Question #9a596

1 Answer
Mar 26, 2016

Answer:

Here is the final balanced form of the equation:

#2KMnO_4+16HCl→2KCl+2MnCl_2+8H_2O+5Cl_2#

Steps are outlined below.

Explanation:

Start with this unbalanced equation:

#KMnO_4+HCl→KCl+MnCl_2+H_2O+Cl_2#

Perhaps a simple table will help make it clearer what we need to do:

Element - Amount on the left - Amount on the right

K - 1 - 1
Mn - 1 - 1
O - 4 - 1
H - 1 - 2
Cl - 1 - 5

Clearly we need more Cl on the left, and the only place it can come from is the HCl. Let's take 5 of those:

#KMnO_4+5HCl→KCl+MnCl_2+H_2O+Cl_2#

Our table changes to:

Elmnt - Amt left - Amt right

K - 1 - 1
Mn - 1 - 1
O - 4 - 1
H - 5 - 2
Cl - 5 - 5

You can see both H and Cl changed.

Now, on the right, the only place H is going is into the #H_2O#. We can take #5/2# of those if we want to (we're talking moles, not molecules), and that's what will balance the H, like so:

#KMnO_4+5HCl→KCl+MnCl_2+5/2H_2O+Cl_2#

Our table changes to:

Elmnt - Amt left - Amt right

K - 1 - 1
Mn - 1 - 1
O - 4 - 5/2
H - 5 - 5
Cl - 5 - 5

You notice both H and O changed.

I dunno, though, fractions are messy. I think I'm going to multiply everything by 2 to make it clearer:

#2KMnO_4+10HCl→2KCl+2MnCl_2+5H_2O+2Cl_2#

Our table changes to:

Elmnt - Amt left - Amt right

K - 2 - 2
Mn - 2 - 2
O - 8 - 5
H - 10 - 10
Cl - 10 - 10

Tricky! We need more O on the right side, so let's just go from 5 to 8 on the #H_2O#:

#2KMnO_4+10HCl→2KCl+2MnCl_2+8H_2O+2Cl_2#

Our table changes to

K - 2 - 2
Mn - 2 - 2
O - 8 - 8
H - 10 - 16
Cl - 10 - 10

OK, we fixed the O but now we have an issue with the H. Let's change the HCl on the left from 10 to 16:

#2KMnO_4+16HCl→2KCl+2MnCl_2+8H_2O+2Cl_2#

Our table changes to

K - 2 - 2
Mn - 2 - 2
O - 8 - 8
H - 16 - 16
Cl - 16 - 10

Change the coefficient on the #Cl_2# to balance up the Cl - it's convenient because it doesn't change any other element:

#2KMnO_4+16HCl→2KCl+2MnCl_2+8H_2O+5Cl_2#

Our table changes to

K - 2 - 2
Mn - 2 - 2
O - 8 - 8
H - 16 - 16
Cl - 16 - 16

And yay! Everything is balanced!

This is probably one of the gnarliest equations to balance, and it takes a lot of steps, but staying calm and clear makes it quite doable.