# Chemistry

A solution of aniline(C6H5NH2, Kb=4.2x10^-10) has a pH of 8.69 at 25 Celsius. What was the initial concentration of aniline?
I have so far don't know if it's right:
*. [H3O]=10^-8.69=2x10^-9
* 4.2x10^-10=(2x10^-9)^2 / x
X=1.2x10^-8 (correct???)

1. 👍
2. 👎
3. 👁
1. Aniline is a weak base, so I would tackle the problem this way.

14-pH=pOH

pOH=-log[OH]

Solving for OH concentration,

10^(-pOH)=OH concentration.

B + H2O----> BH + OH

Where B=aniline and BH= conjugate acid of aniline

So, Kb=[BH][OH]/B

The reaction shows that the concentration of OH= the concentration of BH, so the equation above becomes

kb=(OH concentration)^2/BH

Solving for BH,

BH=(OH concentration)^2/kb

1. 👍
2. 👎
2. You could have done it that way, but you would have to solve for ka=kw/kb.

And treat analine as the conjugate base after its protonated form was deprotanated.

1. 👍
2. 👎
3. I apologize, I have a typo.

kb=(OH concentration)^2/B

Solving for B,

B=(OH concentration)^2/kb

1. 👍
2. 👎

## Similar Questions

1. ### AP Chemistry

In a saturated solution of Zn(OH)2 at 25 degrees Celsius the value of [OH-] is 2.0x10^-6M. What is the value of the solubility-product constant, Ksp, for Zn(OH)2 at 25 degrees Celsius? A. 4x10^-18 B. 8x10^-18 C. 1.6x10^-17 D.

2. ### chemistry

calculate the weight of crystal formed on cooling 80 gm of saturated solution from 60 degree Celsius to 30 degree Celsius. solubility of salt at 60 degree Celsius and 30 degree Celsius are 132 and 95 respectively.

3. ### Chem

what is the hydronium-ion concentration at equilibrium in a 0.71 M solution of aniline (Kb=4.2x10^-10) at 25 Celsius

4. ### AP Chemistry

Which solution has the highest pH? 1. 0.1 M C6H5NH3Cl, Kb C6H5NH2 = 4.2 × 10−10 2. 0.1 M NH2(OH)2Cl, Kb NH2OH = 6.6 × 10−9 3. 0.1 M NaCl, Kb  zero 4. 0.1 M NH4Cl, Kb NH3 = 1.8 × 10−5 5. 0.1 M CH3NH3Cl, Kb CH3NH2 = 5.0 ×

1. ### vhem

What is the pH of a 0.570 M solution of aniline? Kb = 7.4 × 10-10

2. ### science

Written out, would the reaction between anihiline [C6H5NH2] and perchloric acid look like this: C6H5NH2 + HClO4 -> C6H5ClO4 + HNH2 ? The NH2 group on aniline is basic. It takes on a H^+ from HClO4 and forms the salt. The salt is

3. ### Chemistry- Empirical Formula

Aniline, consists of C, H, and N. Combustion of such compounds yields CO2, H2O, and N2. If the combustion of 9.71 mg of aniline yields 6.63 mg H2O and 1.46 mb N2, what is the empirical formula? What is the molecular formula of a

4. ### Chemistry

How much amount of crystal is formed when 15 gram of saturated solution prepared at 30 degree Celsius cooled to 10 degree Celsius. The solubility of that salt at 30 degree Celsius is 95 and at 10 degree Celsius

1. ### chemistry

What is the pH of a 1.24 mol/L solution of HCN(aq) if its Ka = 6.2 x 10-10? Rate my answer please For your understanding: HCN ⇌ H+ + CN-, Ka = 6.2x10^-10 = [H+]*[CN-]/[HCN] Notice the H+ and CN- ions are generated in pairs

2. ### chem

1. What is the [K+] of a solution prepared by dissolving 0.140 g of potassium hydroxide in sufficient pure water to prepare 250.0 ml of solution? 2. What is the pH of a 0.570 M solution of aniline? Kb = 7.4 × 10-10

3. ### Chemistry

In an experiment, 0.0300 moles each of SO3(g), S02(g), and O2(g) were placed in a 10.0L flask at a certain temperature. When the reaction came to equilibrium, the cocentration of SO2(g) in the flask was 3.50x10^-5 molar. What is

4. ### chemistry

Aniline (MW93 g/mol) co-distills with water 98.2 C. The vapor pressure of water at 98.2 C is 717 mmHg. You need to isolate 10 g of aniline. What is the minimum volume of water required to isolate 10 g of aniline in a steam