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Pj Problems - Overview

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COHN - Natures Engineering Of The Human Body

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Painting

Nernst Cell Voltage Equation

Given the following Daniell cell (a typical voltaic or galvanic cell):

Zn|Zn^{2+}||Cu^{2+}|Cu

Determine the cell voltage (potential) at 25^{o}C If the concentrations of the zinc ions and the copper ions are 0.50m and 0.20m respectively.

**The strings**:

S_{7}P_{5}A_{52} (Change - Chemical Change)
**The math**:

Pj Problem of Interest is of type *change* (chemical change). This problem is also a *force* problem because we are determining voltage which is *force* (push). However, the Pj Problem of Interest is cast as of type *change* because of the underlying chemical reaction that made the cell voltage possible.

This problem is solved using Nernst equation:

Cell voltage, E = E^{o} - (RT/nF)lnK

where K = equilibrium constant = concentration of products/concentration of reactants.

The half-reactions of the cell are as follows:

Half-reaction at the anode:

Zn -------> Zn^{2+} + 2e^{-} --------(1) oxidation reaction.

Standard reduction potential from table = - 0.762 volts

Since this half-reaction is an oxidation reaction, we change -0.762 to +0.762.

Half-reaction at the cathode:

Cu^{2+} + 2e^{-} -------> Cu -------(2) reduction reaction

Standard reduction potential from table = 0.340

Since this half-reaction is a reduction reaction, we do not need to change table value.

Overall cell reaction

Zn(c) + Cu^{2+}(aq) --------> Zn^{2+}(aq) + Cu(c)---------(3)

So, E^{o} = 0.762 + 0.340 = 1.102 volts.

Since concentrations are not standard (1M), we use the Nernst equation.

So, E = 1.102 - (8.31)(298)/2(96485)ln(0.50/0.20)

So, cell voltage, E = 1.102 - (0.01284)ln2.5 = 1.088 volts.

Math

The *point* **.** is a mathematical abstraction. It has negligible size and a great sense of position. Consequently, it is front and center in abstract existential reasoning.

Derivation Of The Area Of A Circle, A Sector Of A Circle And A Circular Ring

Derivation Of The Area Of A Trapezoid, A Rectangle And A Triangle

Derivation Of The Area Of An Ellipse

Derivation Of Volume Of A Cylinder

Derivation Of Volume Of A Sphere

Derivation Of Volume Of A Cone

Derivation Of Volume Of A Torus

Derivation Of Volume Of A Paraboloid

Single Variable Functions

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Equation Of The Ascent Path Of An Airplane

Calculating Capacity Of A Video Adapter Board Memory

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Advanced Calculus - Partial Derivatives

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Advanced Calculus - Multiple Integrals

Production Schedule That Maximizes Profit Given Constraint Equation

Separation Of Variables As Solution Method For Homogeneous Heat Flow Equation

Newton And Fourier Cooling Laws Applied To Heat Flow Boundary Conditions

Fourier Series

Derivation Of Heat Equation For A One-Dimensional Heat Flow

Homogenizing-Non-Homogeneous-Time-Varying-IBVP-Boundary-Condition

The Universe is composed of *matter* and *radiant energy*. *Matter* is any kind of *mass-energy* that moves with velocities less than the velocity of light. *Radiant energy* is any kind of *mass-energy* that moves with the velocity of light.

Periodic Table

Composition And Structure Of Matter

How Matter Gets Composed

How Matter Gets Composed (2)

Molecular Structure Of Matter

Molecular Shapes: Bond Length, Bond Angle

Molecular Shapes: Valence Shell Electron Pair Repulsion

Molecular Shapes: Orbital Hybridization

Molecular Shapes: Sigma Bonds Pi Bonds

Molecular Shapes: Non ABn Molecules

Molecular Orbital Theory

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