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  2. Taft equation - Wikipedia

    en.wikipedia.org/wiki/Taft_equation

    where ⁡ is the ratio of the rate of the substituted reaction compared to the reference reaction, ρ* is the sensitivity factor for the reaction to polar effects, σ* is the polar substituent constant that describes the field and inductive effects of the substituent, δ is the sensitivity factor for the reaction to steric effects, and E s is ...

  3. Power factor - Wikipedia

    en.wikipedia.org/wiki/Power_factor

    The power factor in a single-phase circuit (or balanced three-phase circuit) can be measured with the wattmeter-ammeter-voltmeter method, where the power in watts is divided by the product of measured voltage and current. The power factor of a balanced polyphase circuit is the same as that of any phase. The power factor of an unbalanced ...

  4. Induction generator - Wikipedia

    en.wikipedia.org/wiki/Induction_generator

    Power factor correcting capacitors can be added externally to neutralize a constant amount of the variable reactive excitation current. After starting, an induction generator can use a capacitor bank to produce reactive excitation current, but the isolated power system's voltage and frequency are not self-regulating and destabilize readily.

  5. Leading and lagging current - Wikipedia

    en.wikipedia.org/wiki/Leading_and_Lagging_Current

    Angle notation can easily describe leading and lagging current: . [1] In this equation, the value of theta is the important factor for leading and lagging current. As mentioned in the introduction above, leading or lagging current represents a time shift between the current and voltage sine curves, which is represented by the angle by which the curve is ahead or behind of where it would be ...

  6. List of unsolved problems in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    RNA folding problem: Is it possible to accurately predict the secondary, tertiary and quaternary structure of a polyribonucleic acid sequence based on its sequence and environment? Protein design : Is it possible to design highly active enzymes de novo for any desired reaction?

  7. Steric effects - Wikipedia

    en.wikipedia.org/wiki/Steric_effects

    In organic chemistry, steric effects are nearly universal and affect the rates and activation energies of most chemical reactions to varying degrees. In biochemistry, steric effects are often exploited in naturally occurring molecules such as enzymes , where the catalytic site may be buried within a large protein structure.

  8. Kinetic isotope effect - Wikipedia

    en.wikipedia.org/wiki/Kinetic_isotope_effect

    In physical organic chemistry, a kinetic isotope effect (KIE) is the change in the reaction rate of a chemical reaction when one of the atoms in the reactants is replaced by one of its isotopes. [3] Formally, it is the ratio of rate constants for the reactions involving the light ( k L ) and the heavy ( k H ) isotopically substituted reactants ...

  9. Inductive effect - Wikipedia

    en.wikipedia.org/wiki/Inductive_effect

    The effect of the sigma electron displacement towards the more electronegative atom by which one end becomes positively charged and the other end negatively charged is known as the inductive effect. The -I effect is a permanent effect & generally represented by an arrow on the bond. [citation needed]