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quester [9]
2 years ago
7

Someone please help me!! I'll give brainlest!

Chemistry
1 answer:
Trava [24]2 years ago
4 0

Answer:

Section Three

1. D

2. B

3. A

4. G

5. C

6. F

7. E

Section Four

1. F

2. E

3. B

4. A

5. C

6. D

7. G

Explanation:

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Glycolic acid, which is a monoprotic acid and a constituent in sugar cane, has a pKa of 3.9. A 25.0 mL solution of glycolic acid
Phoenix [80]

Answer:

pH = 8.0

Explanation:

First, we have to calculate the moles of NaOH.

35.8 \times 10^{-3}L.\frac{0.020mol}{L} =7.2\times 10^{-4}mol

Let's consider the balanced equation.

C₂H₄O₃ + NaOH ⇒ C₂H₃O₃Na + H₂O

The molar ratio C₂H₄O₃: NaOH: C₂H₃O₃Na is 1: 1: 1. So, when 7.2 × 10⁻⁴ moles of NaOH react completely with 7.2 × 10⁻⁴ moles of C₂H₄O₃ they form 7.2 × 10⁻⁴ moles of C₂H₃O₃Na.

The concentration of C₂H₃O₃Na is:

\frac{7.2\times 10^{-4}mol}{60.8 \times 10^{-3}L} =0.012M

C₂H₃O₃Na dissociates according to the following equation:

C₂H₃O₃Na(aq) ⇒ C₂H₃O₃⁻(aq) + Na⁺(aq)

C₂H₃O₃⁻ comes from a weak acid so it undergoes basic hydrolisis.

C₂H₃O₃⁻ + H₂O ⇄ C₂H₄O₃ + OH⁻

If we know that pKa for C₂H₄O₃ is 3.9, we can calculate pKb for C₂H₃O₃⁻ using the following expression:

pKa + pKb = 14

pKb = 14 -3.9 = 10.1

10.1 = -log Kb

Kb = 7.9 × 10⁻¹¹

We can calculate [OH⁻] using the following expression:

[OH⁻] = √(Kb.Cb)               <em>where Cb is the initial concentration of the base</em>

[OH⁻] = √(7.9 × 10⁻¹¹ × 0.012M) = 9.7 × 10⁻⁷ M

Now, we can calculate pOH and pH.

pOH = -log [OH⁻] = -log (9.7 × 10⁻⁷) = 6.0

pH + pOH = 14

pH = 14 - pOH = 14 - 6.0 = 8.0

7 0
3 years ago
Boron sulfide, B2S3(s), reacts violently with water to form dissolved boric acid (H3BO3) and hydrogen sulfide gas.Express your a
ioda

Answer:

Explanation:

From the statement of the problem,

  B₂S₃_{s} + H₂O_{l}  →  H₃BO₃_{aq} + H₂S_{g}

              B₂S₃ + H₂O  →  H₃BO₃ + H₂S

We that the above expression does not conform with the law of conservation of mass:

To obey the law, we need to derive a balanced reaction equation:

   Let us use the mathematical method to obtain a balanced equation.

let the balanced equation be:

                        aB₂S₃ + bH₂O  →  cH₃BO₃ + dH₂S

where a, b, c and d will make the equation balanced.

  Conservating B: 2a = c

                          S: 3a = d

                          H: 2b = 3c + 2d

                           O: b = 3c

   if a = 1,

      c = 2,

      b = 6,

      2d = 2(6) - 3(2) = 6, d = 3

Now we can input this into our equation:

                     B₂S₃ + 6H₂O  →  2H₃BO₃ + 3H₂S

    B₂S₃_{s} + 6H₂O_{l}  →  2H₃BO₃_{aq} + 3H₂S_{g}

4 0
3 years ago
How to calculate the frequency of an ion
sergij07 [2.7K]

solution:

You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. (1 nm = 1.0 x 10^{-9} m)

v=c\lambda \\v= (3.00 \times 10^8 m/s)/(6.9\times 10^-7 m) \\v = 4.35 \times 10^{14} s^{-1}

8 0
3 years ago
How many atoms are there in 4.13 moles of nickel (Ni)
PtichkaEL [24]

Answer:

24.87× 10²³ atoms of Ni

Explanation:

Given data:

Number of atoms of Ni= ?

Number of moles of Ni = 4.13 mol

Solution:

we will calculate the number of atoms of Ni by using  Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms

4.13 mol ×  6.022 × 10²³ atoms /1 mol

24.87× 10²³ atoms of Ni

6 0
3 years ago
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