Question

Calculate the pH of a buffer solution prepared by dissolving 0.20 mole of cyanic acid (HCNO) and 0.80 mole of sodium cyanate (NaCNO) in enough water to make 1.0 liter of solution.

Ka(HCNO) = 2.0 x 10^-4

Answer 1

The pH of a buffer solution : 4.3

Further explanation

Given

0.2 mole HCNO

0.8 mole NaCNO

1 L solution

Required

pH buffer

Solution

Acid buffer solutions consist of weak acids HCNO and their salts NaCNO.

`\tt \displaystyle [H^+]=Ka*(mole\:weak\:acid)/(mole\:salt* valence)`

valence according to the amount of salt anion

Input the value :

`\tt \displaystyle [H^+]=2.10^(-4)*(0.2)/(0.8* 1)\\\\(H^+]=5* 10^(-5)\\\\pH=5-log~5\\\\pH=4.3`