APES notes - Energy and Matter Nuclear processes matter...

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Energy and Matter Nuclear processes- matter converted to energy Energy is the work needed to move matter and the heat that flows from hot to cooler samples of matter. Matter is anything that has mass and takes up space. Mass is how much matter something has (matter consists of atoms, the smallest particle of an element that still retains the identity of that element) Elements are the purest forms of matter (92 naturally known) Atoms get their mass (weight) from their nuclei, protons, and neutrons; volume from surrounding electron clouds (mostly empty space; electrons “great distance” from the nucleus) Electrons have negligible mass Matter is conserved in any physical process ( law of conservation of matter or mass ). Chemical reactions rearrange atoms to form new substances, whereas physical processes (like phase changes) do not alter the identity of the substance. Chemical: 2H 2 + O 2 = 2H 2 O Physical: H 2 O(s) → H 2 O(l) Energy is also conserved in any chemical/physical process: 1 st law of thermodynamics (law of conservation of energy) Matter can be recycled indefinitely but energy degrades with use (to heat, disperses) 2 nd law of thermodynamics : in any/ever spontaneous process, the entropy of the universe increases (entropy is a measure of disorder)- the universe is increasing in disorder, resort of the “big bang” Spontaneity can be predicted in the following equation: ΔH – TΔS = ΔG ΔH = (change in H: heat) enthalpy T = temperature (k) S = entropy G = Gibb’s free energy ( 3 rd law of thermodynamics : any crystalline structure at absolute zero (0 k) has now movement) +ΔS = increase in entropy (thermodynamically favored) -ΔH = heat produced/released: exothermic (td favored) -ΔG = spontaneous +ΔG = nonspontaneous ΔH ΔS ΔG Spontaneous - + - Always + - + Never - - Depends on ΔT At low T + + Depends on ΔT At high T Various forms of energy on earth, most of which can ultimately be traced back to the sun. A small percentage comes from the spontaneous decay of radioactive elements on the crust. Radiant energy (comes directly from sun), stored chemical energy (bonds in coal, oil, natural gas, etc.), mechanical energy (used to move/lift matter), electrical energy (movement of electrons, as in batteries), nuclear energy (stored in nuclei of atoms) Potential energy is stored; kinetic energy is energy of motion Power is the rate of energy delivery; measured in horse power or watts
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Industrial revolution - widespread replacement of manual labor by machines that began in Britain and spread in the 18 th c. Goods traditionally made in the house or small workshops began to be manufactured in the factory Led to growth of cities as people moved from rural areas into urban communities in search of work Brought economic improvement for most people in industrialized societies Costs: Lower classes of society suffered economically Factory pollutants Greater land use Drastic population growth (+ green revolution) Extensive loss of habitat for plants/animals
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APES notes - Energy and Matter Nuclear processes matter...

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