Looking for trustworthy answers? Westonci.ca is the ultimate Q&A platform where experts share their knowledge on various topics. Join our platform to get reliable answers to your questions from a knowledgeable community of experts. Get precise and detailed answers to your questions from a knowledgeable community of experts on our Q&A platform.

Calculate the pH of 720. mL of a 0.425-M solution of hydrocyanic acid before and after the addition of 0.249 mol of sodium cyanide.

Sagot :

The pH of hydrocyanic acid before and after the addition of sodium cyanide is 0.371 and 9.121

Calculation of pH of 720:

Given: Concentration of hydrocyanic acid (HCN) = 0.425 M

To find: pH

Reaction:

[tex]HCN \,\,\,\,\,\rightarrow \,\,\,\,\,\,H^+ + CN^-[/tex]

0.425M     0.425M

[tex]pH= -[logH^+]\\pH=-[log\,0.425]\\pH= 0.371[/tex]

pH after adding 0.249 mol of sodium cyanide (NaCN)

Pka of HCN= 9.21

Concentration of sodium cyanide = [tex]\frac{0.249}{0.720}\,M[/tex]

Concentration of NaCN= 0.346 M

According to Henderson–Hasselbalch equation:

[tex]pH= p_k_a + log\frac{salt}{acid}[/tex]

Putting the values in the above equation,

[tex]pH= 9.21 + log\frac{0.346}{0.425} \\\\pH= 9.21 - 0.089\\pH= 9.121[/tex]

Note: Pka value of HCN is assumed as 9.21

Learn more about Henderson–Hasselbalch equation here:

https://brainly.com/question/14408052

#SPJ4

We hope our answers were helpful. Return anytime for more information and answers to any other questions you may have. Thanks for using our platform. We aim to provide accurate and up-to-date answers to all your queries. Come back soon. Your questions are important to us at Westonci.ca. Visit again for expert answers and reliable information.