Solubility

[iwilliwill]

Fe(OH)3 is a strong base, but it has low solubility..what does that say about its pH? does it mean that very small amount can be dissovled in water, but the part that does dissovle is 100% ionized? If so..is the resulting solution basic?

[jdurg]

Fe(OH)3 is a strong base, but it has low solubility..what does that say about its pH? does it mean that very small amount can be dissovled in water, but the part that does dissovle is 100% ionized? If so..is the resulting solution basic?

 

Yup. You've explained it perfectly. It's similar to Ca(OH)2, which is technically a strong base, but not very soluble.

[dttom]

Solubility is not something absolute, some of the Fe(OH)2 can be dissolved and result an alkaline solution as the present of OH-.

[Primarygun]

Ca(OH)2, which is technically a strong base

Whether calcium hydroxide is a strong base, this puzzles me a lot.

thanks.

[jdurg]

Ca(OH)2 is most definitely a strong base. The problem is that it is not very soluble at all. What little bit of Ca(OH)2 that does dissolve, however, completely dissociates into Ca+2 ions and 2OH- ions. Therefore, it is a strong base because it ionizes, for all intents and purposes, 100%. Solubility has NOTHING to do with whether or not a substance is a strong acid or a strong base. Only the % dissociation separates strong bases/acids from weak bases/acids.

[dttom]

And is there any difference between strong base and strong alkali?

[RyanJ]

And is there any difference between strong base and strong alkali?

 

Here is the best way I can think to put it.

 

All alkalis are bases, not all bases are alkalis - alkalis are bases that are soluable in water

 

So yes there is a difference and no there is not depending on what you are refering too.

 

Cheers,

 

Ryan Jones

[dttom]

yes, alkalis are soluble bases, then for example, calcium hydroxide, which is slightly soluble, then do we regard the soluble part of calcium hydroxide to be alkali, that mean do we regard calcium hydroxide as a strong alkali?

[RyanJ]

yes, alkalis are soluble bases, then for example, calcium hydroxide, which is slightly soluble, then do we regard the soluble part of calcium hydroxide to be alkali, that mean do we regard calcium hydroxide as a strong alkali?

 

Any alkali is a base too, Calcium Hydroxide is a strong alkali because it is soluable enough to make a decent alkali solution but its also a strong base because it can still neutralise acid in its non-solution form.

 

Make sence?

 

Cheers,

 

Ryan Jones

[dttom]

Any alkali is a base too' date=' Calcium Hydroxide is a strong alkali because it is soluable enough to make a decent alkali solution but its also a strong base because it can still neutralise acid in its non-solution form.

 

Make sence?

 

Cheers,

 

Ryan Jones[/quote']

Oh, a good answer for me, before, I believe calcium hydroxide is a strong alkali, and recently someone argue that it's a weak alkali, and I just want to have a comfirmation...

Anyway, thank you.

[RyanJ]

Oh' date=' a good answer for me, before, I believe calcium hydroxide is a strong alkali, and recently someone argue that it's a weak alkali, and I just want to have a comfirmation...

Anyway, thank you.[/quote']

 

I'm not shure if its strong enough to be considered a strong alkali but it is a strong base.

 

You may find your answer here: http://en.wikipedia.org/wiki/Calcium_hydroxide

 

Cheers,

 

Ryan Jones

[jdurg]

Actually, an alkali is another name for a base. Alkaline solution means a solution with a pH above 7. The reason for the name 'alkaline' meaning base is that early scientists and alchemists saw that any time a hydroxide or the pure metal of any Group 1 or Group 2 element dissolved in water, it created a basic solution. So pretty soon they started calling any basic solution 'alkaline'.

 

To be correct, the term 'alkaline' should never be used when doing research or making a lab report as it is not a proper way to describe a basic solution. Acidic and Basic are MUCH better than 'Sour' and 'Alkaline'.