[shaggybill]

This is probably a simple question, but I was under the impression that subscripts could never be changed. However, here's a problem I'm working on now, with the answer from the book.

Write a balanced molecular equation for H2CO3 carbonic acid and KOH potassium hydroxide.

Answer: H₂CO₃ + 2KOH -->  2H₂O + K₂CO₃

In the last product, they've added a 2 as a subscript on potassium. Is that permissible?

Thanks,
Mitch

[nj_bartel]

You're misunderstanding that statement.

What you're thinking of is:  You cannot change a subscript of a compound without changing that compound.

K₂ just means you have two potassiums in that compound rather than 1, as in your previous compound, which is perfectly fine because your first compound underwent a reaction.

[shaggybill]

Ohhhh, I see. It's K₂ because CO3 is 2-. There needs to be two of them to make the compound neutral. I was thinking they added the 2 subscript while they were balancing the equation.

Awesome. Thanks for your help. I wasn't thinking clearly.