Net Ionic Equations: Balancing & Gases/Liquids

In summary, when heated, solid ammonium dichromate decomposes into solid chromium (III) oxide, nitrogen gas, and water vapor. The balanced equation is (NH4)2Cr2O7 (s) → Cr2O3 (s) + N2 (g) + 4H2O (g). In net ionic equations, gases and liquids are left unchanged, and for covalent molecules, they are also left unchanged if necessary.
  • #1
dnt
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Homework Statement



solid ammonium dichromate will produce (when heated) solid chromium (IV) oxide, nitrogen gas, and water vapor. Write the balance equation and net ionic equation.


Homework Equations



First i wrote:

(NH4)2Cr207 (s) --> CrO2 (s) + N2 (g) + H2O (g)

The Attempt at a Solution



first i just cannot balance this thing. I am usually very good at it but this one doesn't seem to work. do i have it written down correctly so far?

secondly, in net ionic equations, what do you do with gases (and liquids)? i know solids do not ionize so you do not change them. but in this case, are there ANY ions? how can i write a net ionic equation here?

also if the molecule is molecular (covalent) does it ionize at all or do you also just leave it? can it "dissolve" in solution (eg CO2)? i would assume you do not change it since it is made up of covalent bonds and not ionic ones. hence it written the same in the net ionic equations.

thanks for the help.
 
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  • #2
Don't worry - you can't balance the equation because there's a mistake in the problem. Ammonium dichromate, when heated, decomposes into chromium (III) oxide, nitrogen gas, and water vapor. The green color left behind is indicative of chromium (III) oxide. That should make things easier for you.
 
  • #3
thanks.

does anyone know the other questions? what do you do with gases and liquids for net ionic equations? what about covalent molecules?
 
  • #4
Just left them if necessary.

2H+ + Zn(s) -> H2(g) + Zn2+

Borek
 
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Related to Net Ionic Equations: Balancing & Gases/Liquids

1. What is a net ionic equation?

A net ionic equation is a chemical equation that only shows the participating ions and their respective charges in a reaction. It excludes any spectator ions that do not participate in the reaction.

2. How do you balance a net ionic equation?

To balance a net ionic equation, you first need to write the unbalanced equation for the reaction. Then, you must identify the types of ions involved and their respective charges. Next, balance the charges on both sides of the equation by adding coefficients to the compounds. Finally, check that the number of each type of atom is the same on both sides of the equation.

3. What is the difference between a gas and a liquid in a net ionic equation?

In a net ionic equation, gases are represented as molecules while liquids are represented as their constituent ions. Gases are also typically written in their gaseous state (e.g. H2 (g) instead of H2 (aq)).

4. Can net ionic equations be used for all types of chemical reactions?

Net ionic equations can be used for reactions involving ionic compounds, acids and bases, and precipitates. However, they cannot be used for redox reactions or reactions involving covalent compounds.

5. Why are net ionic equations important in chemistry?

Net ionic equations are important because they allow us to focus on the key components of a reaction and understand the underlying chemical process. They also help us to predict the products of a reaction and determine the limiting reagent.

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