menu
bartleby
search
close search
Hit Return to see all results

How do you get a Pka?

Question

How do you get a Pka? 

check_circleAnswer
Step 1

Dissociation constant (Ka) is the equilibrium constant of a reaction which depicts the dissociation of a proton from a weak acid. 

For example, a weak acid i.e. HA dissociates as per following reaction:

HA  + H2O <-----> H3O+ + A-

The Ka of above reaction can be written as:

 

[Н:0'JA]
К.
[НA]
help_outline

Image Transcriptionclose

[Н:0'JA] К. [НA]

fullscreen
Step 2

pKa  stands for the negative logarithm (to base 10) of Ka . 

Mathematically, it is written as pKa  = -log (Ka ).

So, to calculate pKa  , negative logarithm of Ka  is to be calculated.

Step 3

pKa can also be observed on titration curve of weak acid with strong base. 

On plotting the curve between the pH of solution and volume of strong base added, the pH at half equivalence point is the pKa.

Equivalence point is that at which the pH of the solution rises abruptly on adding small amount of base. At this point, the moles of weak acid are equal to the moles of strong base in the reaction mixture.

Half equivalence point is that at which &nb...

Want to see the full answer?

See Solution

Check out a sample Q&A here.

Want to see this answer and more?

Our solutions are written by experts, many with advanced degrees, and available 24/7

See Solution
Tagged in

Science

Chemistry

Equilibrium Concepts

Related Chemistry Q&A

Find answers to questions asked by student like you

Show more Q&A add
question_answer

Q: Comment on the difference between the enthalpy of combustion values of anthracene, napthalene, and p...

A: Enthalpy of combustion of naphthalene (∆H) = -5138.8 20 KJEnthalpy of combustion of Anthracene (∆H) ...

question_answer

Q: Carbon dioxide and water react to form methanol and oxygen, like this: 2CO2(g) + 4H2O(g) → 2CH3OH(l...

A: It is given that:Mass of carbon dioxide (CO2) = 3.28 gMass of water (H2O) = 3.86 gMass of methanol (...

question_answer

Q: Give the number of atoms of the specified element in the formula unit of the following compound and ...

A: Leadhillite is a mineral of lead having the formula Pb4SO4(CO3)2(OH)2.

question_answer

Q: .3126 g sample of oxalic acid, H2C204, requires 26.21 mL of a particular concentration of NaOH(aq) t...

A: The given balanced chemical reaction is given as:H2C2O4 (s) + 2 NaOH (aq) → Na2C2O4 (aq) + 2 H2O (l)...

question_answer

Q: Barium metel was quantitatively precipitaded from 1.52g sample of BaCl2+2H2O. The mass of the barium...

A: Mass percentage = (mass of solute / mass of solution) x 100%

question_answer

Q: What mass of SbF3 (179 g/mol) is needed to produce 1.00 g of Freon-12, CCl2F2 (molar mass = 121 g/mo...

A: The balanced equation of the reaction is given and the moles of CCl2F2 is calculated as shown,

question_answer

Q: The level of mercury in a stream was suspected to be above the minimum considered safe (1 part per b...

A: The mass and moles of mercury are calculated as,

question_answer

Q: Complete the following statements: a. The atomic number gives the number of _______ in the nucleus. ...

A: The number of protons, neutrons and electrons which make up a neutral atom has to be given. A neutra...

question_answer

Q: Question 3

A: Double salt contains more than one cation or anion. Double salt completely dissociates into simple i...

Sorry about that. What wasn’t helpful?