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Course: AP®︎/College Chemistry > Unit 8

Lesson 6: Buffers
Science
AP®︎/College Chemistry
Acids and bases
Buffers
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Buffers

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Problem

A student prepares a buffer by combining samples of HCN(aq) and NaCN(aq). A particle view of the buffer solution is shown below. Water molecules and cations are not depicted.
A large square contains particle representations of 12 structures scattered all over the square with large distances between them. Four of the structures are similar and each is represented by a bigger shaded circle adhering to a smaller white circle. The other eight structures are similar and each is represented by a big shaded circle. The key rectangle shows that each big shaded circle adhering to a small white circle = H C N and each big shaded circle = C N negative one.
Which of the following is true about the pH of the buffer? (The pKa of HCN is 9.21.)
Choose 1 answer: