Untitled - Kelly Walsh High School

66 CHEMISTRY FOR THE UTTERLY CONFUSED
Don’t Forget!
2 H 2 (aq) 2 NO 3 (aq) Ba (aq) 2 OH (aq)
l Ba 2 (aq) 2 NO 3 (aq) 2 H2O(l)
2 Li (aq) 2 F (aq) 2 H 2 (aq) SO 4 (aq)
l 2 Li 2 (aq) SO 4 (aq) 2 HF(aq)
When canceling, identical means identical. For example, Ca is not identical to Ca 2 .
You will notice that in the second reaction, all species cancel. This will require
us to amend our molecular equation to:
KCl(aq) (NH 4) 3PO 4(aq) l No Reaction (NR is commonly used)
We can now rewrite the ionic equations without the cancelled species to have
the net ionic equations:
Cr(OH) 3(s) 3 H (aq) l Cr 3 (aq) 3 H 2O(l)
KCl(aq) (NH 4) 3PO 4(aq) l NR
CO 3 2 (aq) 2 H (aq) l CO2(g) H 2O(l)
Mg 2 (aq) 2 OH (aq) l Mg(OH) 2(s)
2 H (aq) 2 OH (aq) l 2 H 2O(l)
2 F (aq) 2 H (aq) l 2 HF(aq)
The last two equations need further simplification by reducing the coefficients
by the common factor of two. The final net ionic equations are:
Cr(OH) 3(s) 3 H (aq) l Cr 3 (aq) 3 H 2O(l)
KCl(aq) (NH 4) 3PO 4(aq) l NR
CO 3 2 (aq) 2 H (aq) l CO2(g) H 2O(l)
Mg 2 (aq) 2 OH (aq) l Mg(OH) 2(s)
H (aq) OH (aq) l H 2O(l)
F (aq) H (aq) l HF(aq)
This method will work for most reactions. However, if a redox reaction is occurring,
an additional consideration is necessary. At this point, the presence of