Question

I want to make a solution that will have [HCOO ^- ] = 3[HCOOH]. I start with 100ml of a 0.1M HCOOH solution. How many ml of a 1M KOH solution should I add?

1. 5ml
2. 7.5ml
3. 25ml
4. 75ml

Answer 1

HCOOH + KOH - Ho0 AKT & H₂O. Imole Hoo formation requires Imole kot Hoo formation requires 705x103 mole koh . 7.5x10 3 mole the given Hence, we got the moles of koH required for condition, ie [H200- ) = 3 [H WOOH ] Now, IM KOH means, I mole KOH is in 1000 m2 Koh soln 7.5x 103 mole KOH will be in (1000 x7.5x103) mL 7.5 mL Soo have to add option - 2 is 7.5 mL of KOH should the correct answer

아 A lets motes HCOOH after reaction = x mote i. moles of 400 after reaction= 3x mole. moles of HCOOH before reaction = moles of Hook after reaction + moles of Hoŏ after xxn. 0.01 mole = x mole + 32 more : 4x = 0.01 x=2058103. mon after reaction = 205x10 3 son moles of HooH Hoo " tion - 205810 3 more and " = 3x 205 x 103 more = 7.5x10 3 more

HCOOH (aq) + KOH(aq) - Hoo (aq) + k + (aq) + H20(1) Orl M HCOOH soln means 1000ml som contains Ool mole HCOOH 100 mL DD Go X100) mole HCOOH 1ooo 0.01 mole HCOOH of Oolm HCOOH So, before the reaction with KOH & 100 mL son was containing 0.01 mole HCOOH after the reaction & [H600-] = 3 [HCOOH]