# Predicting and Writing Net Ionic Equations for Chemical Reactions

• mcandrewsr
For example, sulphate is 2- charge (unless it is on a metal in the same group as lead, etc) and nitrate is 1-.The BobIn summary, for the given reactions, only a) and d) are likely to occur and their net ionic equations are: a) Cr(s) + 3Ag+(aq) --> Cr3+(aq) + 3Ag(s)d) 2Al(s) + 3H+(aq) + 3SO4-2(aq) --> 2Al3+(aq) + 3SO4-2(aq) + 3H2(g)
mcandrewsr

## Homework Statement

For each of the following situations, identify those for which a reaction likely to occur. For those that do occur, white a net ionic equation.
a) Chromium dipped into silver nitrate.
b) Gold immersed in hydrochloric acid
c) Nickel pellets dropped into calcium acetate, Ca(C2H3O2)2.
d) Aluminum dropped into a bath of sulphuric acid.
e) Zinc dipped into a solution of lead(II) nitrate.

## The Attempt at a Solution

This is what I got:
a)Cr(s) + 2AgNO3(aq) --> Cr(NO3)2 + 2Ag(s)
Separate the aqueous ions:
Cr(s) + 2Ag(aq) + 2NO3(aq) --> Cr(aq) + 2NO3(aq) + 2Ag(s)
Then I'm supposed to remove the ions common to both sides...but
then I end up with none at all b/c each one is on both sides...?
b) no reaction
c) no reaction
d) 2Al(s) + 3H2SO4(aq) --> Al2(SO4)3(aq) + 3H2(g)
Here I get the same problem as in (a) when I separate them.
e) Zn(s) + Pb(NO3)2(aq) --> Zn(NO3)2(aq) + Pb(s)
Again, same problem...if I separate the aqueous ions and get rid of the common ones I end up with nothing.

What am I doing wrong? If someone can show me how to do this that would be great, thanks!

mcandrewsr said:

## Homework Statement

For each of the following situations, identify those for which a reaction likely to occur. For those that do occur, white a net ionic equation.
a) Chromium dipped into silver nitrate.
b) Gold immersed in hydrochloric acid
c) Nickel pellets dropped into calcium acetate, Ca(C2H3O2)2.
d) Aluminum dropped into a bath of sulphuric acid.
e) Zinc dipped into a solution of lead(II) nitrate.

## The Attempt at a Solution

This is what I got:
a)Cr(s) + 2AgNO3(aq) --> Cr(NO3)2 + 2Ag(s)
Separate the aqueous ions:
Cr(s) + 2Ag(aq) + 2NO3(aq) --> Cr(aq) + 2NO3(aq) + 2Ag(s)
Then I'm supposed to remove the ions common to both sides...but
then I end up with none at all b/c each one is on both sides...?
b) no reaction
c) no reaction
d) 2Al(s) + 3H2SO4(aq) --> Al2(SO4)3(aq) + 3H2(g)
Here I get the same problem as in (a) when I separate them.
e) Zn(s) + Pb(NO3)2(aq) --> Zn(NO3)2(aq) + Pb(s)
Again, same problem...if I separate the aqueous ions and get rid of the common ones I end up with nothing.

What am I doing wrong? If someone can show me how to do this that would be great, thanks!

Be careful when you cancel off spectator species, make sure that they are indeed the same thing!

Firstly, note that the silver and nitrate exist as IONS in solution i.e.:

AgNO3(aq) --> Ag+(aq) + NO3-(aq)

So make sure you include the charges. This then indicates that the silver (and chromium) species on each side are NOT the same i.e. Ag+(aq) is completely different from Ag(s), so you cannot cancel them off, so overall, you are left with:

Cr(s) + 3Ag+(aq) --> Cr3+(aq) + 3Ag(s)

How do I know the different charges of ions when they are in different states? Ex. How does Cr(s) have a different charge than the aqueous one? How do I figure this out for any others?

There are a set of elements that have set oxidation numbers (for example oxygen normally has an oxidation number of 2-). By using these, you can determine what the other charges are.

The Bob

mcandrewsr said:
How do I know the different charges of ions when they are in different states? Ex. How does Cr(s) have a different charge than the aqueous one? How do I figure this out for any others?

Cr(s) is not ionic.

Otherwise - use periodic table. But some things you will just have to remember.

## 1. What is a net ionic equation?

A net ionic equation is a chemical equation that shows only the participating ions and omit the spectator ions. It represents the actual chemical reaction that takes place in a solution.

## 2. How do you write a net ionic equation?

To write a net ionic equation, first write the balanced molecular equation, then identify and write the ionic compounds as their dissociated ions. Finally, cancel out the spectator ions on both sides of the equation to get the net ionic equation.

## 3. Why is writing net ionic equations important?

Writing net ionic equations is important because it allows us to focus on the actual chemical reaction occurring in a solution. It also helps in identifying the ions that are participating in the reaction and those that are present only as spectators.

## 4. What are spectator ions?

Spectator ions are ions that are present in a solution but do not participate in the chemical reaction. They remain unchanged on both sides of the equation and do not affect the overall reaction.

## 5. How do you determine spectator ions?

To determine spectator ions, write the balanced molecular equation and then the ionic compounds as their dissociated ions. Any ions that appear on both sides of the equation are spectator ions. Cancel them out to get the net ionic equation.

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