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A2 chemistry atomisation question

18

hello, i've just started my A2's. For my hwk part of the question is the atomisation of sulphur (product: CaS solid), will the state of the sulphur be a gas?

cheers

Reply 1

charco

Study Forum Helper

18

gordon2002

hello, i've just started my A2's. For my hwk part of the question is the atomisation of sulphur (product: CaS solid), will the state of the sulphur be a gas?

cheers

atomisation (enthalpy) means making 1 mole of gaseous atoms

If you're making them from halgens then its

1/2Cl2(g) --> Cl(g)

from metals then

Na(s) --> Na(g)

Sulphur is usually considered to be a single structure i.e

S(s) --> S(g)

even though in reality it's

1/8S8(s) --> S(g)

[do not use this latter one]

Reply 2

Mustard-man

OP

18

O no sorry, I meant before it is atomised.

Reply 3

Mustard-man

OP

18

So before neutalisation to CaS, they are separate, ie Ca ion and S ion, at this stage the S ion would be gas wouldn't it?

Sorry for the earlier confusion

Reply 4

junners

Before the sulphur is atomised, it will be a solid.

Therefore you have to convert one mole of solid sulphur atoms to one mole of gaseous sulphur atoms (the atomisation enthalpy).

Once you have formed the gaseous sulphur atoms, then you now need to add an electron to each atom, to form one mole of gaseous ions (the electron affinity enthalpy).

Edited to say: It should then have a second electron affinity enthalpy as you need to add another electron to 1 mole of S^1- ions to form 1 mole of S^2- ions.

I assume you're talking about a Born-Haber cycle, right?

What does the neutralisation have to do with anything?

Reply 5

AnimalLover

junners

Before the sulphur is atomised, it will be a solid.

Therefore you have to convert one mole of solid sulphur atoms to one mole of gaseous sulphur atoms (the atomisation enthalpy).

Once you have formed the gaseous sulphur atoms, then you now need to add an electron to each atom, to form one mole of gaseous ions (the electron affinity enthalpy).

I assume you're talking about a Born-Haber cycle, right?

What does the neutralisation have to do with anything?

What he says ^^.

Also if you decompose CaS, it will be given off as a gas straight away. When it's atomised, it will turn into gaseous form after going through liquid form. It will form SO(2) gas (with adeqquate oxygen supply).

Enthalpy of atomisation, then first electron affinity, all of that multiplyed by two, then atomisation of calcium, then first two ionisation energies. The cycle isn't too bad.

Have you gone through thermal decomposition yet?

Reply 6

charco

Study Forum Helper

18

Man this thread is all over the place - everybody's talkin bout summat different!

Ask a proper question and you might get a proper reply...

Reply 7

AnimalLover

charco

Man this thread is all over the place - everybody's talkin bout summat different!

Ask a proper question and you might get a proper reply...

I do agree here. The question was poorly worded.

Reply 8

Mustard-man

OP

18

sorry, neutralisation had nothing to do with it. I got 2 different questions completely messed up. I'm alrite with the answer now, all I wanted to know was if the S is a solid :rolleyes:

Reply 9

Mustard-man

OP

18

AnimalLover

I do agree here. The question was poorly worded.

thank you for being so observant!

A2 chemistry atomisation question

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