Answer:
1 gram
Explanation:
1 gram= weight of 1 cubic centimeter of pure water at temperature 4°C = 1000 milligrams = 0.001 kilogram
Answer:
0.387 g
Explanation:
pH of the buffer = 1
V = Volume of solution = 100 mL
[HA] = Molarity of HA = 0.1 M
= Acid dissociation constant = 
(assuming base as 
)
Molar mass of base = 322.2 g/mol
pKa is given by
From the Henderson-Hasselbalch equation we get
![pH=pK_a+\log\dfrac{[A^-]}{[HA]}\\\Rightarrow pH-pK_a=\log\dfrac{[A^-]}{[HA]}\\\Rightarrow 10^{pH-pK_a}=\dfrac{[A^-]}{[HA]}\\\Rightarrow [A^-]=10^{pH-pK_a}[HA]\\\Rightarrow [A^-]=10^{1-1.92}\times0.1\\\Rightarrow [A^-]=0.01202\ \text{M}](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%5Cdfrac%7B%5BA%5E-%5D%7D%7B%5BHA%5D%7D%5C%5C%5CRightarrow%20pH-pK_a%3D%5Clog%5Cdfrac%7B%5BA%5E-%5D%7D%7B%5BHA%5D%7D%5C%5C%5CRightarrow%2010%5E%7BpH-pK_a%7D%3D%5Cdfrac%7B%5BA%5E-%5D%7D%7B%5BHA%5D%7D%5C%5C%5CRightarrow%20%5BA%5E-%5D%3D10%5E%7BpH-pK_a%7D%5BHA%5D%5C%5C%5CRightarrow%20%5BA%5E-%5D%3D10%5E%7B1-1.92%7D%5Ctimes0.1%5C%5C%5CRightarrow%20%5BA%5E-%5D%3D0.01202%5C%20%5Ctext%7BM%7D)
Moles of base
Mass of base is given by
The required mass of the base is 0.387 g.
Before<span> the </span>eruption,the fluid pressure from the rising magma (dense liquid) cracks the rocks, the tectonic plates under the Earth's crust are moved and as a result, earthquakes<span> are </span>caused<span>. A lot of </span>small earthquakes<span> in the area near a </span>volcano<span> hint what may </span>happen<span>.</span>
Answer:
D. Ni²⁺
Explanation:
We know at once that the answer cannot be A or C, because Ni and Cu are already in their lowest oxidation states.
The correct answer must be either B or D.
An electrolytic cell is the opposite of a galvanic cell. In the former, the reaction proceeds spontaneously. In the latter, you must force the reaction to occur.
One strategy to solve this problem is:
- Look up the standard reduction potentials for the half reaction·
- Figure out the spontaneous direction.
- Write the equation in the reverse direction.
1. Standard reduction potentials
E°/V
Cu²⁺ + 2e⁻ ⟶ Cu; 0.3419
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
2. Galvanic Cell
We reverse the direction of the more negative half cell and add.
<u>E°/V
</u>
Ni ⟶ Ni²⁺ + 2e⁻; 0.257
<u>Cu²⁺ + 2e⁻ ⟶ Cu; </u> 0.3419
Ni + Cu²⁺ ⟶ Cu + Ni²⁺; 0.599
This is the spontaneous direction.
Cu²⁺ is reduced to Cu.
3. Electrochemical cell
<u>E°/V</u>
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
<u>Cu ⟶ Cu²⁺ + 2e⁻; </u> <u>-0.3419</u>
Cu + Ni²⁺ ⟶ Ni + Cu²⁺; -0.599
This is the non-spontaneous direction.
Ni²⁺ is reduced to Ni in the electrolytic cell.
