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anygoal [31]
3 years ago
10

A 29.2 mL sample of a 0.458 M aqueous hydrofluoric acid solution is titrated with a 0.337 M aqueous sodium hydroxide solution. W

hat is the pH at the start of the titration, before any sodium hydroxide has been added
Chemistry
1 answer:
Svetach [21]3 years ago
4 0

Answer:

3.51

Explanation:

Before any sodium hydroxide has been added, the pH is that of the aqueous hydrofluoric acid solution.

HF is a weak acid that dissociates according to the following equation.

HF(aq) ⇄ H⁺(aq) + F⁻(aq)      Ka = 6.76 × 10⁻⁴

We can find [H⁺] using the following expression.

[H⁺] = √(Ca × Ka)

where

Ca: concentration of the acid

Ka: acid dissociation constant

[H⁺] = √(Ca × Ka)

[H⁺] = √(0.458 × 6.76 × 10⁻⁴)

[H⁺] = 3.10 × 10⁻⁴ M

The pH is:

pH = -log [H⁺]

pH = -log 3.10 × 10⁻⁴ = 3.51

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Water was added to 175 mL of a KOH solution until the volume was 250 mL and the molarity was 0.315 M. What was the molarity of t
Len [333]

Answer:  The molarity of the initial concentrated solution is 0.450 M

Explanation:

According to the dilution law,

M_1V_1=M_2V_2

where,

M_1 = Molarity of concentrated KOH solution = ?

V_1 = volume of  concentrated KOH solution = 175 ml

C_2 = concentration of diluted KOH solution= 0.315 M

V_2 = volume of diluted KOH solution= 250 ml

Putting in the values, we get:

M_1\times 175=0.315\times 250

M_1=0.450M

Thus the molarity of the initial concentrated solution is 0.450 M

6 0
2 years ago
Sort the phrases based on whether they describe or give an example of diffusion, facilitated diffusion, both, or neither. note:
Bingel [31]

Question:

a. Diffusion

b. Facilitated diffusion

c. Both

d. Neither

1. movement to area of lower concentration

2. movement across a membrane

3. steroid transport into cell

4. requires energy

5. movement assisted by proteins

6. glucose transport into cell

   

Answer:

The sorting is as follows

a. (1)

b. (5 and 6)

c. (1 and 2)

d. (4)

Explanation:

Diffusion is the movement of particles across a membrane from a high concentration region to one with a lower concentration of the diffusing substance

Here we have the correct sorting as follows

a. Diffusion

3. steroid transport into cell

b. Facilitated diffusion

5. movement assisted by proteins

6. glucose transport into cell

c. Both

1. movement to area of lower concentration

2. movement across a membrane

d. Neither

4. requires energy

8 0
3 years ago
All of the following are units for pressure except _____. A. Pa B. psi C. atm D. Hg
MA_775_DIABLO [31]

Answer:

B. psi

Explanation:

Pa is Pascal

atm is atmosphere

Hg is Mercury

hope it helps.

6 0
3 years ago
if you could place a piece of solid silver into a container of liquid silver, would it float or sink? Explain your answer
olga55 [171]
Liquid silver is less dense than solid silver, so the solid silver would sink.
5 0
3 years ago
Read 2 more answers
How many miles of NaOH will completely react with 10.0 mL of 1.0 M HCl?
Naddik [55]
The reaction between 1 mole of NaOH and 1 mole of HCl creates 1 mole of NaCl and 1 mole of water. Meaning that the moles of HCl needs to equal that of NaOH for the solution to be considered equalized. That being said, you first need to find the numbers miles of HCl by multiplying the volume by the molarity to get 0.01 moles HCl. (1Mx0.01L=0.01). That means that you need 0.01 moles of NaOH. I hope that helps. Let me know if anything is unclear.
6 0
3 years ago
Read 2 more answers
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