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Vicinity24

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## Homework Statement

Determine the pH of the solution (to 2 decimal points) after the addition of 50.0 mL of 2.5 M nitric acid (HNO3) to 500 mL of 0.500 M BIS−TRIS propane (C11H26N2O6), a weak base). Assume that the 5% approximation is valid and that the volumes are additive. The pKa of BIS−TRIS propane−H is 9.10.

## Homework Equations

Henderson-Hasselbach equation:

pH = pKa + log(nbase/nacid)

n being amount of moles

## The Attempt at a Solution

moles acid= (50.0mL/1000mL)*2.5M= .125 moles of acid

moles base= (500mL/1000mL)*.5M= .250 moles of base

Using henderson-hasselbach equation:

pH = 9.10 + log(.250/.125)

pH =

**9.4**

It is however, incorrect. I've had to do a set of these and I got those correct but not this one following the same format. I was curious if maybe I need to multiple the base by a certain molar ratio? I could not figure it out given the complicated equations though.

Thanks