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
wolverine [178]
3 years ago
14

For the reaction: CH3NH2(aq) + H2O(aq) ⇌ CH3NH3 +(aq) + OH- Determine the change in the pH (ΔpH) for the addition of 6.7 M CH3NH

3Cl salt to a 4.7 M solution of CH3NH2, Kb=4.38 x 10-4 . View Available Hint(s) For the reaction: CH3NH2(aq) + H2O(aq) ⇌ CH3NH3 +(aq) + OH- Determine the change in the pH (ΔpH) for the addition of 6.7 M CH3NH3Cl salt to a 4.7 M solution of CH3NH2, Kb=4.38 x 10-4 . ΔpH=12.66 ΔpH=1.86 ΔpH=10.49 ΔpH=2.17
Chemistry
1 answer:
Korolek [52]3 years ago
4 0

Answer:

The change in the pH (ΔpH) is 2,17

Explanation:

The reaction:

CH₃NH₂(aq) + H₂O(aq) ⇌ CH₃NH₃⁺(aq) + OH⁻

kb = \frac{[OH^{-}][CH_{3}NH_{3}^+]}{[CH_{3}NH_{2}]} <em>(1)</em>

In equilibrium, a solution of CH₃NH₂ 4,7M produces:

[CH₃NH₂] = 4,7 - x

[CH₃NH₃⁺] = x

[OH⁻] = x

Replacing in (1):

4,38x10^{-4} = \frac{x^2}{4,7-x}

x² + 4,38x10⁻⁴x - 2,0586x10⁻³ = 0

The solutions are:

x = -0,0456 No physical sense. There are not negative concentrations.

x = 0,04515 Real answer.

The concentration of [OH⁻] is 0,04515 M.

As pOH = -log [OH⁻] And pH+pOH = 14. The pH of this solution is:

<em>pH = 12,65</em>

The addition of 6,7M produce this changes in concentrations:

[CH₃NH₂] = 4,656 + x

[CH₃NH₃⁺] = 6,74515 - x

[OH⁻] = 0,04515 - x

Replacing in (1) you will obtain:

x² - 6,7907x + 0,3025 = 0

Solving for x:

x = 6,74586 No physical sense

x = 0,04484 Real answer.

Thus, [OH⁻] = 0,04515 - 0,044842 = 3,08x10⁻⁴M

pOH = 3,51.

<em>pH = 10,49</em>

Thus ΔpH is 12,65 - 10,49 = <em>2,16 ≈ 2,17</em>

I hope it helps!

You might be interested in
Name an object that the magnet would repel
Nataly_w [17]
The negative side of another magnet
3 0
3 years ago
A sample of oxalic acid (a diprotic acid of the formula H2C2O4) is dissolved in enough water to make 1.00 L of solution. A 100.0
OleMash [197]

<u>Answer:</u> The mass of original oxalic acid sample is 6.75 grams

<u>Explanation:</u>

To calculate the concentration of acid, we use the equation given by neutralization reaction:

n_1M_1V_1=n_2M_2V_2

where,

n_1,M_1\text{ and }V_1 are the n-factor, molarity and volume of acid which is H_2C_2O_4

n_2,M_2\text{ and }V_2 are the n-factor, molarity and volume of base which is NaOH.

We are given:

n_1=2\\M_1=?M\\V_1=100.0mL\\n_2=1\\M_2=0.750M\\V_2=20.0mL

Putting values in above equation, we get:

2\times M_1\times 100.0=1\times 0.750\times 20.0\\\\M_1=\frac{1\times 0.750\times 20.0}{2\times 100.0}=0.075M

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}

Given mass of oxalic acid = ? g

Molar mass of oxalic acid = 90 g/mol

Molarity of solution = 0.075 M

Volume of solution = 1.00 L

Putting values in above equation, we get:

0.075M=\frac{\text{Mass of oxalic acid}}{90g/mol\times 1L}\\\\\text{Mass of oxalic acid}=(0.075\times 90\times 1)=6.75g

Hence, the mass of original oxalic acid sample is 6.75 grams

7 0
3 years ago
A public School district furnishes pencils to its elementary school. The pencils the secretary orders from the district warehous
const2013 [10]

Answer:

The minimum number of boxes of pencils to be ordered is 630 boxes.

Explanation:

Since a pupil uses averagely 9.3 pencils

and a box contains 12 pencils,

the school enrollment is also 812

school's enrollment x average use of pencil per student

__________________________________________

            number of pencils in a box

812 x 9.3 = 7551.6

7551.6 /12 = 629.3

Having a total number of 630 boxes of pencils to be ordered.

3 0
2 years ago
A brand of dish soap says that it will get your dishes cleaner. What is the
vodka [1.7K]

Answer:

B

Explanation:

Si no demuestra que funciona te estarían estafando

3 0
2 years ago
4. a compound called pyrene has the empirical formula c8h5. when 4.04 g of pyrene is dissolved in 10.00 g of benzene, the boilin
e-lub [12.9K]

The molecular mass of pyrene is 204.4 g/mol.

From;

ΔT = Kb m i

Where;

  • ΔT = boiling point elevation
  • Kb = boiling point constant
  • m = molality
  • i = Van't Hoff factor

Since the compound is molecular; i = 1

The number of moles of pyrene = 4.04 g/MM

Where; MM = molar mass of pyrene

molality = number of moles of pyrene/mass of solvent in Kg

The mass of solvent = 10 g or 0.01 Kg

molality =  4.04 g/MM/0.01

ΔT = Boiling point of solution - Boiling point of pure solvent

ΔT = 85.1°C - 80.1°C

ΔT = 5°C

5 = 2.53 × 4.04 g/MM/0.01 × 1

5 = 10.22 × 1/0.01 MM

0.05MM = 10.22

MM= 10.22/0.05

MM= 204.4 g/mol

Learn more: brainly.com/question/2292439

3 0
2 years ago
Other questions:
  • Lithium, is used in dry cells and storage batteries and in high temperature lubricants, it has two naturally occurring isotopes,
    10·1 answer
  • Which of the following models represents a historical or modern model of the atom? a. The plum-pudding model. Selected:b. The pl
    10·1 answer
  • One mole of particles of any substance contains how many particles?
    5·1 answer
  • Reaccionan 54gr de Nitrato de plata al 39 % de pureza, con 72gr de ácido clorhídrico al 83% de pureza, en un proceso donde se ob
    15·1 answer
  • Balanced equations account for the conservation of mass? TRUE OR FALES??
    6·2 answers
  • Name three types of particles found in an atom and explain how they differ
    6·1 answer
  • C +02 → CO2 What type of chemical reaction is taking place in this
    12·1 answer
  • 1.- Ilumina de amarillo los verbos en pretérito y de verde los verbos en copretérito.
    8·1 answer
  • Write a balanced half-reaction for the reduction of bismuth oxide ion to bismuth ion in basic aqueous solution. Be sure to add p
    5·1 answer
  • Based on the name, which substance is a covalent compound?
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!