This is a difficult task because zinc is much more active than copper and could hardly be passivated. ... The sur- face immediately turns white (the color of copper(I) iodide) and the yellow-brown color of iodine quickly fades. Rinse the coin with water, brighten it with polish and cloth and begin the whole process again.N
2.083 Liters of 6.0 M solution sulfuric acid is required. This solved using molecular calculations and Titration.
Solution: 
Moles of hydrogen gas = 
Then 12.5 moles of hydrogen will be obtained from Moles of Sulfuric acid = 12.5 mol
Molarity of the sulfuric acid solution = 6.0 M = 6 mol/ l
6M = 
where V is the volume needed

V = 2.083 l
<h3>
What is Titration?</h3>
- Titration, commonly referred to as titrimetry, is a typical quantitative chemical analysis method used in laboratories to ascertain the unidentified quantity of an analyte .
- Titration is frequently referred to as volumetric analysis because it relies heavily on volume measurements. The titrant or titrator is a reagent that is prepared as a standard solution.
- To determine concentration, a solution of the analyte or titrand reacts with a known concentration and volume of the titrant. The titration volume is the amount of titrant that has responded.
- Titrations come in a variety of forms with various protocols and objectives. Redox and acid-base titrations are the two most typical types of qualitative titrations.
To learn more about titration with the given link
brainly.com/question/2728613
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Answer : The correct option is, +91 kJ/mole
Solution :
The balanced cell reaction will be,

Here copper (Cu) undergoes oxidation by loss of electrons, thus act as anode. Lead (Pb) undergoes reduction by gain of electrons and thus act as cathode.
First we have to calculate the standard electrode potential of the cell.
![E^0_{[Pb^{2+}/Pb]}=-0.13V](https://tex.z-dn.net/?f=E%5E0_%7B%5BPb%5E%7B2%2B%7D%2FPb%5D%7D%3D-0.13V)
![E^0_{[Cu^{2+}/Cu]}=+0.34V](https://tex.z-dn.net/?f=E%5E0_%7B%5BCu%5E%7B2%2B%7D%2FCu%5D%7D%3D%2B0.34V)

![E^0_{cell}=E^0_{[Pb^{2+}/Pb]}-E^0_{[Cu^{2+}/Cu]}](https://tex.z-dn.net/?f=E%5E0_%7Bcell%7D%3DE%5E0_%7B%5BPb%5E%7B2%2B%7D%2FPb%5D%7D-E%5E0_%7B%5BCu%5E%7B2%2B%7D%2FCu%5D%7D)

Now we have to calculate the standard Gibbs free energy.
Formula used :

where,
= standard Gibbs free energy = ?
n = number of electrons = 2
F = Faraday constant = 96500 C/mole
= standard e.m.f of cell = -0.47 V
Now put all the given values in this formula, we get the Gibbs free energy.

Therefore, the standard Gibbs free energy is +91 kJ/mole
Answer:
0.297 mol/L
Explanation:
<em>A chemist prepares a solution of potassium dichromate by measuring out 13.1 g of potassium dichromate into a 150 mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mol/L of the chemist's potassium dichromate solution. Be sure your answer has the correct number of significant digits.</em>
<em />
Step 1: Calculate the moles corresponding to 13.1 g of potassium dichromate
The molar mass of potassium dichromate is 294.19 g/mol.
13.1 g × (1 mol/294.19 g) = 0.0445 mol
Step 2: Convert the volume of solution to L
We will use the relationship 1 L = 1000 mL.
150 mL × (1 L/1000 mL) = 0.150 L
Step 3: Calculate the concentration of the solution in mol/L
C = 0.0445 mol/0.150 L = 0.297 mol/L