Answer:
75 mg
Explanation:
We can write the extraction formula as
x = m/[1 + (1/K)(Vaq/Vo)], where
x = mass extracted
m = total mass of solute
K = distribution coefficient
Vo = volume of organic layer
Vaq = volume of aqueous layer
Data:
m = 75 mg
K = 1.8
Vo = 0.90 mL
Vaq = 1.00 mL
Calculations:
For each extraction,
1 + (1/K)(Vaq/Vo) = 1 + (1/1.8)(1.00/0.90) = 1 + 0.62 = 1.62
x = m/1.62 = 0.618m
So, 61.8 % of the solute is extracted in each step.
In other words, 38.2 % of the solute remains.
Let r = the amount remaining after n extractions. Then
r = m(0.382)^n.
If n = 7,
r = 75(0.382)^7 = 75 × 0.001 18 = 0.088 mg
m = 75 - 0.088 = 75 mg
After seven extractions, 75 mg (99.999 %) of the solute will be extracted.
Atoms are electrically neutral because the number of protons, which carry a 1+ charge, in the nucleus of an atom is equal to the number of electrons, which carry a 1- charge, in the atom. The result is that the total positive charge of the protons cancels out the total negative charge of the electrons so that the net charge of the atom is zero. Most atoms, however, can either gain or lose electrons; when they do so, the number of electrons becomes different from the number of protons in the nucleus. The resulting charged species is called an ion.
Rechargeable batteries use a reversible reaction medium to convert electrical current to a form of chemical energy which can be stored for future use.
<h3>
What is a rechargeable battery?</h3>
A rechargeable battery is a type of battery that can be charged many times by passing electric current through the cells in a reversible reaction.
<h3>How does recahargeable battery store energy?</h3>
When electrical energy from an outside source is applied to a secondary cell (reachargeable battery), the negative to positive electron flow that occurs during discharge is reversed, and the cell's charge is restored. This process is called reversible reaction.
Thus, rechargeable batteries use a reversible reaction medium to convert electrical current to a form of chemical energy which can be stored for future use.
Learn more about reversible reaction here: brainly.com/question/11412193
Answer:
[HAc] = 0.05M
[Ac⁻] = 0.20M
Explanation:
The Henderson-Hasselbalch formula for the acetic acid buffer is:
pH = pka + log₁₀ [Ac⁻] / [HAc]
Replacing:
5.36 = 4.76 + log₁₀ [Ac⁻] / [HAc]
3.981 = [Ac⁻] / [HAc] <em>(1)</em>
Also, as total concentration of buffer is 0.25M it is possible to write:
0.25M = [Ac⁻] + [HAc] <em>(2)</em>
Replacing (2) in (1)
3.981 = 0.25M - [HAc] / [HAc]
3.981 [HAc] = 0.25M - [HAc]
4.981 [HAc] = 0.25M
<em>[HAc] = 0.05M</em>
Replacing this value in (2):
0.25M = [Ac⁻] + 0.05M
<em>[Ac⁻] = 0.20M</em>
I hope it helps!
