# Chemistry II

posted by .

Calculate the pH at the equivalence point in the titration of 50ml of 0.20 M methylamine (Kb=4.3*10^-4) with a 0.40 M HCL solution.

• Chemistry II -

How many mL HCl is needed? That's
50 x 0.2/0.4 = 25.00 mL
Total volume = 75.00 mL
Total mols = 0.050 x 0.2 =0.01
(salt at equivalence point) = 0.01/0.075L = approximately 0.13
If we call methylamine just BNH2 then the salt will be BNH3^+ and it will hydrolyze as follows:

......BNH3^+ + H2O ==> H3O^+ + BNH2
I.....0.13..............0........0
C.......-x..............x........x
E...-0.13-x.............x........x

Ka for BNH3^+ = (Kw/Kb for BNH2) = (x)(x)/(0.13-x)
Solve for x = (H3O^+) and convert to pH.

## Similar Questions

1. ### chemistry

Q.1 What will be the pH at the equivalence point during the titration of a 100 ml 0.2M solution of CH3COONa with 0.2M of solution of HCl?
2. ### Chemistry

Calculate the pH at the equivalence point for the titration of 0.120 M methylamine with 0.120 M HCl (kb of methyalamine is 5.0 x 10^-4)
3. ### Chemistry!!

Calculate the pH at the equivalence point for the titration of 0.180 M methylamine (CH3NH2) with 0.180 M HCl. The Kb of methylamine is 5.0Ã— 10^â€“4.
4. ### Analytical Chemistry

Calculate the pH at the equivalence point for the titration of 0.160 M methylamine (CH3NH2) with 0.160 M HCl. The Kb of methylamine is 5.0× 10–4. Methylamine is a weak base and reacts with HCl to give the methylammonium ion. HCl …
5. ### Chemistry

Calculate the pH at the equivalence point for the titration of 0.200 M methylamine (CH3NH2) with 0.200 M HCl. The Kb of methylamine is 5.0× 10–4.
6. ### chemistry

CH3NH2(aq)+H2O(l)=>CH3NH3+(aq)+OH-(aq) Kb=4.4 x 10^-4 Methylamine, CH3NH2, is a weak base that reacts with water according to the equation above. A student obtains a 50.0 mL sample of a methylamine solution and determines the pH …
7. ### AP Chemistry

CH3NH2(aq)+H2O(l)=>CH3NH3+(aq)+OH-(aq) Kb=4.4 x 10^-4 Methylamine, CH3NH2, is a weak base that reacts with water according to the equation above. A student obtains a 50.0 mL sample of a methylamine solution and determines the pH …
8. ### Chemistry

Calculate the pH at the equivalence point for the titration of 0.180 M methylamine (CH3NH2) with 0.180 M HCl. The Kb of methylamine is 5.0× 10–4.
9. ### CHemistry

Calculate the pH at the equivalence point for the titration of 0.140 M methylamine (CH3NH2) with 0.140 M HCl. The Kb of methylamine is 5.0× 10–4.
10. ### College Chemistry

Calculate the pH at the equivalence point in the titration of 55.0 mL of 0.180 M methylamine(Kb = 4.4 × 10−4) with 0.330 M HCl.

More Similar Questions