freestylerhb6 - 21-10-2003 at 13:05
I'm a High School student taking AP chem. Recently, my teacher has been going over different net ionic equations with us. However, I like to
know more than just the net ionic equation, I like to know the full molecular equation. She couldn't help me with these equations though.
Question 1: Excess concentrated potassium hydroxide is added to a precipitate of zinc hydroxide.
Net ionic equation: OH-(aq) + Zn(OH)2(s) --> Zn(OH)4 2+(aq)
What is the full molecular equation?
Question 2: An acidified solution of sodium permanganate is added to a solution of sodium sulfite.
Net ionic equation: MnO4 -(aq) + SO3 2-(aq) --> Mn2+(aq) + SO4 2-(aq)
What is the full molecular equation?
Question 3: Carbon dioxide gas is bubbled through water containing a suspension of calcium carbonate.
Net ionic equation: CO2(g) + CaCO3(s) --> Ca2+(aq) + HCO3 -(aq)
What is the full molecular equation?
Thanks for any help that you can give me.
[Edited on 21-10-2003 by freestylerhb6]
vulture - 21-10-2003 at 13:10
1. 2NaOH + Zn(OH)<sub>2</sub> --> Zn(OH)<sub>4</sub><sup>2-</sup> +
2Na<sup>+</sup>
Notice that the charge of your zinc complex was wrong.
The OH- can also be delivered by a base like NH3:
NH<sub>3</sub> + H<sub>2</sub>O --->NH<sub>4</sub><sup>+</sup> + OH<sup>-</sup>
Won't get the rest done before I go to sleep...anybody care to fill in?
BTW, it's great to see a new member that actually wants to go indepth on his/her chemistry homework.
Usually we have to solve them without the poster giving a fuck about chemistry.
Welcome! 
[Edited on 21-10-2003 by vulture]
BromicAcid - 21-10-2003 at 15:33
Question 3: Carbon dioxide gas is bubbled through water containing a suspension of calcium carbonate.
CO2(g) + CaCO3(s) --> Ca2+(aq) + HCO3 -(aq)
That is the molecular equation, the in between step is the formation of unstable carbonic acid H2CO3 by the carbon dioxide acting on the water, so I
guess it would be:
H2CO3(aq) + CaCO3(s) ---> Ca(HCO3)2(aq)
or
H+(aq) + HCO3-(aq) + CaCO3(s) ---> Ca2+(aq) + 2HCO3-(aq)
(Carbonic acid is a weak acid so usually the equilibrium only allows for one of the hydrogens to ionized, the equilibrium constant for the second one
is really low)
One more thing, for the Mn2+, if that forms then usually the acid name is necessary because it will contain the anion to balance the charge, although
with permanganate and acid it could also form the dioxide but that isn't what you asked.
[Edited on 21-10-2003 by BromicAcid]
freestylerhb6 - 21-10-2003 at 18:34
Is it possible to just have H+ ions in solution and there not be an anion? If so, what is the Mn2+ paired with in solution. I understand that if HCl
had been ionized that Mn2+ would have Cl- as an anion to pair with. But if no anion is present what is the Mn2+ paired with, if anything? This goes
back to my "Question #2" b/c you got me to thinking about the anion and I think thats why I'm confused. So that is the reason I'm
having trouble b/c if the anion isn't given to you, I don't understand what is left in solution for the Mn2+ to pair with. Thank you
everyone. This is helping me more than you could imagine.
another equation
freestylerhb6 - 22-10-2003 at 04:46
Hey. I just wanted to let you guys know that the questions though ignorant in your eyes have nothing to do with my class. It is just that I have a
dimwitted teacher who can't answer my questions. So I generally seek the answers out online. This is my last resort when I can't find them
online. I know that you guys get irritated when people have obvious homework questions that they ask you and expect easy answers. Please know that
my questions are for my own pursuit of enlightening, not my quick grade in a class. Anyway, with that being said can anyone explain to me this....
A strip of copper is immersed in dilute nitric acid.
My teacher said the net ionic equation was...
Cu(s) + H+(aq) +NO3 -(aq) --> Cu 2+(aq) + H2O(l) + NO(g)
I don't understand how this is right. If it is wrong will you please correct it. If it is right, will someone give me a quick explanation as to
why it is correct. Finally, as with my previous post, I'd like to know the full molecular equation for this reaction.
I greatly appreciate the help you guys.
ziqquratu - 22-10-2003 at 05:15
Your equation is unbalanced.
What I get is:
3Cu(s) + 8H+(aq) + 2NO3-(aq) --> 3Cu2+(aq) + 4H2O(l) + 2NO(g)
The extra H's come from other acid molecules - what happens in this reaction is some of the nitric acid goes towards oxidizing the copper to
cupric ions, while other acid molecules provide H+ and form cupric nitrate. The full equation would be:
3Cu(s) + 8HNO3(aq) --> 3Cu(NO3)2(aq) + 4H2O(l) + 2NO(g).
(you can turn that into ions if you want... pretty simple)
By the way, this may seem ignorant, and I DID check out the FAQ, but how does one sub/superscript letters, numbers etc. on this board? Is it
possible?
Subscript
Mephisto - 22-10-2003 at 06:25
Unfortunately you can’t find this in the FAQ, but it’s possible. Here we go:
Text here Use < and > instead of [ and ]. I used [ and ] just to show it.
Example: H<sub>2</sub>O
Hope I could help. I never seen superscript here.
vulture - 22-10-2003 at 08:11
No, there always must be counterions,whether there are cations or anions present. All ions come from a starting material, be it a salt or an acid.
MnCl2 isn't possible in this case, since HCl can't act as a H+ source here, because it is oxidized to Cl2 and H2O by MnO4-.
Merged the threads...
[Edited on 22-10-2003 by vulture]
blip - 22-10-2003 at 12:39
I have a few links in my signature, one of them is basic HTML formatting for everyone on the board. The other right now is a long, but very interesting story.
Btw freestylerhb6, H<sup>+</sup> ions really exist in solution as H<sub>3</sub>O<sup>+</sup> ions because a proton
(aka hydrogen ion) coordinately covalently bonds to a water molecule not unlike the formation of ammonium ions
(NH<sub>4</sub><sup>+</sup>
. While browsing around, I
found a great chemguide <a href="http://www.chemguide.co.uk/index.html" target="_blank">here</a> that I suspect would
be perfect for you. Its not particularly boring or tedious to read; I think I was able to keep it up for 6+ hours.
Superscript
Mumbles - 22-10-2003 at 14:02
Superscript is the same basic way subscript is done only with sup instead of sub. Its looks like this: <xmp> <sup>The text</sup>
</xmp>
btw, to show the actual html code, (I know you're wondering) you have to add <xmp><xmp>the html code<
/xmp></xmp></xmp>
Just delete the space between the < and / in the last one. I couldn't get it to show up without that.
H<sup>+</sup><sub>aq</sub> + Cl<sup>-</sup><sub>aq</sub> ---> HCl<sub>aq</sub>
JustMe - 23-10-2003 at 15:47
freestylerhb6
Hm, if I understand your issues regarding question two... well, the anion paired with the Mn+2 is Sulfate (SO4-2). I'm guessing that it seems
confusing because your question concerns two anions, and you wind up with a cation and an anion. A better way to look at it is as a redox reaction. In
MnO4-, Mn is in the +7 oxidation state, and in SO3-2, (sulfite), the Sulfur is +4. While oxidizing Sulfur to +6 in Sulfate, the Mn is reduced from +7
to +2. In general you will have other nonparticipating ions such as K+, and others that may participate (like OH- or H3O+) in similar reactions.
Oxygen often winds up in neutral water. But the charges of the anions and cations will always balance out in the end.
Hope this helps some, I wasn't sure what you were trying to understand about the reaction. The actual reaction stoichiometry is easily found in
many chemistry books.
Thanks JustMe
freestylerhb6 - 24-10-2003 at 04:52
Yea that is what I was having trouble with on number 2. However, I have one more question is there water formed or not? I don't understand
where all the oxygen is going. It doesn't all oxidize the Sulfur does it? I have no problem understanding the net ionic equation, but the full
molecular equation is. That probably sounds absurd but thats just my understanding of this stuff.