Balancing chemical equations with polyatomic ions doesn't have to be
problematic anymore. Hello everyone, I'm Melissa Maribel your personal tutor and
here are a few tips to make balancing so much easier. Tip number one keep
polyatomic ions together if they are the same on both sides
since SO4 is the same on both the reactant and product side then we keep
them together. OH is also the same on both sides so we'll keep that together
too. Let's list all the single elements and polyatomic ions on each side in the
same order to make balancing easier. Now we'll count how many of each element or
polyatomic ion there is on either side. Iron has a subscript of 2 so there are 2
irons. Note: Polyatomic ions in parentheses means there is more than one
and polyatomic ions which out parentheses means there's only one. So that
3 subscript tells us there are three SO4s, there is only 1 K and 1 OH since
OH is not in parenthesis. Moving to the product side, there's one iron, one SO4,
two K's and three OH's. Let's start with balancing the irons
since there are two irons on the reactant side and only one on the
products, we will place a 2 in front of the entire compound of iron hydroxide by
placing it to this distributes to iron and OH so we have two irons and two
times three which is six OHs, SO4 and K did not change on the product side. Now
we'll balance the SO4s by placing a 3 in front of potassium sulfate distribute
the 3 and we now have 6 K's and 3 SO4s and nothing else changed. To
balance the K's and OH's we will place a 6 in front of potassium hydroxide we now
have 6 K's and 6 OHs and nothing else changed and everything is balanced. Tip
number 2 whenever OH and H2O are on opposite sides
change the H2O to HOH. We'll rewrite H2O as HOH. Now let's list all the single
elements and polyatomic ions on each side in the same order. Count how many of
each element or polyatomic ion there is on either side. On the reactant side
there's one aluminum now this 3 subscript means there's three OHs, this
two subscript means there's two H's and there's only one SO4 since there are no
parentheses. On the product side there are two aluminum's, three SO4 since it's
in parenthesis, 1 H and 1OH. To balance the aluminum's we need a 2 in front of
aluminum hydroxide, distribute the 2 to the aluminum and OH and we now have
two aluminum's and 2 times 3 so 6 OHs and H and SO4 remain unchanged to
balance the OHs on the product side we will put a 6 in front of water. We now
have six H's and six OHs. The aluminum and SO4 remain the same. Note: If you have
the individual elements of hydrogen or oxygen balance those at the end.
So we'll balance SO4 by placing a 3 in front of H2SO4 and distribute the 3 to
the hydrogen and SO4. We now have 2 times 3 so 6 H's and 3 SO4s and this is
our balanced equation. You know I made these tips just for you so let me know
if they helped. You can keep practicing more examples right over here and
remember stay determined, you can do this!