[tajacks2]

I am not sure how to change the Ka1 and Ka2 when the temperature changes.

The problem is Calculate the molar concentration of HCO3- in a solution at 20 ºC when CT is 3 x 10-3 mol L-1 and pH = 6.2.

I think I know how to set it up right, I just don't know how to change the Ka from 25 degrees to 20.

Any help will be greatly appreciated. Thanks

[Borek]

Are you sure you need to use Ka corrected for temperature? Changes of Ka value are small and usually omitted in this types of calculations. What segment are you doing?