Help Balancing Chemical Equations?
The first is the chemical equation for the reaction that occurs between nitric acid and magnesium hydroxide. I think the unbalanced equation is : HNO3 + MgOH = MgN + H2O.
The second is for the reaction between HNO3 and PH3.
Any help balancing these equations is deeply appreciated.
Favorite Answer
2PH3 + 16 HNO3 —> P2O5 + 16NO2 + 11H2O
1. The only subscripts that are to be carried over From the left side to the right side are the ones with polyatomic ions.
Here’s a list of them: http://www.woodrow.org/teachers/chemistry/links/chem1/PolyatomicIonsChart.html I would print it and put it in my notebook. It will come in VERY handy…
2. Do you remember the F.O.I.L. method from Algebra? If not here’s a site that will show it to you…: http://www.algebrahelp.com/lessons/simplifying/foilmethod/pg2.htm
You will be using the “O.I” part of it here. You put the 2 terms on the inside together and the 2 terms on the outside together when you are finding the part of the equation that comes after the arrow.
So that makes the first equation this:
H (NO3) + Mg (OH) = H (OH) + (NO3) Mg
3. Hydrogen is diatomic so when it is alone and on the right side of the equation, it always has a subscript of 2.
And the second equation is:
H (NO3) + PH3 = H P + (NO3) H
Ok so here’s how to balance the first:
H (NO3) + Mg (OH) = H (OH) + (NO3) Mg
Ask yourself how many “H” are there on the left? 1
and how many on the right? 1
They are equal so that part is balanced.
Ask yourself how many “(NO3)” are there on the left? 1
and how many on the right? 1
They are equal so that part is balanced.
Ask yourself how many “Mg” are there on the left? 1
and how many on the right? 1
They are equal so that part is balanced.
Ask yourself how many “OH” are there on the left? 1
and how many on the right? 1
They are equal so that part is balanced.
All of the terms are balanced so the equation is balanced.
Here’s how to balance the second:
H (NO3) + PH3 = H P + (NO3) H2
Ask yourself how many “H” are there on the left? 4
and how many on the right? 3
They are equal so that part is NOT balanced.
Ask yourself how many “(NO3)” are there on the left? 1
and how many on the right? 1
They are equal so that part is balanced.
Ask yourself how many “P” are there on the left? 1
and how many on the right? 1
They are equal so that part is balanced.
In order to balance the equation, you need to add coefficients to each term and continue to ask those same questions until each term is balanced.
Here is the balanced equation:
2H (NO3) + P H3 = H P + 2(NO3) H2
I hope this helps you—- if you don’t understand something, I’ll be happy to clarify. Good Luck!
