# Problem: The Ka of nitrous acid, HNO2, is 4.5x10-4. What [NO2-]/[HNO2] ratio is necessary to make a buffer with a pH of 3.71?a) 1.9 x 10-8b) 0.45c) 0.76d) 1.5e) 2.3

###### FREE Expert Solution
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###### FREE Expert Solution

Since the solution is a buffer, we can use the Henderson-Hasselbalch Equation to calculate the ratio of [NO2-]/[HNO2] to have a pH of 3.71:

In the solution, identify the weak acid and the conjugate base. Recall from the Bronsted-Lowry definition that an acid is a proton (H+) donor and the base is a proton (H+) acceptor.

82% (143 ratings)
###### Problem Details

The Ka of nitrous acid, HNO2, is 4.5x10-4. What [NO2-]/[HNO2] ratio is necessary to make a buffer with a pH of 3.71?

a) 1.9 x 10-8

b) 0.45

c) 0.76

d) 1.5

e) 2.3

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Buffer concept. You can view video lessons to learn Buffer. Or if you need more Buffer practice, you can also practice Buffer practice problems.

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Based on our data, we think this problem is relevant for Professor Holme's class at ISU.