- #1

lha08

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## Homework Statement

A sample of arterial blood was found to contain 2.6 X 10

^{-2}mol/L dissolved CO

_{2}. The pH of the sample was 7.43. If it is assumed that in solution the CO2 forms H2CO3, what is the HCO3- concentration in this blood sample? (pKa for H2CO3 is 6.1)

## Homework Equations

## The Attempt at a Solution

so i first used the henderson hasselbalch equation for the equilibrium H2CO3 <-> HCO3- and then 7.43= 6.1 +log (A-)/(HA) and i got to 21.4= (HCO3-)/(H2CO3). Everything up to here i got, but then in the answer is said to let x= [HCO3-] and therefore 21.4= x / ((2.6X 10^-2)-x)...why do we have to subtract the x from the bottom?