writing equations Watch

JUSTME1
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#1
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#1
does any one no the best way to understand this and possible give me an example.

Thank You
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Eau
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#2
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You mean chemical equations?? I think wikipedia would be a really good place for this kind of broad topic...

http://en.wikipedia.org/wiki/Chemical_equation
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JUSTME1
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im realy getting upset to why i cant understand this.

I get this
heating magnesium and sulphur powders together produces solid magnesium sulphide.

Mg(s) + S(s) = MgS(s


but not this
calcium carbonate breaks down on heating to give calcium oxide and carbon dioxide.

CaCO3(s) = CaO(s) + CO2(g)


how do u got three oxygens in calcium carbonate, how is it worked out


any help is much appreciated as this is really stressing me out now.

How do u work them out? Is there a simple way?

Thank You
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JUSTME1
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#4
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#4
can any one help plz
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generalebriety
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(Original post by JUSTME1)
im realy getting upset to why i cant understand this.

I get this
heating magnesium and sulphur powders together produces solid magnesium sulphide.

Mg(s) + S(s) = MgS(s


but not this
calcium carbonate breaks down on heating to give calcium oxide and carbon dioxide.

CaCO3(s) = CaO(s) + CO2(g)


how do u got three oxygens in calcium carbonate, how is it worked out


any help is much appreciated as this is really stressing me out now.

How do u work them out? Is there a simple way?

Thank You
What level are you at?

The carbonate ion is always CO32-. And the sulphide ion is always S2-.
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JUSTME1
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#6
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radical symbols such as

Symbol Ion
Ammonium NH4
Hydroxide OH
Nitrate NO3
Bicarbonate HCO3
Bisulfite HSO3
Bisulfate HSO4
Carbonate CO3
Sulfite SO3
Sulfate SO4
Phosphate PO4


Do they have to be memorised or is there a way to work them out.

Are there any other radical symbols.

plz can anyone help me understand this
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Eau
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(Original post by JUSTME1)
radical symbols such as

Symbol Ion
Ammonium NH4
Hydroxide OH
Nitrate NO3
Bicarbonate HCO3
Bisulfite HSO3
Bisulfate HSO4
Carbonate CO3
Sulfite SO3
Sulfate SO4
Phosphate PO4


Do they have to be memorised or is there a way to work them out.

Are there any other radical symbols.

plz can anyone help me understand this
These ions are like so as they are usually most stable that way. Why that is so cannot be explained easily (quantum mechanics, or at more simple level, perhaps Lewis structures/octet rule).

I suggest you memorise them, if required. By the way, you missing the ions' charges for the above list...
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JUSTME1
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How Do I Work The Ion Charges Out Or Do They Have To Be Memorised
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generalebriety
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(Original post by JUSTME1)
How Do I Work The Ion Charges Out Or Do They Have To Be Memorised
You still haven't answered my question. What level are you at?
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JUSTME1
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im talking about gcse level
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iceman_jondoe
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at gcse you dont have to understand it just learn it. Its not that hard, theres not that many equations you need to learn at gcse anyway
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generalebriety
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Yep. Learn 'em.
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henryt
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#13
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Let's see...

Symbol
Ammonium NH4 +
Hydroxide OH -
Nitrate NO3 -
Bicarbonate HCO3 -
Bisulfite HSO3 -
Bisulfate HSO4 -
Carbonate CO3 2-
Sulfite SO3 2-
Sulfate SO4 2-
Phosphate PO4 3-

Better? Hm. I'm so glad I never have to do Chemistry again
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MeAndBubbles
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I suggest learning the Periodic Table and about valencency. It's interesting stuff, and you don't have to just memorise parrot fashion as was intimated above.

It was bad teaching that led me to drop Chemistry at 14 years old. I'd try not to avoid understanding and on the contrary someone at gcse should be fascinated by the subject and wanting to understand it. But yeh, it's fascinating that the element can be arranged in groups and periods, but yeh, the reason for that would be beyond your level, but not the stuff about ions.
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generalebriety
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(Original post by well_tempered)
I suggest learning the Periodic Table and about valencency. It's interesting stuff, and you don't have to just memorise parrot fashion as was intimated above.

It was bad teaching that led me to drop Chemistry at 14 years old.
You reckon people should learn about valency at 14? I don't even know about that crap, and I did AS chemistry. Of course, it's needed to work all these ions out, but it's A2 or beyond. And not without reason.

And to be honest, groups and periods are nothing more than s, p, d and f subshells, which could be explained in under 50 words. I think you've got things the wrong way round.
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JUSTME1
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#16
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Well my situation is that its been 2 years since I have done my gcse's because of this I have forgot a few things. I never realy paid attention to
chemcial equations in my GCSE,now that i want to do my A-levels in sciences I am revisng over some material. I want to make sure I know everything up to GCSE level so that when I start I am ready for my AS year
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MeAndBubbles
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(Original post by generalebriety)
You reckon people should learn about valency at 14? I don't even know about that crap, and I did AS chemistry. Of course, it's needed to work all these ions out, but it's A2 or beyond. And not without reason.

And to be honest, groups and periods are nothing more than s, p, d and f subshells, which could be explained in under 50 words. I think you've got things the wrong way round.

What are you talking about? This is sooo easy, and would fasciliate his learning or memorising those ionic equations. For example, Sodium Hydroxide, you got the sodium ion in group 1, and group 1 have valency of 1, therefore the hydroxide anion must have the same negative change of 1...

Don't you think? Definitely in my O'level book.
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generalebriety
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(Original post by well_tempered)
What are you talking about? This is sooo easy, and would fasciliate his learning or memorising those ionic equations. For example, Sodium Hydroxide, you got the sodium ion in group 1, and group 1 have valency of 1, therefore the hydroxide anion must have the same negative change of 1...

Don't you think? Definitely in my O'level book.
That's not too bad until you get to 'ambiguous' compounds like iron oxide, which could be Fe2O3 or FeO, because the transition metals are weird. And this all assumes sodium hydroxide exists (ok, I'm a mathematician, not a chemist, but you see my point :p:), and has formula NaOH (rather than Na2OH or Na(OH)2 or something). But then, of course, to work out that it's NaOH, you have to know in advance that the hydroxide anion has a charge of -1, and I'd call that circular reasoning.

I mean, I could do exactly the same as you've just done with magnesium hydroxide. All I need to do is claim the formula is MgOH - which of course it isn't - and that "proves" that the OH ion has a 2- charge. You'll tell me I'm being stupid because the formula is Mg(OH)2, but can you prove that without knowing in advance that the OH ion has a 1- charge? I certainly can't. And then - if my very hazy memory serves me correctly - we have to start messing around with lone pairs and bonding pairs and all sorts of stuff that's complicated and washy even at A-level.
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MeAndBubbles
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I see, well I see your going off at a tangent,

The metal Magnesium, groups 2, valency therefore 2, so the hydroxide anions will be -2. Yes or No?

I know the transition metal Fe has several valencies, was this your point you were cautioning me on?
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Bezzler
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No!

Hydroxide anion is a valency -1

That you just have to learn, to try and understand it is beyond GCSE level. At GCSE you aren't expected to be able to work out the polyatomic ionic charges, although the monatomic ones are relatively simple to do from the periodic table (basically add or subtract the group from 8 - a bit simplistic but that's roughly it). You have to learn polyatomic ones for GCSE though.

Because in a compound the charge has to be neutral for it to be stable you therefore have Mg(OH)2 (little 2), as this is Mg 2+ + 2OH- which makes a neutral compound.

Similarly in a balanced equation not only do the number of each type of atom have to be equal but the charge has to be equal on both sides; this is important in oxidation and reduction.
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