Untitled Flashcards Set

Electrochemistry:

• Oxidation/Reduction:
  Oxidation is the loss of electrons, while reduction is the gain of electrons. The species that undergoes oxidation is called the reducing agent (or reductant), and the species that undergoes reduction is called the oxidizing agent (or oxidant).

• Voltaic Cells:
  A voltaic cell (also called a galvanic cell) is an electrochemical cell that generates electrical energy through a spontaneous chemical reaction. In a voltaic cell, electrons flow from the anode (where oxidation occurs) to the cathode (where reduction occurs).

• Standard Cell Potentials:
  The standard cell potential (denoted as Ecell) is the potential difference between the two electrodes of a voltaic cell under standard conditions. A positive Ecell value indicates a spontaneous reaction.

Nuclear Chemistry:

• Nuclear Symbols:
  A nuclear symbol represents the composition of an atomic nucleus. It consists of the element's symbol, the atomic number (number of protons), as a subscript, and the mass number (sum of protons and neutrons) as a superscript.

• Radioactive Decay:
  Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. This occurs to make the nucleus more stable.

• Alpha Decay:
  During alpha decay, an unstable nucleus emits an alpha particle, which consists of two protons and two neutrons. The mass number of the parent nucleus decreases by 4, and the atomic number decreases by 2.

• Positron Emission:
  Positron emission involves the emission of a positron, which has the same mass as an electron but a positive charge. A proton in the nucleus is converted into a neutron, and the atomic number decreases by 1, but the mass number remains unchanged.

• Fission/Fusion:

  • Nuclear fission is a nuclear reaction in which a large atomic nucleus splits into two or more smaller nuclei, releasing energy and neutrons that can cause further fission.

  • Nuclear fusion occurs when two or more atomic nuclei combine to form a larger nucleus, releasing a large amount of energy (this is the process that powers the sun).

• Half-life:
  Half-life is the time it takes for half of the radioactive nuclei in a sample to decay.

Thermodynamics:

• Internal Energy:
  Internal energy (denoted as U) is the sum of the kinetic and potential energies of all the particles in a system. It is a state function, meaning it depends only on the current state of the system (e.g., temperature, pressure) and not on how the system arrived at that state.

• Heat and Work:
  Heat is the energy transferred to or from a system due to a temperature difference between the system and its surroundings. Work is the energy transferred when a force moves an object through a distance.

• Enthalpy:
  Enthalpy (denoted as H) is a thermodynamic property that represents the heat content of a system at constant pressure. It can be used to calculate the heat absorbed or released during a chemical reaction.

• Spontaneous Process:
  A spontaneous process is a physical or chemical change that occurs naturally without external influence.

• Entropy:
  Entropy (denoted as S) is a measure of the disorder or randomness in a system. Higher entropy indicates greater disorder.

• Free Energy:
  Free energy (denoted as G) is a thermodynamic quantity used to predict the spontaneity of a process. It is given by the equation G = H - TS, where H is enthalpy, T is temperature, and S is entropy.

• Standard Free Energy of Formation:
  The standard free energy of formation is the free energy change when one mole of a substance is formed from its elements in their standard states under standard conditions (usually 25 degrees Celsius and 1 atm).

Equilibrium:

• Equilibrium Constant (K):
  The equilibrium constant (K) is a value that describes the ratio of the concentrations of the products to the concentrations of the reactants at equilibrium.

• Chemical Equilibrium:
  Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant over time.

• Le Chatelier’s Principle:
  Le Chatelier's principle states that if a system at equilibrium is subjected to a stress (such as changes in concentration, temperature, or pressure), the system will shift in the direction that relieves the stress.

• Conjugate Acid/Conjugate Base:
  A conjugate acid is the species formed when a base gains a proton, and a conjugate base is the species formed when an acid loses a proton.

• Equilibrium Reactions:
  In an equilibrium reaction, the reaction can proceed in either the forward or reverse direction, but the concentrations of reactants and products remain constant when equilibrium is reached.