Lithium and water

Eric's collar · 27 May 2011 at 15:52

If lithium is added to a trough of water, will it dissolve? I know that it forms lithium hydroxide but on the data leaflet it says only sodium, potassium and calcium hydroxides are the only hydroxides that are soluble in water.

Does this mean it will not dissolve in water?

WillyNelson · 27 May 2011 at 15:53

It 'burns' doesn't it...?

fieldy · 27 May 2011 at 15:54

I believe that means that it WILL?

V4NT0M · 27 May 2011 at 15:55

It reacts it does not dissolve.

Aod · 27 May 2011 at 15:55

the lithium reacts... energetically with the water, heating up extremely rapidly, as well as forming elemental hydrogen and lithium hydroxide. the elemental hydrogen usually combusts due to the heat of the reaction.

The lithium itself would form a salt on its own over time in water, but the hydrogen-fire accelerates this rapidly.

Video:

Tefal · 27 May 2011 at 15:56

Eric's collar said:
If lithium is added to a trough of water, will it dissolve? I know that it forms lithium hydroxide but on the data leaflet it says only sodium, potassium and calcium hydroxides are the only hydroxides that are soluble in water.

Does this mean it will not dissolve in water?

it reacts with the water and "fizzes" and moves rapidly across the surface.

So no.

It helps if you give us the exact question for your home work.

Usually when they're asking about what happenes with lithium and water they just want the fizzes and moves rapidly and producing hydrogen gas.

Eric's collar · 27 May 2011 at 15:59

I'll give the full question but it deviates slighty from what I'm asking and I can't remember it fully as it was in an exam.:

What is the difference between a reaction of sodium in water and lithium and explain why.

I initially thought, sodium is more reactive as it has a larger atomic radii therefore the reaction of sodium will be faster but for some reason I changed it to "lithium will not dissolve in water as lithium hydroxide is insoluble in water were as sodium hydroxide will dissolve as it is soluble in water"

Smithy0115 · 27 May 2011 at 16:15

It melts as it gets so hot.

Six7th · 27 May 2011 at 16:17

If it's solely asking for the difference between the reaction then I would have said with sodium it would be more violent and there would be more fizzing/hydrogen given off due to the reason you gave. Your other answer doesn't really answer the question.

Eric's collar · 27 May 2011 at 16:19

Six7th said:
If it's solely asking for the difference between the reaction then I would have said with sodium it would be more violent and there would be more fizzing/hydrogen given off due to the reason you gave. Your other answer doesn't really answer the question.

One dissolves, one doesn't. Is that not a difference?

Tefal · 27 May 2011 at 16:30

Eric's collar said:
I'll give the full question but it deviates slighty from what I'm asking and I can't remember it fully as it was in an exam.:

What is the difference between a reaction of sodium in water and lithium and explain why.

I initially thought, sodium is more reactive as it has a larger atomic radii therefore the reaction of sodium will be faster but for some reason I changed it to "lithium will not dissolve in water as lithium hydroxide is insoluble in water were as sodium hydroxide will dissolve as it is soluble in water"

oh in that case it's normally.

"the sodium reaction is more violent it moves about the surface of the water faster and produces a flame while the lithium is less vigorous and does not produce a flame"

then you can explain why if it's more than a 2 point question.

if this is gcse your first answer probably would have got you some points your later probably none.

Tefal · 27 May 2011 at 16:31

Eric's collar said:
One dissolves, one doesn't. Is that not a difference?

That's one of the products not the reaction.

Six7th · 27 May 2011 at 16:31

All group 1 hydroxides are strong bases (accept protons) and will fully dissociate into OH- and the metal cation in water so they should both dissolve. The hydroxide group will be negatively charged, so it should form ion-dipole bonds with the O atom of the water molecule. It might also be possible to form hydrogen bonds with the water due to the polarization of the O-H bond.

aardvark · 27 May 2011 at 16:47

sure its not as soluble as sodium hydroxide but lithium hydroxide is still pretty soluble in water.

Tefal · 27 May 2011 at 16:50

best advice i can give when they give you past papers in gcse/a level always get the marking schemes and read them well.

they'll show you exactly what they want for a specific wording, and will make sure you don't over think things.