6.3 The Laws of Thermodynamics

6.3 The Laws of Thermodynamics

  • If the reaction is catalyzed, the activation energy is lower.
    • The diagram's horizontal axis shows the sequence of events.
  • Everything outside of the system is relevant to a particular case of energy transfer.
    • When heating a pot of water on the stove, the system includes the stove, the pot, and the water.
  • There are two types of systems.
    • Energy can be transferred between the system and its surroundings by an open system.
    • The system is open because it can lose heat.
    • A closed system can't transfer energy to its surroundings.
  • The organisms are open.
    • They consume energystoring molecule and release energy to the environment by doing work.
    • Energy is subject to the laws of physics.
    • The laws of the universe govern the transfer of energy.
  • The total amount of energy is constant.
    • There has always been the same amount of energy in the universe.
  • The first law of thermodynamics states that energy can be transferred from place to place, but it can't be created or destroyed.
    • The transfers and transformations of energy happen all the time.
    • Light bulbs produce light energy.
    • Natural gas is transformed into heat energy by gas stoves.
    • Plants convert sunlight energy into chemical energy that is stored within organic molecules.
  • The challenge for all living organisms is to obtain energy from their surroundings in forms that they can transfer or transform into usable energy to do work.
    • Living cells are able to meet this challenge.
    • The energy stored within sugars and fats is converted into energy by cellular chemical reactions.
  • It is easy to do work with the energy in the ATP molecule.
  • There are two examples of energy being transferred from one system to another.
    • Humans can convert the chemical energy in food into the movement of a bicycle.
    • Plants can convert light energy from the sun into chemical energy.
    • The primary tasks of a living cell may seem simple.
    • The second law of thermodynamics explains why these tasks are harder than they appear.
    • All of the energy transfers and transformations in the universe are not completely efficient.
    • Some amount of energy is lost in a form that is not usable.
    • This form is usually heat energy.
    • When an airplane flies through the air, it loses some of its heat energy because of the surrounding air.
    • The air molecule speed is temporarily increased by this friction.
    • During cellular reactions, some energy is lost as heat energy.
    • Warm-blooded creatures like us benefit from this because heat energy helps maintain our body temperature.
    • Some energy is lost in an unusable form, so no energy transfer is completely efficient.
  • Order and disorder are important concepts in physical systems.
    • The more energy a system loses to its surroundings, the more random it is.
    • There is high disorder and low energy.
    • The room would become messy if no work was put into it.
    • It would be in a state of high entropy.
    • In order to bring the room back to a state of order, energy must be put into the system in the form of the student doing work and putting everything away.
    • This state is not very good.
    • A car or house needs to be kept in an ordered state by constantly being maintained.
    • Left alone, a house's or car's entropy gradually increases through rust and degradation.
    • Chemical reactions have varying amounts of entropy as well.
    • As chemical reactions reach a state of equilibrium, the entropy increases, and as the molecule diffuses and spread out, the entropy also increases.
  • An experiment can be set up to understand how energy transfers work.
  • Take a block of ice.
    • The water has a high structural order because it is in solid form.
    • The molecule can't move very much because they are in a fixed position.
    • The ice's temperature is below freezing.
    • The system's entropy is low.
  • The ice should be allowed to melt at room temperature.
  • Living things are highly ordered, requiring constant energy input to maintain themselves in a state of low entropy.
    • Living systems lose some usable energy when they take in energy-storing molecules and transform them through chemical reactions.
    • Waste and by-products are not useful energy sources.
    • The system's surroundings are increased by this process.