Question

1.When a 15.1 mL sample of a 0.479 M aqueous nitrous acid solution is titrated with a 0.483 M aqueous sodium hydroxide solution, what is the pH after 22.5 mL of sodium hydroxide have been added?

2.A 21.6 mL sample of 0.214 M diethylamine, (C₂H₅)₂NH, is titrated with 0.256 M perchloric acid.
The pH before the addition of any perchloric acid is

Answer 1

☺ Moles of nitrous a aid = 0.479 M X 15-1816 2 = 0.0072329 males ( Wegk 94d Males of 22591 of OH jons = 0·483M X 22:5X10ML = 0.01086 75 males Exc088 of males of SH jonka Co.018675—0.0072329) moles = 0.0036346 moles Total volume = (15.1 +22.5 mL - 37.6ml Meloity of OH = 0.0036346 moles -37.68103 L = 0.0966M So, Pole - log, COHO) =) pOH = -logo (0.0966) = 1.01 them, pH= 14-1001 2 pH = 12.99=13

② In the solution only diethylamine is present. So (C2H5NH + H2O 04+ Cettshith Initial o.214M - Equili (0-214->) M - X X So, Kb-0-219 -0.214x = 6.9x104 => 2276-9 xlolx – 1.4766x1ŐLO sor. r_ -69x10° + (6.9 xjö1) 44X1 .47667164 8x1 only +ve volen, x= 0.0118 M=cHe?" ther, pol= - lofjo COHO) = -logo Co-0118 M) = 1.92 € So, PH = 14-pOH = 14–1.92 =) pH=12-08