Writing net ionic equations (having problems)

In summary, the conversation discussed three balanced equations that need to be written as net ionic equations. The first equation was found to be unbalanced and was corrected by separating the solid compound and removing spectator ions. The second equation involved determining the correct number of OH- ions needed to balance the charge of Ba2+. Finally, the third equation was not yet attempted due to struggling with the first two. The expert provided guidance and clarified the use of parentheses in chemical equations.
  • #1
mousechild
2
0
We have been given three balanced equations to write as net ionic equations. Our teacher forgot to teach us this bit and has now left the college. I'm really stuck, any help would be so kindly appreciated TY x



The equations are:

1. Pb(NO3)2 (aq) + 2KCl (aq) = PbCl2(s) + KNO3 (aq)

2. 2HCL(aq) + Ba(OH)2(aq) = BaCl2(aq) + 2H2O(l)

3. NaCl(aq) + AgNO3(aq) = NaNO3(aq) +AgCl(s)




With the first equation I don't think it is balanced, so I tried to firstly balance it by writing:

Pb(NO3)2(aq) + 2KCL(aq) = PbCl2(s) + 2KNO3(aq)

Then I attempted to write it ionically:

[Pb]2+ + 2[NO3]- + [K]+ + [Cl]- = [Pb]+2 + 2[Cl]- + 2[K]+ + 2[NO3]-


for the second one I got as far as writing: 2[H]+ + 2[Cl}- but I am very unsure of how to write Ba(OH)2. Is there 2 lots of Ba and 2 lots of OH? I don't understand why the OH is in brackets. :(

I haven't started trying to figure out the third question yet, I've spent hours trying to work out how you do the first two and I'm getting in a bit of a panic.


If you have been so kind as to take the time to read my problem (I know it's long and I sound like a complete idiot!) then thanks so much, and if you could help me then even more thanks. xx


 
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  • #2
Generally, whenever you see a solid, liquid, or gas in a chemical equation, that compound does not separate into ions in the net ionic equation. So in your first one, don't separate PbCl2. Then you cross out the spectator ions, or the ions that appear on both sides of the equation, and what you have left makes the net ionic equation.

For Ba(OH)2 in 2, think about the charges of the ions: Ba2+ and OH-. You need two OH- ions to balance the charge of Ba2+.
Subscripts after parentheses apply only to what is inside the parentheses.
 
  • #3
Thanks so much Bohrok, it's starting to make sense (I think!)...for the first one I have got:

Pb2+ + 2Cl- = PbCl2

and for the second:

2H+ + 2OH- = 2H2O

and for the third:

Cl- + Ag+ = AgCl am I correct? x
 

What is a net ionic equation?

A net ionic equation is a chemical equation that shows only the species that are directly involved in a chemical reaction. It excludes spectator ions, which are present in the reaction but do not participate in it.

Why is it important to write net ionic equations?

Writing net ionic equations allows us to focus on the essential components of a reaction and better understand the changes that occur. It also helps to simplify complex reactions and make them easier to balance.

How do I determine which ions are spectator ions?

Spectator ions are typically ions that are present on both the reactant and product side of the equation and do not undergo any chemical changes. They can be identified by looking at the solubility rules and determining which ions form insoluble compounds.

What are the steps to writing a net ionic equation?

The steps to writing a net ionic equation are as follows:

  1. Write the balanced molecular equation, including all reactants and products.
  2. Identify any strong electrolytes (compounds that dissociate completely in water) and break them into their constituent ions.
  3. Cancel out any spectator ions that appear on both sides of the equation.
  4. Write the net ionic equation using the remaining species.
  5. Double check that the equation is balanced.

What are some common mistakes when writing net ionic equations?

Some common mistakes when writing net ionic equations include:

  • Forgetting to balance the equation.
  • Using incorrect formulas or charges for ions.
  • Not canceling out spectator ions.
  • Incorrectly identifying strong electrolytes.
  • Forgetting to include states of matter (s, l, g, aq) for each species.

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