How do I balance net ionic equations for ionic compound reactions?

[amcavoy]

I need to write the NIE for these:

1. "0.1M lead nitrate, Pb\left(NO_3\right)_2 and 1.0M sodium chloride, NaCl."

2. "6M sodium hydroxide, NaOH, is added to 0.5M ammonium chloride, NH_4Cl."

For the first one, I set up the following equation (not balanced):

Pb\left(NO_3\right)_2+NaCl\rightarrow PbCl+NaNO_3

...however, I cannot seem to balance this. If I make it 2NaNO_3, then I have to do the same to NaCl on the other side, which in turn makes me have to do the same thing to Pb\left(NO_3\right)_2, and I keep going around in circles. Does anyone have a suggestion on this?

On the second problem, I set it up like this:

NaOH+NH_4Cl\rightarrow NaCl+NH_4OH

Would I be correct to say that NH_4OH isn't a strong electrolyte (because only NaOH, KOH, Ba(OH)₂, and Ca(OH)₂ are)? And as far as NH_4Cl goes, I cannot tell if it is a strong electrolyte or not. For this molecule, how would I determine this?

Thanks a lot for your help.

 

[mrjeffy321]

usually in a net ionic equation, there are ions (at least that's how I remember writting them out).

On the first equation,
lead starts out with a +2 charge, but then changes to a +1 on the product side. This is strange, since lead doesn't usually ever have a +1 charge, it likes +2 or +4. Not to mention, I think the propper formula for Lead Chloride is PbCl2, meaning that is does indeed carry the +2 charge all the way through the reaction. Are you sure it is suppose to be PbCl ?

In the second reaction, NaOH, NH4Cl, NaCl ad NH4OH are all very soluble and will break into ions in water.
I am not absolutely sure, but I don't think NH4OH is a string electrolyte, as it does not dissassociate nearly as much as other ionic compounds do, but I do know that NaOH and NaCl are strong electrolytes.

 

[amcavoy]

Thanks for the reply. I must have overlooked the charge. I figured those to out, but now on my last, I have this:

"Carbon dioxide is bubbled into an aqueous solution of 1.0M calcium hydroxide."

My equation is as follows:

CO_2+2Ca\left(OH\right)_2\rightarrow C\left(OH\right)_4+Ca_2O_2

...after doing the work out, I come up with this net ionic equation:

C^{+4}+4OH^{-}\rightarrow C\left(OH\right)_4

Did I do this correctly?

 

[scrappychic]

I am not sure if this helps, or is even steering you into the correct direction, but when you bubble CO2 into water, you usually get carbonic acid. Is it the carbonic acid or the CO2 that reacts with the calcium hydroxide? You might want to think about that, too.

 

[Gokul43201]

"Carbon dioxide is bubbled into an aqueous solution of 1.0M calcium hydroxide."

My equation is as follows:

CO_2+2Ca\left(OH\right)_2\rightarrow C\left(OH\right)_4+Ca_2O_2

...after doing the work out, I come up with this net ionic equation:

C^{+4}+4OH^{-}\rightarrow C\left(OH\right)_4

Did I do this correctly?

No apm. Notice that the oxidation state of Ca in Ca2O2 is +1. This is not possible.

Also, if you write the equation with H2CO3 (as suggested by scrappychic) instead of CO2, it's easier to see that this is nothing but a neutralization reaction.

 

[scrappychic]

One thing that might help you in the future is to know that carbon usually does not form ionic compounds (examples are beyond the scope of what you are doing in this problem). The oxygen does not dissociate from carbon, because CO2 is covalent. Even though you may not have heard of carbonic acid, know that covalent compounds do not dissociate into ions, so you will have to find another method to get the overall reaction.