1. A. Na+(aq) + NO3- (aq)  NaNO3(s) B. Ag+(aq) + CO32-(aq)  Ag2CO3(s)
QUESTION:
What is the net ionic equation for the precipitation reaction that occurs when Na2CO3(aq) and AgNO3 are mixed?
A. Na+(aq) + NO3- (aq)  NaNO3(s)
B. Ag+(aq) + CO32-(aq)  Ag2CO3(s)
C. Ag2+(aq) + CO32-(aq)  AgCO3(s)
D. 2 Ag+(aq) + CO32-(aq)  Ag2CO3(s)
Net ionic equation for a precipitation reaction shows:
Formula of precipitate (insoluble solid) on the product side
Formulas of ions that combined to form the precipitate on the reactant side.
Coefficients of ions corresponding to their subscripts in the precipitate.
What is the net ionic equation for the precipitation reaction that occurs when aqueous solutions of sodium carbonate and silver nitrate are mixed?
PAUSE
CLICK
A precipitate is a compound that is insoluble in water.
Therefore, to answer this question, we just need to look for a pair of ions that will form a compound that is insoluble in water.
We use solubility rules to predict whether a a compound is soluble or insoluble in water.
Sodium carbonate gives us sodium and carbonate ions.
CALLOUT “Na+ and CO32-” pointing to Na2CO3
Silver nitrate gives us silver and nitrate ions
CALLOUT “Ag+ and NO3-” pointing to AgNO3
According to our solubility rules… any compound containing sodium or nitrate ions are soluble in water.
Therefore, we do not expect our precipitate to have sodium or nitrate ions.
CROSS OUT Na+ and NO3- in callouts
Therefore, choice A is incorrect.
CROSS OUT NaNO3(s) in choice A.
Sodium nitrate is soluble in water. It will not be a precipitate.
Choice C is obviously wrong. The charge of silver ion is +1, not +2.
CROSS OUT Ag2+(aq)
Choice B and D show the correct reactants and products.
The product, silver carbonate, is insoluble in water according to the solubility rules.
The only difference between the two is that the equation in choice B is not balanced.
Therefore, the correct answer is choice D.
The net ionic equation for a precipitation reaction simply shows
CLICK the formula of the precipitate on the product side. In this case, silver carbonate
HIGLIGHT Ag2CO3(s) in choice D
CLICK the formulas of the ions that combined to form the precipitate on the reactant side
HIGHLIGHT Ag+(aq) and CO32-(aq) in choice D
… and to balance the equation… coefficients for the ions correspond to their subscript in the formula of the precipitate.
In the case given here, the subscripts of silver is 2 and that of carbonate is unwritten…. That is, the subscript of carbonate in silver carbonate is implied to be one.
So, a coefficients of 2 is written in front of silver ion and no coefficient is written in front of carbonate ion.
PAUSE END RECORDING

2. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08