The Nernst equation is:
E = E° - RTlnK/nF
where
E° is the standard potential voltage
R is the universal gas constant = 8.314 J/mol·K
K is the reaction quotient
n is the number of moles electrons transferred
F is Faraday's constant = 96,500 C/mol e⁻
Let's determine K first. The overall reaction is:
Fe(s) + Cd²⁺(aq) --> Fe²⁺(aq) + Cd(s)
Accounting for aqueous phases only,
K = [products]/[reactants] = [Fe²⁺]/[Cd²⁺] = 0.10 M/1.4 M = 1/14
From the reactions written, you can see that 2 electrons were transferred. So, n = 2.
Lastly, the value for E⁰ is the sum of individual E⁰ of the reactions.
E⁰ = E⁰cathode - E⁰anode
Cathode reaction: Fe(s) --> 2e + Fe²⁺ (E⁰cathode = 0.44 V)
Anode reaction: Cd²⁺ + 2e --> Cd(s) (E⁰anode = -0.4 V)
Thus,
E⁰ = 0.44 - -0.4 = 0.84 V
Substituting the values (assume T at room temperature = 298 K),
E = 0.84 - (8.314)(298 K)(ln 1/14)/(2)(96,500)
<em>E = 0.87 V</em>
Answer:
No.
Explanation:
This is because a solution is a mixture with two substances that have already dissolved in each other and so there is no residue left. Filtration works such that part of the mixture has smaller particles that can pass through the membrane of the filter paper while the bigger particles get stuck onto the paper as residue. A solution has a uniform size particle throughout and thus filtration does not work for purifying a solution.
Answer:
15.33
Explanation:
Given parameters:
Mass of KOH = 121g
Volume of solution = 100mL = 0.1dm³
Molar mass of KOH = 56.11g/mol
Unknown:
pH of the solution = ?
Solution:
To find the pH, we must first know the concentration of the solution obtained by mixing KOH up to this volume.
This can be done by finding the molarity of the solution.
Molarity =
Number of moles of KOH = = = 2.16mole
Input parameters;
Molarity of solution = = 21.6moldm⁻³
KOH → OH⁻ + K⁺
21.6 21.6 21.6
In the solution we have 21.6moldm⁻³ of OH⁻ which is need to find the pH;
pOH = -log₁₀(OH⁻)
pOH = -log₁₀21.6
pOH = -1.33
Since pH + pOH = 14
pH = 14 - (-1.33) = 15.33