This is a pico hydro power system. The motor output is 4.5 kW.
Tag Archives: delta
How can I convert a 3 phase 415 Volt delta induction motor to 3 phase 240 Volts delta?
Tagged delta, hydro, hydro power, induction, induction motor, motor, phase, pico, pico hydro, power, system, volt, volt delta, volts
Free energy and equilibrium constant K?
I am confused about why delta G (DG) = 0 when a system is at equilibrium. I know DG=0 because of the equation DG = -RTlnK and K=1. However, I thought K is a constant that is specific to any reaction, and when something is in equilibrium Q=K, and K doesn’t have to be 1 (in fact, K usually is never 1, but instead, something very small or big, like 6×10^-5 or 7×10^2). So, if a reaction is at equilibrium (a reaction with an eq. constant K that is NOT equal to 1), then DG will not equal to 0. If this is true, then I don’t understand why the textbook tells me DG = 0 when the system is at equilibrium, with K = 1. (I don’t understand why K has to be 1 at equilibrium, since K is a constant that can be any number) Please explain. Thanks.
Posted in Solar Power
Tagged delta, dg, energy, eq, equation, equilibrium, fact, free energy, NOT, reaction, RTlnK, something, system, textbook
Tabulated values of chemical thermodynamic properties seem inconsistent. What am I misunderstanding?
The table in the back of my wife’s chemistry textbook tabulates values of the standard enthalpy of formation delta-Hf0, the standard entropy S0, and the standard free energy of formation delta-Gf0, for a wide variety of elements and compounds, all evaluated at 25C. As I understand it, they should be connected by the relationship
delta-Gf0 = delta-Hf0 – T*S0
They aren’t. For instance, for liquid water, it gave
delta-Hf0 = -286 kJ/mole
S0 = 69.96 J/(mole K)
delta-Gf0 = -237.2 kJ/mole
25C corresponds to T = 298.16 K , so by my calculations detla-Gf0 should be
-286 kJ/mole – 298.16 K * (69.96 J/(mole K) / 1000 (kJ/J)) = -307 kJ/mole
None of the entries in the table work out as I expected, which rules out a typo. I’ve checked with other sources, and they all agree tolerably well with the values tabulated in this textbook. What am I misunderstanding?
Chemistry: Equilibrium Questions?
Calculate the equilibrium constant for the following reaction at 80 degrees Celcius. Also, Delta G(final (not)), the standard free energy of formation for Ni(CO)4 (g) = -587.4 kJ/mol. Assume that Delta G (final (not)) is temperature independent.
Ni(s) + 4CO (g) —> <—– Ni(CO)4 (g)
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Tagged Calculate, celcius, chemistry, degrees celcius, delta, energy, equilibrium, formation, free energy, kj, mol, reaction, Temperature
how do you calculate the equilibrium constant if given the standard free energy of formation (delta Gf) at298K
how do you calculate the equilibrium constant if given the standard free energy of formation (delta Gf) at298K
Free Energy vs. Rate?
I know that spontaneity (negative free energy. negative delta G) do not necessarily mean that the rate is fast. But if the negative delta G value is large, thus, K is large, can you assume the process is fast? Why or why not?
Posted in Solar Power
Tagged delta, energy, free, negative free energy, process, rate, spontaneity, value