What is the concentration of a 1:2 dilution of a 0.6 M NaHCO3 solution?

Answer 1

It depends upon what 1:2 means. There is confusion among even experienced on this. If 1:2 means 1 part NaHCO3 + 2 parts water, then the concn is
0.6M x (1/3) = ?

If you mean 1 part NaHCO3 + 1 part (to make 2), then the concn is
0.6M x (1/2) = ?

The following is a good web site to read, especially the last part of the post in which the difference between "factor" and "ratio" discussed.
http://www.protocol-online.org/biology-forums/posts/31255.html