Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Net ionic equations

  1. Jan 22, 2007 #1


    User Avatar

    1. The problem statement, all variables and given/known data

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

    2. Relevant equations

    First i wrote:

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

    3. The attempt at a solution

    first i just cannot balance this thing. im usually very good at it but this one doesnt 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.
  2. jcsd
  3. Jan 22, 2007 #2


    User Avatar

    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.
  4. Jan 23, 2007 #3


    User Avatar


    does anyone know the other questions? what do you do with gases and liquids for net ionic equations? what about covalent molecules?
  5. Jan 26, 2007 #4


    User Avatar

    Staff: Mentor

    Just left them if necessary.

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

    Last edited by a moderator: Aug 13, 2013
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook