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Reply 200

FidoDiDo

Hey
Tricky Question :tongue:

Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.

Reply 201

Whywhywhy

FidoDiDo

Hey
Tricky Question :tongue:

Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.

They are polar so I say that short-chain ones are.

Reply 202

Whywhywhy

They are polar so I say that short-chain ones are.

Can anyone shed any light on this? I say that the trend follows that of alcohols (i.e., short-chain ones are soluble since the functional group is polar and the rest of the chain is small).

Reply 203

meawinner

misty

ANyone doing 3b edexcel chem exam on thursday???
if so, how r u revising, its a retake and when i took it the 1st time round we werent evn told we had it! heh

I use the syllabus and this philip allan book i have for that exam its ok. just know all the tests for ions and stuff and equations u learnt throughout the AS year. Also know all the calculation stuff coz that will definately come up.

Reply 204

misty

meawinner

hey- what do u mean the calculation stuff? do you mean like titrations, enthalpy calculations etc..?

Reply 205

etomac

when ionic stuff dissolve with water
does each ion form IONIC BONDS with water molecules?

Reply 206

john !!

FidoDiDo

Hey
Tricky Question :tongue:

Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.

Take a simple example, chloromethane - CH3Cl. The clorine is more electronegative than the carbon, so the electron shared pair will spend more time at the chlorine atom, giving that bond ionic charachteristics. This is not cancelled out because there is only one C-Cl bond, so the molecule has a dipole - the chlorine end is slightly negative and the end opposite the chlorine is slightly positive. This means that water, which is also polar, may be able to split it into Cl- and CH3+, but I'm not sure if this is the case - I think a molecuce needs to be beyond a critical amount of polarity before water can disolve them.

Reply 207

FidoDiDo

Whywhywhy

They are polar so I say that short-chain ones are.

Well that would be wrong :redface:

Reply 208

Whywhywhy

mik1a

Is that what I said?

Reply 209

A0307

etomac

when ionic stuff dissolve with water
does each ion form IONIC BONDS with water molecules?

The ions are hydrated - surrounded by the polar water molecules, the direction depends on the charge of the ion. I think it'll be an ionic bond but I'm not sure to be honest, I never thought of it like that.

Reply 210

FidoDiDo

etomac

when ionic stuff dissolve with water
does each ion form IONIC BONDS with water molecules?

Well the ions form Ion-dipole interactions with the H2O molecules..I thinks its H-bonds which is formed ..becuz u know for H-bonds .. hydrogen gets attracted to the lone pairs on another Atom.
As u know for H-bond to form
1- H must be attached to highly electronegative atom[Oxygen here]
2-Lone pairs should be present.. [ Cl-,the Oxygen atom in ethanol .. etc]

Reply 211

etomac

Q: Why do ionic compounds dissolve in polar solvent?
A: Because the polar solvent molecule break down the lattice

Is that right?

Reply 212

FidoDiDo

etomac

Q: Why do ionic compounds dissolve in polar solvent?
A: Because the polar solvent molecule break down the lattice

Is that right?

Yup

.. Becuz polar solvents are attracted to opposite ions in the Lattice

Reply 213

FidoDiDo

Returning for my question , the answer is

FidoDiDo

Hey
Tricky Question :tongue:

Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.

No .. they r immiscible becuz the C-Halogen bonds are not polar enough.

Reply 214

FidoDiDo

Hey i got this enthalpy question i want u guyz to check it up...
a) write equation between reaction of calcium with water.

b)When 1 g of calcium is placed in 200g of water, the temperature increases by 12.2 when the reaction is completed. The specific heat capacity of water c , is 4.2JGK
Calculate the heat releases in the experiment.

c)Calculate the standard enthalpy change of the reaction is KJMol for your equation in [a].

d) use Hess' law and your results in [c] to calculate the standard enthalpy of formation of Calciumhydroxide.You also need the standard enthalpy of formation of water which is -286KJmol.

e)calculate the volume of Hydrogen, measured at rtp, luberated in the expiremnt described in .

Reply 215

etomac

what should i say when the question ask

why does HCl dissolves in water?

Reply 216

FidoDiDo

etomac

what should i say when the question ask

why does HCl dissolves in water?

u should say becuz its a polar molecules and polar substances dissolve in polar solvents[ H2O here]

Reply 217

FidoDiDo

This is becuz .. HCL ---> H+ + Cl-
So the partial positive sides on the water molecules[H atom] will gather around the Chloride ion[ion-dipole interactions] and separate them from other ions.
And the partial negative sides on the water molecules[O atom] will gather around the Hydrogen ion[ion-dipole interactions] and separate them from othe ions.

Reply 218

etomac

ok thanks
if there are 2 marks to describe why metal conduct electricity should i write
-delocalised electrons
-free flow of electrons under the influence of a p.d.

Reply 219

FidoDiDo

etomac

ok thanks
if there are 2 marks to describe why metal conduct electricity should i write
-delocalised electrons
-free flow of electrons under the influence of a p.d.

Well i would say .. due to multiple atomic overlapping the outmost electrons get delocalised..becuz they are charged particles they act as charge carriers .. soo carry an electric charge throughout the metallic lattice ..which enables the metal to conduct electricity..