1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
dmitriy555 [2]
3 years ago
11

To understand the relation between the strength of an acid or a base and its pKa and pKb values. The degree to which a weak acid

dissociates in solution is given by its acid-ionization constant, Ka. For the generic weak acid, HA, HA(aq)⇌A−(aq)+H+(aq) and the acid-ionization constant is given by Ka=[A−][H+][HA] Similarly, the degree to which a weak base reacts with H2O in solution is given by its base-ionization constant, Kb. For the generic weak base, B, B(aq)+H2O(l)⇌BH+(aq)+OH−(aq) and the base-ionization constant is given by Kb=[BH+][OH−][B] Another way to express acid strength is by using pKa: pKa=−logKa Another way to express base strength is by using pKb: pKb=−logKb Part A A new potential heart medicine, code-named X-281, is being tested by a pharmaceutical company, Pharma-pill. As a research technician at Pharma-pill, you are told that X-281 is a monoprotic weak acid, but because of security concerns, the actual chemical formula must remain top secret. The company is interested in the drug's Ka value because only the dissociated form of the chemical is active in preventing cholesterol buildup in arteries. To find the pKa of X-281, you prepare a 0.079 M test solution of X-281 at 25.0 ∘C. The pH of the solution is determined to be 2.40. What is the pKa of X-281?
Chemistry
1 answer:
elena-14-01-66 [18.8K]3 years ago
8 0

Answer:

pKa = 3.675

Explanation:

  • pKa = - Log Ka

∴ <em>C</em> X-281 = 0.079 M

∴ pH = 2.40

let X-281 a weak acid ( HA ):

∴ HA ↔ H+ + A-

⇒ Ka = [H+] * [A-] / [HA]

mass balance:

⇒<em> C</em> HA = 0.079 M = [HA] + [A-]

⇒ [HA] = 0.079 - [A-]

charge balance:

⇒ [H+] = [A-] + [OH-]... [OH-] is negligible; it comes from to water

⇒ [H+] = [A-]

∴ pH = - log [H+] = 2.40

⇒ [H+] = 3.981 E-3 M

replacing in Ka:

⇒ Ka = [H+]² / ( 0.079 - [H+] )

⇒ Ka = ( 3.981 E-3 )² / ( 0.079 - 3.981 E-3 )

⇒ Ka = 2.113 E-4

⇒ pKa = - Log ( 2.113 E-4 )

⇒ pKa = 3.675

You might be interested in
Write equation to represent the Hydrogenation reactions​
garik1379 [7]

Explanation:

vegetable oils have long unsaturated carbon chains which can converted into vegetable ghee

4 0
2 years ago
A chemist sets up a chemical reaction but finds that none of the reactant molecules have a required activation energy. What is t
Anvisha [2.4K]

Activation energy is the minimum amount of energy that the colliding reactant molecules must possess for the formation of products. Lower the activation energy, higher will be chance of formation of products. So activation energy is the minimum energy requirement that has to overcome for the reaction to be completed. Therefore, when in a chemical reaction the reactant molecules do not collide with required activation energy, the collisions will not be fruitful even if they are properly oriented which means that the products will not form.

Hence the correct answer will be B.) no products will be formed

5 0
3 years ago
Read 2 more answers
The mass number of an element is equal to
klasskru [66]

Answer:

The mass number is defined as the total number of protons and neutrons in an atom.

Explanation:

8 0
3 years ago
How many moles of MgSiO3 are in 237g of the compound?
Anna35 [415]
For this, we first calculate molecular weight of MgSiO₃:
Atomic masses:
Mg = 24
Si = 28
O = 16

Mr = 24 + 28 + 16 x 3
Mr = 100

moles = mass / Mr
moles = 237 / 100
moles = 2.37
6 0
3 years ago
Please help me please i will mark you brainliest. In the nucleus of an atom, there are 17 protons and 18 neutrons. What is the a
prohojiy [21]

Answer:

i can only help with 2 :( atimic mass is: 35.453  and number of electrons is:17

Explanation:

7 0
2 years ago
Other questions:
  • What promotes greater hardness in minerals? A smaller atoms and stronger bonds B larger atoms and weaker bonds C larger atoms an
    9·2 answers
  • If you are given 1.709 moles of solute, and you dilute it to make 2.10 liters of solution, what is the resulting molarity (M)? (
    14·1 answer
  • Identify each section of the periodic table.<br><br> metals<br> nonmetals<br> metalloids
    6·2 answers
  • 4NH3 + 502--&gt; 4NO + 6H 20
    5·1 answer
  • Calculate the boiling point of a 3.60 m aqueous sucrose solution. express the boiling point in degrees celsius to five significa
    10·2 answers
  • An increase in the elevation, or altitude, of a land mass causes
    11·1 answer
  • In a first-order decomposition reaction. 58.6% of a compound decomposes in 11.7 min. How long (in min) does it take for 80.2% of
    10·1 answer
  • The more quickly you change your _____, the more ____ you will have to exert
    7·1 answer
  • Elaine's teacher gave her two cubes and asked her to record as many observations as possible. The data table of her observations
    10·1 answer
  • Please help!!!
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!