Asked by anonymous

Write formula equations and net ionic equations for the hydrolysis of the following salts in water.
a. sodium carbonate
b. ammonium bromide


I don't know what the products should be.
a. Na2CO3+H2O--> ?
b. NH4Br+H2O--> ?
Please help me with this. I really need this. Thanks in advance.
Answered by DrBob222
The hydrolysis of Na2CO3 ends us as the hydrolysis of the carbonate ion.
The molecular formula is
Na2CO3 + HOH==NaHCO3 + NaOH
NaHCO3 + HOH ==> H2CO3 + NaOH
The net ionic equations are
CO3^= + HOH ==> HCO3^- + OH^-
HCO3^- + HOH ==> H2CO3 + OH^-
but your teacher PROBABLY want you to show how you get from steps 1 and 2 to steps 3 and 4.

For NH4Br + HOH ==> NH3 + HBr
I'll let you make the change to the net ionic equation but I'll give you a hint. The Br^- is not hydrolyzed; the NH4^+ is hydrolyzed.
Answered by anonymous
I don't understand how you come up with this, are there any steps or rules in doing this?
Thanks.
Answered by DrBob222
For the NH4Br equation, do you understand the molecular equation I wrote. If so, I can give you the details on how we go from the molecular to the net ionic equation. The carbonate is tougher to explain on the boards like this.
Answered by anonymous
I don't get it....
Answered by DrBob222
OK.
Hydrolysis of NH4Br means just that. Hydrolysis means to react the compound with water. So we write
NH4Br + HOH ==> and do a double displacement reaction.
NH4Br + HOH ==> NH4OH + HBr.
We know that NH4OH doesn't exist, actually it's NH3 + H2O so let's write it that way.
NH4Br + HOH ==> NH3 + H2O + HBr
These are aqeous solution so we write them as ions. (This is changing the molecular equation into the ionic equation.)
NH4^+ + Br^- + HOH(l) ==> NH3(aq) + H2O(l) + H^+ + Br^-
The next step is to cancel ions common to both sides.
Immediately, I see a Br^- on each side so we cancel them.
NH4^+ + HOH ==> NH3 + H2O + H^+.
The H2O + H^+ combine to make the hydronium ion.
NH4^+ + HOH ==> NH3 + H3O^+
The last one is the net ionic equation.
Answered by anonymous
Can you explain that to me please?
Answered by anonymous
O thanks a lot :)
I think I got it!
Answered by anonymous
But I'm still confused with the sodium carbonate one
Answered by Goku
Why wouldn't NH4OH exist? Is it because the strength of the Hydroxide dominates the strength of the weak acid: NH4+?
Answered by fano
Na2CO3+H2O==HCO3+Na2O
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