Question

Calculate [H+] in 0.375M H2PO4 Ka=6.2x10^-8

I know I'm suppose to write the equation first, but I'm not sure if I did it right:

H2PO4 + H2O <=> 2H+ + PO4

is that right?

You need to clarify the question. Is that a salt, such as KH2PO4, that is 0.375 M or is it the ion H2PO4^-. Is the Ka listed actually k2 for H3PO4? And is this part of a larger problem? The (H^+) for a salt such as KH2PO4 is sqrt (k1*k2).