Question

For the nitrous acid, HNO2, Ka= 4.0 x 10^-4. Calculate the ph of 0.27 M HNO2

For the nitrous acid, HNO2, Ka= 4.0 x 10^-4. Calculate the ph of 0.27 M HNO2

Homework Answers

Answer #1

HNO2 dissociates as:

HNO2 -----> H+ + NO2-

0.27 0 0

0.27-x x x

Ka = [H+][NO2-]/[HNO2]

Ka = x*x/(c-x)

Assuming x can be ignored as compared to c

So, above expression becomes

Ka = x*x/(c)

so, x = sqrt (Ka*c)

x = sqrt ((4*10^-4)*0.27) = 1.039*10^-2

since x is comparable c, our assumption is not correct

we need to solve this using Quadratic equation

Ka = x*x/(c-x)

4*10^-4 = x^2/(0.27-x)

1.08*10^-4 - 4*10^-4 *x = x^2

x^2 + 4*10^-4 *x-1.08*10^-4 = 0

This is quadratic equation (ax^2+bx+c=0)

a = 1

b = 4*10^-4

c = -1.08*10^-4

Roots can be found by

x = {-b + sqrt(b^2-4*a*c)}/2a

x = {-b - sqrt(b^2-4*a*c)}/2a

b^2-4*a*c = 4.322*10^-4

roots are :

x = 1.019*10^-2 and x = -1.059*10^-2

since x can't be negative, the possible value of x is

x = 1.019*10^-2

So, [H+] = x = 1.019*10^-2 M

use:

pH = -log [H+]

= -log (1.019*10^-2)

= 1.9916

Answer: 1.99

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
Calculate the pH of a 0.375 M aqueous solution of nitrous acid (HNO2, Ka = 4.5×10-4)...
Calculate the pH of a 0.375 M aqueous solution of nitrous acid (HNO2, Ka = 4.5×10-4) and the equilibrium concentrations of the weak acid and its conjugate base. pH =    [HNO2 ]equilibrium =    M [NO2- ]equilibrium =    M
In a titration of 100 mL 0.10 M Nitrous acid HNO2 (Ka= 4.5*10-4) against a 0.10...
In a titration of 100 mL 0.10 M Nitrous acid HNO2 (Ka= 4.5*10-4) against a 0.10 M Sodium hydroxide NaOH, calculate the pH at the equivalence point?
What is the pH of a 0.0520 M solution of nitrous acid (HNO2)? (Ka = 4.5...
What is the pH of a 0.0520 M solution of nitrous acid (HNO2)? (Ka = 4.5 x 10-4) (Hint: use ICE and solve the quadratic equation) OR something A LOT simple PLEASE Question options: a) pH = 2.34 b) pH = 2.32 c) pH = 2.30 d) pH = 2.36     
nitrous acid, HNO2, has a Ka of 7.1 x 10^-4. What are [H3O+], [NO2-], and [OH-]...
nitrous acid, HNO2, has a Ka of 7.1 x 10^-4. What are [H3O+], [NO2-], and [OH-] in 0.60 M HNO2?
Calculate the pH of a solution that is 0.322 M in nitrous acid (HNO2) and 0.178...
Calculate the pH of a solution that is 0.322 M in nitrous acid (HNO2) and 0.178 M in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50 × 10-4.
Calculate the pH of a solution that is 0.253 M in nitrous acid (HNO2) and 0.111...
Calculate the pH of a solution that is 0.253 M in nitrous acid (HNO2) and 0.111 M in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50 ⋅ 10-4. One of these answers is the correct one. 2.992 11.01 14.36 3.708 4.898
a. Calculate the pH of a 0.538 M aqueous solution of hydrofluoric acid (HF, Ka =...
a. Calculate the pH of a 0.538 M aqueous solution of hydrofluoric acid (HF, Ka = 7.2×10-4). b. Calculate the pH of a 0.0242 M aqueous solution of nitrous acid (HNO2, Ka = 4.5×10-4).
Nitrous acid has a Ka of 4.5×10−4. What is the pH of a buffer solution containing...
Nitrous acid has a Ka of 4.5×10−4. What is the pH of a buffer solution containing 0.16 M HNO2 and 0.12 M NO−2? I got 3.46 but it was wrong. Please help
1)consider a 1.50 M solution of nitrous acid,HNO2 (ka=6.0*10^-4) what is molarity of H^+? what is...
1)consider a 1.50 M solution of nitrous acid,HNO2 (ka=6.0*10^-4) what is molarity of H^+? what is the PH? 2) indiacte speices if its an acid or base? NH3 +h20 ...> <.... NH4+ +OH C7H502H +c6h5nh2 C75O2^- +C6H5NH3^+
1. 50.0 ml of 0.10 M HNO2 (Ka = 4.0 x 10-4) are being titrated with...
1. 50.0 ml of 0.10 M HNO2 (Ka = 4.0 x 10-4) are being titrated with 0.10 M NaOH. The pH after 25.0 ml of NaOH have been added is...? 2. If 25 ml of 0.75M HCl are added to 100 ml of 0.25M NaOH, what is the final pH? thank you!
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT