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iris [78.8K]
3 years ago
13

A buffer solution contains 0.345 M acetic acid and 0.377 M sodium acetate . If 0.0613 moles of potassium hydroxide are added to

250 mL of this buffer, what is the pH of the resulting solution ? (Assume that the volume does not change upon adding potassium hydroxide. )
Chemistry
1 answer:
melamori03 [73]3 years ago
6 0

Answer:

pH = 5.54

Explanation:

The pH of a buffer solution is given by the <em>Henderson-Hasselbach (H-H) equation</em>:

  • pH = pKa + log\frac{[CH_3COO^-]}{[CH_3COOH]}

For acetic acid, pKa = 4.75.

We <u>calculate the original number of moles for acetic acid and acetate</u>, using the <em>given concentrations and volume</em>:

  • CH₃COO⁻ ⇒ 0.377 M * 0.250 L = 0.0942 mol CH₃COO⁻
  • CH₃COOH ⇒ 0.345 M * 0.250 L = 0.0862 mol CH₃COOH

The number of CH₃COO⁻ moles will increase with the added moles of KOH while the number of CH₃COOH moles will decrease by the same amount.

Now we use the H-H equation to <u>calculate the new pH</u>, by using the <em>new concentrations</em>:

  • pH = 4.75 + log\frac{(0.0942+0.0613)mol/0.250L}{(0.0862-0.0613)mol/0.250L} = 5.54
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Rank the solutions in order of decreasing [H3O ]. Rank solutions from largest to smallest hydronium ion concentration. To rank i
Usimov [2.4K]

Answer:

0.10M HCN  <  0.10 M HClO  <  0.10 M HNO₂  < 0.10 M HNO₃

Explanation:

We are comparing acids with the same concentration. So what we have to do first is to determine if we have any strong acid and for the rest ( weak acids ) compare them by their Ka´s ( look for them in reference tables ) since we know the larger the Ka, the more Hydronium concentration will be in these solutions at the same concentration.

HNO₃ is a strong acid and will have the largest hydronium concentration.

HCN  Ka = 6.2 x 10⁻¹⁰

HNO₂ Ka = 4.0 x 10⁻⁴

HClO  Ka = 3.0 x 10⁻⁸

The ranking from smallest to largest hydronium concentration will then be:

0.10M HCN  <  0.10 M HClO  <  0.10 M HNO₂  < 0.10 M HNO₃

5 0
3 years ago
1. A chemical bond between metals and nonmetals; valence electrons are transferred ____.
Law Incorporation [45]

Answer:

1. Ionic bonding

2. Covalent bonding

3. Metallic bonding

Explanation:

Ionic bonding also referred to as electrovalent bonding is a kind of chemical bonding that involves the transfer of electrons between the valence shells of two elements with a large electronegativity difference usually a metal and a nonmetal.

For example an ionic bonding scenario might play out between a group one metal and a group seven halogen. While group one metals have one electron hindering their stability, group seven halogens need that one electron that could make them achieve this stability. It is this that causes them to come together in a way where the electron is transferred completely from the valence shell of the group 1 atom and accepted into the valence shell of the group 7 halogen.

Covalent bonding involves the sharing of electrons between atoms of comparable electronegativities. The electro negativity difference is not large enough to permit the total movement of the electrons and hence the electrons are then controlled by the nuclei of the two atoms

Between two metals, what we have is called the metallic bonding

7 0
3 years ago
Methane burns in the presence of oxygen to form carbon dioxide and water.
wlad13 [49]

Answer:

= 9.28 g CO₂

Explanation:

First write a balanced equation:

CH₄ + 2O₂ -> 2H₂O + CO₂

Convert the information to moles

7.50g CH₄ = 0.46875 mol CH₄

13.5g O₂ = 0.421875 mol O₂

Theoretical molar ratio CH₄:O₂ -> 1:2

Actual ratio is  0.46875 : 0.421875 ≈ 1:1

If all CH₄ is used up, there would need to be more O₂

So O₂ is the limiting reactant and we use this in our equation

Use molar ratio to find moles of CO₂

0.421875 mol O₂ * 1 mol CO₂/2 mol O₂=0.2109375 mol CO₂

Then convert to grams

0.2109375 mol CO₂ = 9.28114 g CO₂

round to 3 sig figs

= 9.28 g CO₂

5 0
3 years ago
(d) carbon monoxide
Irina18 [472]

Answer:

D. carbon monoxide

Hope this helps :)

6 0
2 years ago
Who knows this........​
kvv77 [185]

Answer:

D

Explanation:

This creates a gap that we call an oceanic trench

:)

4 0
2 years ago
Read 2 more answers
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