Question

Hey guys, I am having a lot of trouble with my homework. Could you please help? I thumbs up anyone who gives a thorough explanation and shows the work! I really need to understand these concepts!

1) The Ka for HCN is 4.9 ~ 10-10. What is the value of Kb for CN-? 2) Using the data in the table for 0.10 M aqueous species at 25 °C, which conjugate base below is the weakest base? Explain your answer for full credit! Acid ка. НОАс 1.8 x 10-5 HC7H502 6.3 10-5 HNO2 4.5 x 10-4 HF 6.8 x 10-4 3) The Ka for HCN is 4.9 10-10. What is the pH of a 0.068 M aqueous solution of potassium cyanide?

Thank you guys!

Answer 1

Acid is the species having tendency to lose H+. Formed anioñ is called conjugate base.

Ka is acid dissociation constant & Kb is base dissociation constant.

* Lower the Kb value, lower the basisity.

* KCN is salt made by strong base & weak acid, so it's formula is applied to find out pH .
I. Ka Ž (HCN) = 4.9 X1010 ta HCN Aced 2 H+ + CN conjugate base for an acid - Conjugate base pair ... Ra Caced ). Ko (conjugate bouse) Ka (HCN). Kb CCN) = 10 14 (4.9 X10'') Rocco) = 1614 Putting values- 26 Kb (CN) = 2,04 x 10 xios Ang 2. find out Rs of conjugate base derwest the kby weakest the conjugate bese 700 1,8 xios c) HOAC Ka= conjugate base CO Àc): Ky = - S.56x1610 Kauno b) HG Hg O2 is 10-14 -10 -1.59x16 Ka .). Conjugate base (G4503); HNO2 : conjugate base (ne);K 10014 = 2.22x10-11 Kan trust d) H ) 10:14 conjugate base (of); Ky= 1.47 X16" Ka HF has smallest Kb value = 1147x10-11 f is weakest conjugate base Ans (el) HiFi CS Scanned with CamScanner

weak acid HCN -10 Ka = 4.98151 concentration of KON 0.06 AM (0) KCN: Salt made by weak aced f strong babe CHCN) (KOH) formula: ph = 7+ Ž [pka + k log c] praa - 9.31 - log (Ra) = - log (4.9x1000) ... ph - 7+ Ź(9.31 + log 10.060)) ph = 1 Ang CS Scanned with CamScanner