Question

ΔU is equal to:
A) Isobaric work
B) Adiabatic work
C) Isothermal work
D) Isochoric work

Answer 1

Hydrogen electrode is a redox electrode which forms the basis of the thermodynamic scale of oxidation and reduction potentials. pH means potential of hydrogen. pH scale is used to specify the acidity and basicity of an aqueous solution.

Complete step-by-step solution:
There are four fundamental laws of thermodynamics. First is the zeroth law of thermodynamics states that if body A is in equilibrium with B, and body B is in equilibrium with C, then body A and C are in equilibrium with each other.

First law of equilibrium can be stated in various ways like total mass and energy of the system remains constant or energy can be transferred from one system to another but can neither be created nor be destroyed. Or we can say it is impossible to construct perpetual motion machines which could produce work without consuming any energy.

Mathematically we can say that- $dU = dq + dW$ or $\Delta U = q + w$
So we can see here the change in energy depends on heat and work. For an isobaric system, pressure should be constant or change in pressure is zero. Now we have $W = - Pdv$ so $\Delta U = q - pdv$, so change in energy is not equal to isobaric work.

For an isothermal system, change in temperature should be equal to zero. And at constant temperature change in energy will be equal to zero.

For adiabatic work, heat value is zero so change in energy is equal to the work. $\Delta U = 0 - W$
$\Delta U = - {W_{adiabatic}}$

Therefore the correct answer is option ‘B’, adiabatic process.

Note: Second law of thermodynamics can be expressed as heat does not spontaneously pass from a colder body to a warmer body. Or the entropy function of a system of bodies tends to increase in all physical and chemical processes. Third law of thermodynamics states that a system's entropy approaches a constant value as the temperature approaches absolute zero. Except for glasses, the entropy of the system at absolute zero is almost equal to zero.