Thermodynamics

Thermodynamics By Bro. Balogun Arinwaka (Gary C. Booker)

What is Thermodynamics? ●

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Thermodynamics is the study of how heat energy and radiation behaves. Thermodynamics is a very important topic in Chemistry and Physics. It is also a very important process of understanding key concepts in biology. There are two very important concepts that form the foundation for understanding thermodynamics.

Some things about heat ●

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The natural temperature of your body is 98.6 degrees. When your body looses heat faster than it can internally replace it, it instinctively starts to shiver. Shivering produces mechanical energy that is converted into heat energy. Your skin develops “goosebumps” to increase it's ability as an insulator. Insulators are objects/substances that can trap heat. Heat has a tendency to rise.

Measuring Heat ●

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Heat and Temperature are not the same thing. Heat is the energy associated with the movement of molecules. Temperature is a measurement of the speed of molecules. The SI Unit for heat is the Calorie. The SI Units for Temperature are degrees Farenheit, Degrees Celsius and Degrees Kelvin. The SI Unit for energy is the Joule.

The Earth's Troposphere ●

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A cold front is a boundary where a cold air mass is replacing a warm air mass. Cold fronts move very fast because the cold air causes the hot air preceeding the cold air mass to quickly rise above it.. This rush of rising air forms cumulus clouds. The cumulus clouds eventually become cumulonimbus clouds, which produce thunderstorms.

The Earth's Troposphere ●

The tendency of heat to rise is also why warm fronts move slower than cold fronts. The warm air continues to ride at the boundary zone. The air mass does not move forward until the volume of warm air eventually pushes the cold air out of the way.

The States of Matter ●

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There are three states of matter for every substance. They are solids, liquids and gases. All states of matter depend on heat. A solid is a substance that has a definite shape and a definite volume. Examples include, soil, cotton, and wood. The atoms and molecules of solids are packed very close together A liquid is a substance that does not have a definite shape, but has a definite volume. An example is water, juice, and vinegar. The atoms and molecules of solids are packed together in amounts moderate enough to cause “looseness,” which allows a liquid to flow. A liquid's ability to resist free flow is called VISCOSITY. A gas is a substance that does not have a definite shape or volume. An example is carbon dioxide, helium and Nitrous Oxide (poisonous). Gas molecules and atoms, compared to solids and liquids, are not close together.

The States of Matter ●

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Changes in states of matter are physical changes. They do not alter the chemical identity of the substance. For example, water can exist as water vapor (gas), water in liquid form, or ice (solid). Changing a substance from solid to liquid is called melting. The temperature at which a substance melts is called its melting point. Changing a substance from a liquid to a gas is called boiling, or evaporation. The temperature at which a substance boils is called its boiling point. Changing a substance from a gas to a liquid is called condensation. The temperature at which a substance condenses is its condensation point. Changing a substance from a liquid to a solid is called freezing. The temperature at which a substance freezes is called it's freezing point. Changing a substance from a solid to a gas without passing through the liquid state is called sublimination. This only occurs with certain substances at certain temperatures. In atmospheric pressure, carbon dioxide does this. This is why frozen carbon dioxide is called “dry ice.”

The relationship between heat and pressure. ●

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Pressure is the amount of force applied perpendicularly to a surface. equal to force divided by area. There is a relationship between pressure and heat. This makes pressure very important in analyzing any process involving heat. Processes that involve heat are called isothermic processes. A process that does not involve heat is an adiabatic process. Objects under pressure take longer to boil. This is why water comes to a boil faster in a house that is located in the mountains.

Thermodynamic systems ●

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In Thermodynamics, a system is the set of all objects involved in the transfer of energy. The boundary of a system separates the objects exchanging the energy from outside objects that are, for all practical purposes, unimportant.

The First Law of Thermodynamics: The First Law of Thermodynamics states the following: ●

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Energy is omnipresent. It is neither created or destroyed. It transfers from one form to another. The change of internal energy is equivalent to the difference between the energy put into a system and the work done by the system. Mathematically, this is expressed as the following:

Image courtesy of (http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/firlaw.html)

What does that mean? Suppose a boiling egg rises to the meniscus of the boiling water. Suppose the egg rose 0.03 m (3 cm) from the water with a force of 2 newtons. Using the formula for work from physics (work = force x distance), we can calculate the work to be 0.06 Joules. Suppose we knew that the change of energy was 8 Joules. That would mean that the amount of heat energy released would have to be 8.06 Joules.

What does that mean? If you put energy into this system, it will come out in some form or fashion. If you put a lid on this pot, then the top will eventually start to rock and steam will escape from underneath it. When this happens, the heat energy in this system performing work on the pot lid.

The Second Law of Thermodynamics The second law of thermodynamics states the following: ●

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Heat energy can never be fully converted into mechanical energy. Perpetual motion is not possible.

This means that you cannot convert all of the heat energy in this pot into moving the egg. Some heat will remain in the boiling water.

Radiation ●

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Radiation is the emission of energy in waves and particles. Heat transfer can occur through this process. An obvious example of this is sunlight. Dark colored objects absorb heat more than lightly colored objects. This phenomenon is known as Blackbody Radiation. A blackbody is defined as an object that ideally absorbs all radiation emitted into it.

Radiation ●

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UV radiation plays a vital role in isothermic chemical processes on Earth, as well as on other planets. None of the biogeochemical cycles can operate without the heat energy obtained from the sun's UV Radiation. Life forms also depend on UV radiation. The human body emits its own level of radiation. The chlorophyll in plants, and melanin in animals utilize sunlight for internal functions.

Radiation ●

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The greenhouse effect is the atmosphere's ability to hold heat. When UV waves and photons enter the atmosphere, heat transfer occurs. Some heat escapes into space, while the rest of it remains trapped in the atmosphere. The effect is named after greenhouses, which are use UV sunlight to hold in heat for plants during cold weather.