Question

A 40.3 ml sample of a 0.587 m aqueous hydrocyanic acid solution is titrated with a 0.363 m aqueous sodium hydroxide solution. what is the ph after 19.9 ml of base have been added?

Answer 1

A 40.3 ml sample of a 0.587 m aqueous hydrocyanic acid solution is titrated with a 0.363 m aqueous sodium hydroxide solution. The pH after 19.9 ml of base have been added is 12

After 19.9 mL of NaOH have been added we have gone way past the equivalence point, so there is a lot of excess NaOH,

⇒ 40.3 - 19.9 = 20.4 mL excess

⇒ 0.0204 L (0.363 M)  = 0.0074 moles NaOH excess,

⇒ 0.0074 moles / (0.0199 + 0.0403)

⇒ 0.122 M NaOH at this point,

[OH]⁻ = [NaOH]

pOH = - log (0.122) = 2.103

pH = 14 - pOH = 11.897 = 12

Hence, pH = 12, After 19.9 mL base have been added.

To learn more about titration here

brainly.com/question/2728613

#SPJ4