[jsmith613]

I understand how to do displacement equations where the molecules reacting have 2 ions
e.g: K2CO3 + NaOH --> KOH + Na2CO3

However I do not know how to do displacement equations where one of the molecules reacting has 3 ions and the other one has 2
e.g: C6H8O7 + K2CO3 --> ??

OR where both molecules reacting have 3 ions
e.g: K2Cr2O7 + C6H8O7 --> ??

(I am not sure it equations 2 and 3 are valid but i hope you get the idea)

Please can someone explain to me how to do equations like 2 and 3

[cliverlong]

I understand how to do displacement equations where the molecules reacting have 2 ions
e.g: K2CO3 + NaOH --> KOH + Na2CO3

Do group 1 carbonates react with alkalis? I haven't come across this before.

Please use the subscript button on the editor. It makes the formulae much more readable e.g. K2CO3 becomes K₂CO₃ with little effort.

However I do not know how to do displacement equations where one of the molecules reacting has 3 ions and the other one has 2
e.g: C6H8O7 + K2CO3 --> ??

OR where both molecules reacting have 3 ions
e.g: K2Cr2O7 + C6H8O7 --> ??

(I am not sure it equations 2 and 3 are valid but i hope you get the idea)

Please can someone explain to me how to do equations like 2 and 3

I do not recognise C6H8O7 (or C₆H₈O₇). Being comprised of just carbon, hydrogen and oxygen the compound is going to be covalent not ionic.

First you need to find out the molecular formula for this compound. For example: methylamine: CH₃NH₂ gives some information about the bonding between the atoms whereas CNH₅ is pretty hopeless. The more atoms you get the more useless a simple listing of atoms with a single subscript becomes.

You need a more informative formula than : C₆H₈O₇. For the number of carbons it has a relatively high number of oxygens which need to bond to the carbons as either alcohol or carboxyl groups. Perhaps it is some kind of sugar? http://www.rpi.edu/dept/chem-eng/Biotech-Environ/FUNDAMNT/rings.htm
However, your formula is a bit "short" on hydrogens. I just don't recognise it - so it is difficult to determine if it has functional groups that will react with K₂CO₃ .

Clive

[Borek]

No idea what you mean by "have 3 ions".

[Arctic-Nation]

The weird oxygen compound is probably citric acid, and having 3 ions means tribasic. You not being able to figure out that last one disappoints me, Borek.

In cases where the ratio between the numbers of ionizable positions isn't unity, you just need to balance it out like in any other reaction. In case of K2CO3 + NaOH gives Na2CO3 + KOH, the balanced equation is K2CO3 + 2 NaOH gives Na2CO3 +2 KOH (note that this reaction isn't very likely to happen, but it'll do as an example). When you have a ratio of 3:2 as in the second example, the balanced equation is 2A + 3B gives 2C + 3D.

[jsmith613]

I understand how to do displacement equations where the molecules reacting have 2 ions
e.g: K2CO3 + NaOH --> KOH + Na2CO3
Do group 1 carbonates react with alkalis? I haven't come across this before.

As I said I was not sure if the equation was correct it was just a very bad example to pick

However I do not know how to do displacement equations where one of the molecules reacting has 3 ions and the other one has 2
e.g: C6H8O7 + K2CO3 --> ??

OR where both molecules reacting have 3 ions
e.g: K2Cr2O7 + C6H8O7 --> ??

(I am not sure it equations 2 and 3 are valid but i hope you get the idea)

Please can someone explain to me how to do equations like 2 and 3

I do not recognise C₆H₈O₇

First you need to find out the molecular formula for this compound.

C₆H₈O₇ is citric acid
http://en.wikipedia.org/wiki/Citric_acid
------------------------
but the point is, is there a specific method to do reactions where there are 3 ions per molecule.

[sjb]

C₆H₈O₇ is citric acid
http://en.wikipedia.org/wiki/Citric_acid
------------------------
but the point is, is there a specific method to do reactions where there are 3 ions per molecule.

Why could C₆H₈O₇ not be Isocitric acid? http://en.wikipedia.org/w/index.php?title=Isocitric_acid&oldid=294467125. But that's not important, in this case.

What I think you may need to do is see what parts of the chemicals are changing, and which are not. In some cases all 3 ions may undergo redox, in others fewer.

[jsmith613]

What I think you may need to do is see what parts of the chemicals are changing, and which are not. In some cases all 3 ions may undergo redox, in others fewer.

In other words do you want find the equation and then analyze the products to work out how the reactions work 

[Borek]

C₆H₈O₇ is citric acid

No, it is one of tens of compounds that have this formula. In the case of organic compounds it is structure that counts, just giving overall formula is ambiguous.

but the point is, is there a specific method to do reactions where there are 3 ions per molecule.

Still no idea what you mean by that. Citric acid dissociates to create four ions.

[jsmith613]

but the point is, is there a specific method to do reactions where there are 3 ions per molecule.

Still no idea what you mean by that. Citric acid dissociates to create four ions.

What I mean is, how can one work out the products in a reaction such as: C6H8O7 + K2CO3 --> ??

[Borek]

There is no specific method. You have to know what the substances are and how they can react. In this case you have an acid reacting with carbonate.

[jsmith613]

There is no specific method. You have to know what the substances are and how they can react. In this case you have an acid reacting with carbonate.

Yes but how do I know that name of the salt

[cliverlong]

C₆H₈O₇ is citric acid
http://en.wikipedia.org/wiki/Citric_acid
------------------------
but the point is, is there a specific method to do reactions where there are 3 ions per molecule.

Aha!

Can anyone confirm if an unambiguous and correct way to write the (condensed) structural formula for this compound is

CH₂COOHCOHCOOHCH₂COOH    ?

So (as already commented) you have an acid and are reacting this with a carbonate. Do you know any reactions of this type? Can you write an equation for the reaction? Big hint: compare the equations of the reaction of hydrochloric acid and sulphuric acid with metal carbonates.

Note, citric acid can exist as a crystalline solid or can dissolve in water. Will either of these affect citric acids reactivity with a carbonate?

What ions can citric acid form, under what conditions, and what reactions does this mean it can participate in? Have you studied acid dissociation constants for monoprotic and polyprotic acids?

Clive

[jsmith613]

Aha!

Can anyone confirm if an unambiguous and correct way to write the (condensed) structural formula for this compound is

CH₂COOHCOHCOOHCH₂COOH    ?

So (as already commented) you have an acid and are reacting this with a carbonate. Do you know any reactions of this type? Can you write an equation for the reaction? Big hint: compare the equations of the reaction of hydrochloric acid and sulphuric acid with metal carbonates.

Note, citric acid can exist as a crystalline solid or can dissolve in water. Will either of these affect citric acids reactivity with a carbonate?

Clive

Acid + Carbonate --> Salt + water + CO2 (what is the name of the salt)

What ions can citric acid form, under what conditions, and what reactions does this mean it can participate in? Have you studied acid dissociation constants for monoprotic and polyprotic acids?

I have not studied

[Borek]

No magic here:

citric acid -> citrate
acetic acid -> acetate
formic acid -> formate

sulfuric acid -> sulfate
nitric acid -> nitrate
phosphoric acid -> phosphate
carbonic acid -> carbonate

Doesn't mean it is always that simple, salt of hydrochloric acid is chloride...

[jsmith613]

No magic here:

citric acid -> citrate
acetic acid -> acetate
formic acid -> formate

sulfuric acid -> sulfate
nitric acid -> nitrate
phosphoric acid -> phosphate
carbonic acid -> carbonate

Doesn't mean it is always that simple, salt of hydrochloric acid is chloride...

OK so Potassium Carbonate + Citric acid --> Potassium Citrate + CO2 + Water
but thats not really what i care about, I am more interested as to how to determine the formula or Potassium Citrate
K2CO3 + C6H8O7 --> + CO2 + H2O