neutraliztion

[Primarygun]

In the reaction between calcium hydroxide and sulphuric acid, the concentration of each one plays an important role to the formation of salt.

If you don't want to have acid salt as the product as it lowers the pH value, what's the ratio of H2SO4 to Ca(OH)2 do you choose? 1:2? or 1:1?

[fermions]

theoratically I think it's 1:1 but at the same time insolubel CaSO4 will be formed that may left some Ca(OH)2 unreacted...

[budullewraagh]

Cu(OH)2 is really insoluble. like. you could put, say, 100g in 100mL water and you'd get a very small fraction of a gram to dissolve. moreover, the pH would be like 7.000005

[Primarygun]

How about calcium hydroxide solution?

[budullewraagh]

calcium hydroxide solution would be incredibly dilute. consequently, the pH will be ever so slightly above 7, but hardly alkaline. for all intents and purposes, alkaline earth hydroxides are only effective as alkalines when they are added to acidic solutions.

[Primarygun]

1:1 ?

[budullewraagh]

what?

[Primarygun]

In the reaction between calcium hydroxide and sulphuric acid, the concentration of each one plays an important role to the formation of salt.

If you don't want to have acid salt as the product as it lowers the pH value, what's the ratio of H2SO4 to Ca(OH)2 do you choose? 1:2? or 1:1?

After considering the factors, I change the calcium hydroxide into calcium hydroxide solution.

[budullewraagh]

you can't have calcium hydroxide solution. it's almost completely insoluble. however, if you have sulfuric acid and add solid calcium hydroxide, an acid base reaction will occur.

 

if you do the reaction in a 1:1 ratio, you should get an equilibrium with primarily CaSO4 and H2O. if you do it in a 1:2 ratio of calcium hydroxide to sulfuric acid, you should get Ca(HSO4)2 and H2O

[Primarygun]

How about 1:3?

[budullewraagh]

then you have an excess of sulfuric acid with your bisulfate

[Primarygun]

Not excess calcium hydroxide?

[budullewraagh]

if you have 3 parts H2SO4 for every 1 part Ca(OH)2 then you have the bisulfate, water and an excess of sulfuric acid

[jdurg]

Are you sure about that? Ca(OH)2 is considered a strong base and H2SO4 is a strong acid, so I think you'd be more likely to see the complete neutralization to CaSO4 and 2H2O.

[budullewraagh]

it depends on the concentrations. sulfuric is a strong acid, but the second hydronium cation's dissociation constant is a bit high. if you had 2 parts sulfuric per calcium hydroxide, you'd get the bisulfate. if you did it 1:1 you'd get calcium sulfate, and it would probably go to completion

[jdurg]

That still doesn't make sense. You're saying that if the calcium hydroxide and sulfuric acid are in equal concentrations, that it will form water and calcium sulfate. But if you have an amount of sulfuric acid that exceeds the amount of calcium hydroxide, the calcium hydroxide will no longer be a strong base and will fail to neutralize the sulfuric acid. I find that very hard to believe. Calcium hydroxide is a strong base so it has no problem neutralizing a weak acid. Saying that it can't neutralize the weak acid just doesn't make sense. That's like saying that sodium hydroxide is unable to neutralize formic acid because formic acid has a small Ka.

[jdurg]

Here's another thing. Think about the bisulfate ion in an acidic solution. That's analagous to the bicarbonate ion in an acidic solution. It just does not want to exist. It will break down and form sulfur dioxide and water.

[budullewraagh]

"That still doesn't make sense. You're saying that if the calcium hydroxide and sulfuric acid are in equal concentrations, that it will form water and calcium sulfate. But if you have an amount of sulfuric acid that exceeds the amount of calcium hydroxide, the calcium hydroxide will no longer be a strong base and will fail to neutralize the sulfuric acid. I find that very hard to believe. Calcium hydroxide is a strong base so it has no problem neutralizing a weak acid. Saying that it can't neutralize the weak acid just doesn't make sense. That's like saying that sodium hydroxide is unable to neutralize formic acid because formic acid has a small Ka."

you arent following me at all. think of it. if there is an excess of sulfuric acid, there will be some bisulfate formed. if there is a 2:1 ratio, there will be no sulfate and all bisulfate. consider:

 

1 mole of Ca(OH)2

1 mole of H2SO4

you get 1 mole of CaSO4

 

1 mole of Ca(OH)2

1.5 moles of H2SO4

according to your theory we would end up with 0.5 moles of H2SO4, unreacted, with 1 mole of CaSO4. the H2SO4 reacts with CaSO4 to form Ca(HSO4)2

 

do you follow?

[budullewraagh]

oh and with regard to your last post. theoretically then, you could add one calcium atom to a solution of bisulfate and it would all decompose over time, right?

[jdurg]

But the calcium ion is neither acidic nor basic. That's like saying that sodium chloride is acidic.

[budullewraagh]

a calcium atom when added to water becomes basic, as the hydroxide is formed

[jdurg]

That's calcium metal. If you seriously believe that calcium chloride is a basic salt, you need to check your sources again.

[budullewraagh]

ok, what's a calcium atom then? i said calcium atom in the first place, referring to the pure element which happens to be a metal. and no, of course i dont think calcium chloride is a basic salt. who mentioned chloride anions?

[jdurg]

But ya see, I can easily add calcium atoms to a solution of water by adding in calcium chloride, or calcium nitrate, or any other calcium salt. I guess this is why it's so VERY important to be specific in what you're describing. If you say elemental calcium, then I fully agree that it forms a basic solution upon addition to water. But just saying a 'calcium atom' can mean many things. (Because Ca+2 is just as much a calcium atom as Ca itself is).

[budullewraagh]

no, the chloride and nitrate would be calcium cations. you'd be vague if you were calling them calcium atoms.