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Nady [450]
3 years ago
7

Calculate the pH of a solution that is 0.210 M in nitrous acid (HNO2) and 0.290 M in potassium nitrite (KNO2). The acid dissocia

tion constant of nitrous acid is 4.50 × 10-4.
Chemistry
1 answer:
jeka943 years ago
6 0

Answer:

pH = 3.49

Explanation:

We have a buffer system formed by a weak acid (HNO₂) and its conjugate base (NO₂⁻ coming from KNO₂). We can calculate the pH  of a buffer ssytem using the Henderson-Hasselbach equation.

pH = pKa + log [base] / [acid]

pH = -log Ka + log [NO₂⁻] / [HNO₂]

pH = -log 4.50 × 10⁻⁴ + log 0.290 M / 0.210 M

pH = 3.49

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Why does thermal energy decreases when potassium is dissolved in water​
Levart [38]

Answer:

The process of dissolving can be endothermic (temperature goes down) or exothermic (temperature goes up).

When water dissolves a substance, the water molecules attract and “bond” to the particles (molecules or ions) of the substance causing the particles to separate from each other.

The “bond” that a water molecule makes is not a covalent or ionic bond. It is a strong attraction caused by water’s polarity.

It takes energy to break the bonds between the molecules or ions of the solute.

Energy is released when water molecules bond to the solute molecules or ions.

If it takes more energy to separate the particles of the solute than is released when the water molecules bond to the particles, then the temperature goes down (endothermic).

If it takes less energy to separate the particles of the solute than is released when the water molecules bond to the particles, then the temperature goes up (exothermic).

Explanation:

8 0
3 years ago
An electrochemical cell is constructed using two half-cells: Al(s) in Al(NO2)3(aq) and Cu(s) in Cu(NO3)2(aq). The two half cells
wlad13 [49]

Answer:

Cu(s) in Cu(NO₃)₂(aq)

Explanation:

The standard reduction potential (E°) is the energy necessary to reduce the atom in a redox reaction. When an atom reduces it gains electrons from other than oxides. As higher is E°, easily it will reduce. The substance that reduces is at the cathode of a cell, where the electrons go to, and the other that oxides are at the anode of the cell.

The standard reduction potentials from Al(s) and Cu(s) are, respectively, -1.66V and +0.15V, so the half-cell of Cu(s) in Cu(NO₃)₂(aq) is the cathode.

4 0
3 years ago
In a chemical equation, which symbol should be used to indicate that a substance is in solution?
lisov135 [29]
Example :

2FeCl_3_{(aq)}+2KI_{(aq)}=2FeCl2_{(aq)}+2KCl_{(aq)}+I_2_{(s)}

If you use the subscript (aq) (=aquaris) , this means that the substance is in a solution.

Subscripts:
-aq-this means that the substance is in a solution
-s-this means that the substance is a solid(or precipitate)
-l-this means that the substance is a liquid
-g-this means that the subtance is a gas

6 0
3 years ago
Read 2 more answers
Just need help with these two questions
kvasek [131]
B/A hope it help thanks
8 0
2 years ago
What is hydrogen ion concentration of an acid solution whose PH is 3.4?​
meriva
It’s easy, if the PH of any acidic solution = -Log[H+], where [H+] is hydrogen ion concentration, multiply each term by (-1) then raise each term as a power to (10), so it will become like this:-
[H+] = 10^(-PH)
4 0
2 years ago
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