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
katrin [286]
3 years ago
13

A titration of 25.0 mL of a solution of the weak base aniline, C6H5NH2, requires 25.67 mL of 0.175 M HCl to reach the equivalenc

e point.C6H5NH2(aq) + HCl(aq)--> C6H5NH3+ (aq) + Cl- (aq)The Kb for aniline, C6H5NH2, is 4.0 x10-10a. What was the concentration of aniline in the original solution?b. What is the concentration of C6H5NH3+at the equivalence point (AND after equilibrium is established)?c. What is the pH of the solution at the equivalence point?
Chemistry
1 answer:
Lorico [155]3 years ago
7 0

Answer:

a. 0.180M of C₆H₅NH₂

b. 0.0887M C₆H₅NH₃⁺

c. pH = 2.83

Explanation:

a. Based in the chemical equation:

C₆H₅NH₂(aq) + HCl(aq) → C₆H₅NH₃⁺(aq) + Cl⁻(aq)

<em>1 mole of aniline reacts per mole of HCl</em>

Moles required to reach equivalence point are:

Moles HCl = 0.02567L ₓ (0.175mol / L) = 4.492x10⁻³ moles HCl = moles C₆H₅NH₂

As the original solution had a volume of 25.0mL = 0.0250L:

4.492x10⁻³ moles C₆H₅NH₂ / 0.0250L = 0.180M of C₆H₅NH₂

b. At equivalence point, moles of C₆H₅NH₃⁺ are equal to initial moles of C₆H₅NH₂, that is 4.492x10⁻³ moles

But now, volume is 25.0mL + 25.67mL = 50.67mL = 0.05067L. Thus, molar concentration of C₆H₅NH₃⁺ is:

[C₆H₅NH₃⁺] = 4.492x10⁻³ moles / 0.05067L = 0.0887M C₆H₅NH₃⁺

c. At equivalence point you have just 0.0887M C₆H₅NH₃⁺ in solution. C₆H₅NH₃⁺ has as equilibrium in water:

C₆H₅NH₃⁺(aq) + H₂O(l) → C₆H₅NH₂ + H₃O⁺

Where Ka = Kw / Kb = 1x10⁻¹⁴ / 4.0x10⁻¹⁰ =

<em>2.5x10⁻⁵ = [C₆H₅NH₂] [H₃O⁺] / [C₆H₅NH₃⁺]</em>

When the system reaches equilibrium, molar concentrations are:

[C₆H₅NH₃⁺] = 0.0887M - X

[C₆H₅NH₂] = X

[H₃O⁺] = X

Replacing in Ka formula:

2.5x10⁻⁵ = [X] [X] / [0.0887M - X]

2.2175x10⁻⁶ - 2.5x10⁻⁵X = X²

0 = X² + 2.5x10⁻⁵X - 2.2175x10⁻⁶

Solving for X:

X = -0.0015 → False solution. There is no negative concentrations.

X = 0.001477 → Right solution.

As [H₃O⁺] = X, [H₃O⁺] = 0.001477

Knowing pH = -log [H₃O⁺]

pH = -log 0.001477

<h3>pH = 2.83</h3>

You might be interested in
Which chemical element has the shortest name?
wariber [46]

Answer:

deez nuttts

Explanation:

6 0
3 years ago
Read 2 more answers
Equilibrium describes the balance that results from a forward and reverse reaction proceeding at equal rates. Since reaction rat
Nitella [24]

Answer:

the reaction proceeds to a new equilibrium in the direction that offsets the change.Explanation:

7 0
3 years ago
Read 2 more answers
Select the correct answer. Which notation is used to represent a beta particle?​
trapecia [35]

Explanation:

I think the notation used to represent beta is B

3 0
3 years ago
What method would a geologist use to determine the approximate age of a rock found in a newly discovered formation?
shtirl [24]
Rock paper scissor and that is on Albert Einstein , he made that up because he is so freaking smart so there you go have a wonderful day
8 0
3 years ago
What does mass change to and what does it do
Nataly [62]

Answer:

Mass is the amount of matter in an object and does not change with location.

Explanation:

4 0
3 years ago
Other questions:
  • during her science fair project, mary discovered that solutions of ionic compounds in water conduct electricity. What type of in
    10·1 answer
  • A student observes what happens when two different aqueous solutions are mixed in a test tube. Which of the following observatio
    13·1 answer
  • Place the following atmospheric gases in order of abundance, from highest to lowest.
    9·1 answer
  • What is the molar mass of BF3
    5·1 answer
  • Report with correct significant figures in scientific notation <br>3.698 X 10^4÷1.85 X 10^2​
    10·1 answer
  • How does the structure of the steroid EXPLAIN the function of the steroid?
    7·1 answer
  • Semester Exams,Which Statement Best compares the two passages. Screenshot below,Giving Brainliest....
    12·2 answers
  • Which soil horizon contains the most organic matter?
    13·1 answer
  • If an engineer's greatest concern is specific impulse, which type of fuel should she use?
    9·1 answer
  • The passage below describes an experiment. Read the passage and then follow the instructions below.
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!