Thermodynamics and Statistical Mechanics

Cooling rate refers to the speed at which a material loses heat during the cooling process. It can be measured by monitoring the temperature of the material over time using a thermometer or sensors. The cooling rate is influenced by factors such as the material's thermal conductivity, its surface area exposed to the surrounding environment, and the temperature difference between the material and its surroundings.

When a steadily flowing gas flows from a larger diameter pipe to a smaller diameter pipe the speed of gas is decreased and pressure become increased and the spacing between the streamlines less and the streamlines come very close to each other.

In adsorption, Gibbs free energy decreases because the adsorbate molecules are attracted to the surface of the adsorbent, reducing the overall energy of the system. This leads to a more stable configuration with a lower free energy. The decrease in Gibbs free energy indicates that the adsorption process is spontaneous at a given temperature and pressure.

Paraffin generally cools slower than water due to its lower thermal conductivity. This means that it takes longer for heat to transfer through paraffin, resulting in a slower rate of cooling compared to water.

This involves both the first and second laws of thermodynamics.

According to the first law, the energy you expend must come from somewhere. You have to take in that energy in the form of the chemical energy contained in the food before you can expend energy to move yourself around, grow, heal, breath, etc.

According to the second law, that energy will not flow into you spontaneously. You must expend energy to draw that energy into your body for use, in other words, you have to eat.

Microscopic viewpoint in thermodynamics focuses on individual molecules and their interactions, while macroscopic viewpoint looks at bulk properties of a system, such as temperature and pressure. These viewpoints help to describe and analyze the behavior of systems at different scales.

The temperature must heighten for ice to melt. The melting point of ice/water is about 0 degrees Celsius.

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Suppose we are at 1 atmosphere and we want to melt an ice cube (of pure water)

that is at -5oC. We give heat to the ice cube (hypothetically at very slow rate so we warm the ice cube in a homogeneous fashion). The temperature of the ice cube will rise to 00C before it starts to melt. During the melting process the heat given to the ice is invested in braking the intermolecular bonds. This is called the latent heat of fusion or

fusion enthalpy. Not until the ice completely melts, the temperature will start going up again.

250g of water at 10C needs to lose 1 cal/g/C or 2500 calories to drop temperature to zero.

The latent heat of fusion of water is 80 calories per gram at 0C so, the water needs to lose 20,000 calories to turn to ice at 0C

Finally, the ice needs to lose 0.316 cal/g/C or 790 calories to drop to -10C

The total heat released is then 2500 + 20,000 + 790 = 23,290 calories

The change in internal energy is the sum of heat added to the system and work done by the system on the surroundings. So, the change in internal energy is 2.500J (heat absorbed) - 7.655J (work done), resulting in a change of -5.155J.

Thermodynamics of diffusion involves the study of how energy changes affect the movement of particles from regions of high concentration to low concentration. It examines the relationship between temperature, pressure, and concentration gradients on the rate and direction of diffusion. This field helps in predicting and understanding diffusion processes in various systems.

One of the consequences of the 2nd law is that it is impossible for a power plant to achieve 100% efficiency. In fact the maximum efficiency is limited by the temperature of the boiler and temperature of the condenser for power plants powered by heat (like coal, gas fired, and nuclear).

1st. Principle-- If two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other.

2nd. Principle-- Heat energy and mechanical work are mutually convertible.

3rd.-- It is impossible to construct a mechanical device ( engine) whose sole purpose is to convert all of the heat energy supply to it into equal amount of work.

4th.-- The entropy of a pure crystalline substance at absolute zero temperature is zero

A steam trap is used to remove condensate (liquid) that forms in steam systems. If condensate is not removed, it can cause water hammer, reduce heat transfer efficiency, and affect the overall performance of the system. The steam trap helps prevent damage to equipment and ensures that only steam flows through the system.

Kinetic energy is the energy of motion, KE=mv2/2.

Thermal energy is different from kinetic energy.

Thermal energy is associated with the temperature of a body, the heat gained by increasing the temperature. That heat gives molecules more kinetic energy and more potential energy and may also give molecules more more electronic energy.

The work of Sadi Carnot, a French engineer, on the efficiency of heat engines in the early 19th century led to the formulation of the second law of thermodynamics. Carnot's insights on the limitations of heat engine efficiency laid the foundation for the development of the second law, which eventually became a fundamental principle in thermodynamics.

Direct heating can be thermodynamically wasteful because a significant amount of heat is lost to the surroundings during the heating process. This leads to lower efficiency in converting energy to heat, as the heat is not efficiently retained or transferred to the substance being heated. This wastage results in higher energy consumption and costs.

Specific heat is usually defined as the amount of energy that must be added to change the temperature. Another way to define it is the ratio between the amount of energy added and the change in temperature E/m·T(with units like joules/gram·°C) When water is at the saturation point and energy is added to it, instead of increasing in temperature, the water changes phase from liquid to gas. If you put the numbers back into the definition you get something like:

1 joule added to 1 gram of water yields a change of 0 °C so

Cp = 1/1∙0 = ∞.

Photosynthesis is an open system because energy enters the system and mass both enters and leaves the system. In very general terms photosynthesis is:

carbon dioxide + water + light ==> oxygen + plant growth

The exact process is a bit more complex, but the gist of it is that it is open because both mass and energy cross the boundaries of the system if the system is identified as the plant.

A major part of the heat transfer through a cavity wall lacking insulation is convection - and to a lesser degree radiation. When insulation is placed in the cavity between the walls it significantly reduces both convection (air doesn't move well through insulation like it does in empty space) and radition (the walls can't "see" each other through the insulation). For the insulation to be effective, the thermal conductivity of the material must be low enough that conduction through the insulation is much less than was present with convection.

The membrane serves as both an insulator and a diffusion barrier to the movement of ions. Ion transporter/pump proteins actively push ions across the membrane to establish concentration gradients across the membrane, and ion channels allow ions to move across the membrane down those concentration gradients,

The steam tables have 16 columns as follows:

pressure (absolute), temperature, specific volume of vapor, specific volume of liquid, heat of the liquid, heat of vaporization, total heat of the vapor, entropy of the liquid, entropy of vaporization, entropy of the vapor, internal heat of the liquid, internal heat of vaporization, and internal heat of the vapor (occasionally the external heat of the liquid, vaporization and vapor are included)

If the temperature and pressure of steam are known then cross referencing the heat or the volume of a known quantity of the steam can be done.

the heat content(enthalpy) of the liquid or vapor can be extrapolated from the chart, as can the entropy and internal energy. The enthalpy less the internal energy = the external energy (or the actual energy required to expand the liquid to a vapor)

By determining the starting heat content of steam and final or exhaust heat content of steam the efficiency of a steam engine can be determined. Along with these calculations are the determinations of heat losses, steam quality, loss to entropy,...etc. all calculated using various instruments and the steam tables.

To decrease the entropy of a static body, you would need to decrease the disorder or randomness of its particles. This can be achieved by cooling the body, which can lower the thermal motion of its particles and reduce their entropy. Other methods include applying pressure to order the particles or removing impurities that contribute to disorder.