Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Anu on 02/04/2015 13:58:43

Title: How do you balance chemical reactions?
Post by: Anu on 02/04/2015 13:58:43
I was given a homework problem to balance the equation

Mg(NO3)2 + K3PO4 = Mg3(PO4)2 + KNO3

I started with,

Mg = 2, 3

NO = 6, 3

K = 3, 1

PO = 4, 8

Adding 2 to KNO3,

Mg(NO3)2 + K3PO4 = Mg3(PO4)2 + 2KNO3

Mg = 2, 3

NO = 6, 6

K = 3, 2

PO = 4, 8

After this i cannot balance..
Title: Re: Balancing Chemical Equations
Post by: Catherine123 on 02/04/2015 14:03:01
Try with chemical equation balancer ( https://www.easycalculation.com/chemistry/balancing-equations.php )
Title: Re: Balancing Chemical Equations
Post by: Ethos_ on 02/04/2015 16:04:42
Quote from: Catherine123 on 02/04/2015 14:03:01
Try with chemical equation balancer ( https://www.easycalculation.com/chemistry/balancing-equations.php )
Excellent link Catherine,....should be quite handy for those seeking to solve chemical formulae. This site also provides many math and physics calculators, should be very helpful for those less skilled in those areas.

Many thanks Catherine.......................Ethos

And welcome to the forum...............enjoy!
Title: Re: Balancing Chemical Equations
Post by: SorryDnoodle on 02/04/2015 22:06:48
Quote from: Catherine123 on 02/04/2015 14:03:01
Try with chemical equation balancer ( https://www.easycalculation.com/chemistry/balancing-equations.php )

Online help is great, but I advice everyone to not depend on the easy way out, learn how to balance properly and especially things like calculating morality, concentration etc.. These are some of the basics of calculating chemistry, learn them to heart.
Title: Re: Balancing Chemical Equations
Post by: alancalverd on 02/04/2015 23:13:25
I always approach chemical equations sequentially, and try to build the largest product molecule first. Why not start with the first nuclide on the left- Mg

Since you need to end up with 3 magnesiums on the right, you need to start with  3 magnesiums on the left.

First try: 3Mg(NO3)2 + ?K3PO4 = Mg3(PO4)2 + ?KNO3

Now you have 3 x 2 = 6 nitrates on the left, so you will end up with 6 on the right

Second try: 3Mg(NO3)2 + ?K3PO4 = Mg3(PO4)2 + 6KNO3

So you need 6 potassiums on the left

Third try: 3Mg(NO3)2 + 2K3PO4 = Mg3(PO4)2 + 6KNO3

Lo and behold, you now have 2 phosphates each side and the equation balances.

The trick is: don't panic! If the equation completely describes the reaction, every atom on the left will eventually appear on the right.