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What is the pH of a buffer that consists of 0.100 M #HCOOH# and 0.540 M #HCOONa#?

The #pK_a# of formic acid is 3.74.

Answer 1

Wyatt Atkins

#pH# #># #3.74#

#pH = pK_a + log_10{[[A^_]]/[[HA]]}#

#pH = 3.74 + log_10{[0.540*mol*L^-1]/[0.100*mol*L^-1]}#

You are going to have to do the math.

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Answer 2

Cooper Anderson

To calculate the pH of the buffer, we can use the Henderson-Hasselbalch equation, which is pH = pKa + log([A-]/[HA]). Given that the pKa of HCOOH is 3.75, we can substitute the values into the equation: pH = 3.75 + log(0.540/0.100) = 3.75 + log(5.40) ≈ 3.75 + 0.732 = 4.482. So, the pH of the buffer is approximately 4.482.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.