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
Novosadov [1.4K]
3 years ago
5

Suppose that you have 125 mL of a buffer that is 0.140 M in both hydrofluoric acid ( HF ) and its conjugate base ( F − ) . Calcu

late the maximum volume of 0.370 M HCl that can be added to the buffer before its buffering capacity is lost.
Chemistry
1 answer:
pshichka [43]3 years ago
8 0

Answer:

38,7mL of HCl 0,370M

Explanation:

The buffering capacity is lost when the pH of the solution is out of pka ± 1.

For the buffer:

HF ⇄ H⁺ + F⁻; pka = 3,20

Moles of both HF and F⁻ are:

HF: 0,140M ₓ 0,125L = 0,0175 moles of HF

Moles of F⁻ are the same.

Using Henderson-Hasselbalch formula:

pH = pka + log₁₀ F⁻ / HF

pH = 3,20 + log F⁻ / HF <em>(1)</em>

The addition of X moles of HCl (H⁺) shift the equilibrium to the left, thus:

         HF             ⇄   H⁺  +     F⁻

0,0175 moles + X             0,0175 moles - X          

The buffer lost its capacity when pH = 3,20 - 1 = 2,20. Thus, replacing in (1):

2,20 = 3,20 + log ₁₀0,0175 - X / 0,0175 + X

0,1 = 0,0175 - X / 0,0175 + X

0,00175 + 0,1X = 0,0175 - X

-0,01575 = -1,1X

<em>0,0143 moles = X</em>

You need to add 0,0143 moles of HCl. In volume for a concentration of 0,370M HCl:

0,0143 moles ÷ 0,370M = 0,0387L of HCl 0,370M ≡ <em>38,7mL of HCl 0,370M</em>

I hope it helps!

You might be interested in
Trimix 10/50 is a gas mixture that contians 10% oxygen and 50% helium, and the rest is nitrogen. If a tank of trimix 10/50 has a
Nataly_w [17]

Answer: 1.61 x 10⁴ kPa

Dalton's law <u>states that the sum of the partial pressures of each gas equals the total pressure of the gas mixture.</u> According to this law,

Pi = xi P

where Pi is the partial pressure of the gas i, xi is the mole fraction of the gas i in the gas mixture and P is the total pressure.

The mole fraction <u>is defined as the quotient between the moles of solute (ni) and the total moles of the mixture (nt)</u>, which is calculated by adding the moles of all its components:

xi = \frac{n_{i} }{n_{t} }

In the Trimix 10/50 mix you have 10% oxygen, 50% helium and 40% nitrogen.

To calculate the total number of moles of the mixture and thus determine the molar fraction of helium, we consider 100 g and calculate the number of moles that represent 10 g of O₂ (n₁), 50 g of He (n₂) and 40 g of N₂ (n₃):

n₁ =  10 g x \frac{1 mol}{31.998 g} = 0.313 mol

n₂ =  50 g x \frac{1 mol}{8.005 g} = 6.246 mol

n₃ =  40 g x \frac{1 mol}{28.013 g} = 1.428 mol

Then the total number of moles (nt) will be:

nt = n₁ + n₂ + n₃ = 0.313 mol + 6.246 mol +1.428 mol

nt = 7,987 mol

Then, the mole fraction of helium (x₂) in the mixture will be,

x₂ =  \frac{6.246 mol}{7.987 mol} = 0.78

and the partial pressure of helium in the mixture, according to Dalton's law, will be:

P₂ = x₂ P = 0.78 x 2.07 x 10⁴ kPa

P₂= 1.61 x 10⁴ kPa

So, <u>the partial pressure of helium if a tank of trimix 10/50 has a total pressure of 2.07 x 104 kPa is  1.61 x 10⁴ kPa</u>

5 0
3 years ago
hello my BEANS i want to know if u r a girl or a boy so if i call u a boy and u r a girl i am not a bad person i am 13 and i am
finlep [7]

Answer:

okie

Explanation:

imma girl

4 0
3 years ago
Read 2 more answers
Potassium-40 (40k) is a radioactive isotope of potassium (atomic number 19). how many neutrons are located in the nucleus of pot
sineoko [7]
Number of neutrons  = mass number - atomic number = 40 - 19 = 21 answer
6 0
3 years ago
Which is a renewable energy source?
Likurg_2 [28]

Answer:

The answer is D. Hydroelectric

4 0
3 years ago
Read 2 more answers
What’s the difference between heterogeneous and homogeneous mixtures?
Ronch [10]

Answer:

Mixtures can be either homogeneous or heterogeneous. A mixture in which its constituents are distributed uniformly is called homogeneous mixture, such as salt in water. A mixture in which its constituents are not distributed uniformly is called heterogeneous mixture, such as sand in water.

5 0
3 years ago
Other questions:
  • Which statements correctly describe atmospheric pressure?
    7·1 answer
  • Is glucose a solution colloid or suspension?
    7·1 answer
  • Which of the following elements is a metalloid
    11·2 answers
  • Name the following ionic compound KBr
    6·1 answer
  • All matter has __. A.) COLOR B.) MASS C.) VOLUME D.) WEIGHT
    12·1 answer
  • A sample of 14.5 g of sodium bicarbonate (NaHCO3) was dissolved in 100 ml of water in a coffee-cup calorimeter with no lid by th
    9·1 answer
  • What is the relationship between the sequence of DNA’s subcomponents and the properties of DNA? 1. The amino acid sequence along
    8·1 answer
  • How many grams of glyoxylic acid and sodium glyoxylate are needed to prepare 2.50 L of a 1.60 M buffer at pH 3.85? The pKa of gl
    8·1 answer
  • Can you think of 2 renewable resources and 2 nonrenewable resources
    6·2 answers
  • recall that temperature is a measure of the average kinetic energy of a substance. both ethanol and water had the same amount of
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!