so there will be more products and therefore Kc would be larger by a small amount? Here is the question: https://ibb.co/5Ws2rb7 thanks!
The level of my proposal is very simple. But it is correct.
==>Silver Chloride (AgCl): low dissociation in water.(Off-topic: also have in mind the solubility constant Ksp). ==>Silver Iodide (AgI): dissociation lower than AgCl in water. (Off-topic: also have in mind the solubility constant Ksp). This means tha K1 and K2 are small numbers. ==>Ag^+ reacts with NH3, they form a stable complex: Ag(NH2)2^+. This means the reaction is spontaneous (happens easily), and K3 is big.
Answer: K3 (big) > K1 (small) > K2 (very small) So, the answer is C.
Ciao, Sandro
My signature:"Regardless of where you may be, expressing gratitude is a universally cherished gesture."
hi, pls could i have some help on this question? I know that K3 is the largest but I thought K2 would be larger than K1 because AgI bond is weaker than AgCl so it would dissociate a bit more so there will be more products and therefore Kc would be larger by a small amount? Here is the question: https://ibb.co/5Ws2rb7 thanks!
As above, the indication that AgCl dissolves in ammonia whereas AgI does not suggests that AgCl is more readily ionised than AgI and so is unexpectedly more soluble. The rest of their answer, however, contains several errors.
For starters, Cl^- does not H-bond to water. It is not sufficiently charge dense, despite how electronegative Cl is and so it is better to describe the interactions as “ion-dipole interactions”.
HI will never form by dissolving an iodide salt in water or even ammonia solution. The reactions required for that to be the case simply make zero sense when you think about them (i.e they would be weak acid + weak base —> strong acid + strong base, which is practically impossible).
I think a better way to phrase the explanation would be “since Cl^- is more charge-dense, it is more readily solvated than I^- and so is more likely to form the ion-dipole interactions that help it to stay in solution. As a result, AgCl is more soluble in water”.
The level of my proposal is very simple. But it is correct.
==>Silver Chloride (AgCl): low dissociation in water.(Off-topic: also have in mind the solubility constant Ksp). ==>Silver Iodide (AgI): dissociation less than AgCl in water. (Off-topic: also have in mind the solubility constant Ksp). This means tha K1 and K2 are small numbers. ==>Ag^+ reacts with NH3, they form a stable complex: Ag(NH2)2^+. This means the reaction is spontaneous (happens easily), and K3 is big.
Answer: K3 (big) > K1 (small) > K2 (very small) So, the answer is C.
Ciao, Sandro
My signature:"Regardless of where you may be, expressing gratitude is a universally cherished gesture."
Just to clarify my post, this is correct (I was correcting the post above it), but the answer could be improved by identifying what indicates that AgCl should dissolve more easily than AgI since the OP’s confusion seems to arise from this area.
As above, the indication that AgCl dissolves in ammonia whereas AgI does not suggests that AgCl is more readily ionised than AgI and so is unexpectedly more soluble. The rest of their answer, however, contains several errors. For starters, Cl^- does not H-bond to water. It is not sufficiently charge dense, despite how electronegative Cl is to form H-bonds and so it is better to describe the interactions as “ion-dipole interactions”. HI will never form by dissolving an iodide salt in water or even ammonia solution. The reactions required for that to be the case simply make zero sense when you think about them (i.e they would be weak acid + weak base —> strong acid + strong base, which is practically impossible). I think a better way to phrase the explanation would be “since Cl^- is more charge-dense, it is more readily solvated than I^- and so is more likely to form the ion-dipole interactions that help it to stay in solution. As a result, AgCl is more soluble in water”.
Sorry, is the reason cl- more charge sense because it has a smaller ionic radius? Therefore it will form stronger ion- dipole interactions with water and dissolve more than AgI? Is solubility based on the strength of of ion dipole bonds formed with water? Thanks
Sorry, is the reason cl- more charge sense because it has a smaller ionic radius? Therefore it will form stronger ion- dipole interactions with water and dissolve more than AgI? Is solubility based on the strength of of ion dipole bonds formed with water? Thanks
Spot on. Solubility is vastly improved if the ions are able to hydrate more easily as this prevents the ionic bond re-forming.
The following is what I would like to add: AgCl is more soluble than AgI due to a number of factors, including lower lattice energy, smaller ionic radius, higher electronegativity and the ability to form hydrogen bonds.
The following is what I would like to add: AgCl is more soluble than AgI due to a number of factors, including lower lattice energy, smaller ionic radius, higher electronegativity and the ability to form hydrogen bonds.
The following is what I would like to add: AgCl is more soluble than AgI due to a number of factors, including lower lattice energy, smaller ionic radius, higher electronegativity and the ability to form hydrogen bonds.
The lattice energies are actually pretty similar. As one might expect, AgCl has the more endothermic lattice dissociation energy (+905 kJ/mol vs +889 kJ/mol, according to the old A level data booklet issued by Edexcel).
The hydration enthalpies (which can be said to depend on electronegativity to some extent and also the ionic radii) are pretty different, however (-378 kJ/mol for Cl^- and -308 kJ/mol for I^-, according to WiredChemist).
If we also consider the hydration enthalpy of Ag^+ (-473 kJ/mol according to WiredChemist), the solution enthalpies of AgCl and AgI are +54 kJ/mol and +108 kJ/mol, respectively. That is to say that neither dissolve exothermically (and so there is little thermodynamic driving force for dissolving either salt) but AgI has a harder time dissolving as it has a more endothermic enthalpy change of solution.
I have previously explained that hydrogen bonding isn’t really useful to consider, as neither Cl^- nor I^- can form hydrogen bonds. It’s technically ion-dipole interactions, but it’s clear the general principle that Cl^- interacts more strongly with water due to it being more charge-dense seems to be understood.