{
  "name": "Chemistry 201",
  "front_language": "Chemistry",
  "back_language": "English",
  "cards": [
    { "front": "Ideal gas law", "back": "The equation PV = nRT, which relates the pressure, volume, temperature, and number of moles of an ideal gas.", "level": "201", "tags": ["gas-laws"], "example_front": "Using the ideal gas law, chemists can calculate the volume of a gas at a given temperature and pressure.", "example_back": "R is the universal gas constant, the same for all ideal gases." },
    { "front": "Boyle's Law", "back": "At constant temperature, the pressure of a gas is inversely proportional to its volume.", "level": "201", "tags": ["gas-laws"], "example_front": "When a piston compresses a gas, its pressure increases according to Boyle's Law.", "example_back": "Doubling the pressure on a gas at constant temperature halves its volume." },
    { "front": "Partial pressure", "back": "The pressure that one gas in a mixture would exert if it occupied the container alone.", "level": "201", "tags": ["gas-laws"], "example_front": "The partial pressure of oxygen in air is about 0.21 atm at sea level.", "example_back": "Dalton's Law states that total pressure equals the sum of the partial pressures of each gas." },
    { "front": "STP (Standard Temperature and Pressure)", "back": "A reference condition defined as 0°C (273.15 K) and 1 atm, used to compare gas measurements.", "level": "201", "tags": ["gas-laws"], "example_front": "At STP, one mole of an ideal gas occupies about 22.4 liters.", "example_back": "STP gives chemists a common baseline so gas volumes from different experiments can be compared." },

    { "front": "Enthalpy", "back": "A measure of the total heat content of a system at constant pressure, denoted H.", "level": "201", "tags": ["thermodynamics"], "example_front": "The enthalpy change of a reaction tells you whether it releases or absorbs heat.", "example_back": "ΔH is negative for exothermic reactions and positive for endothermic reactions." },
    { "front": "Exothermic reaction", "back": "A chemical reaction that releases heat into its surroundings, causing the temperature to rise.", "level": "201", "tags": ["thermodynamics"], "example_front": "Combustion is an exothermic reaction — burning fuel releases heat and light.", "example_back": "In an exothermic reaction, the products have less energy than the reactants." },
    { "front": "Endothermic reaction", "back": "A chemical reaction that absorbs heat from its surroundings, causing the temperature to drop.", "level": "201", "tags": ["thermodynamics"], "example_front": "Dissolving ammonium nitrate in water is endothermic — the solution feels cold.", "example_back": "In an endothermic reaction, the products have more energy than the reactants." },
    { "front": "Entropy", "back": "A measure of the disorder or randomness of a system, denoted S.", "level": "201", "tags": ["thermodynamics"], "example_front": "Ice melting into water is an increase in entropy because the molecules become less ordered.", "example_back": "The second law of thermodynamics states that the entropy of an isolated system tends to increase over time." },

    { "front": "Reaction rate", "back": "A measure of how quickly reactants are converted into products, usually expressed as a change in concentration over time.", "level": "201", "tags": ["kinetics"], "example_front": "Increasing the temperature usually increases the reaction rate.", "example_back": "Reaction rates are often measured by tracking how fast a reactant's concentration decreases." },
    { "front": "Activation energy", "back": "The minimum amount of energy required for reactant particles to collide and form products.", "level": "201", "tags": ["kinetics"], "example_front": "A catalyst works by lowering the activation energy needed for a reaction to occur.", "example_back": "Reactions with high activation energy tend to proceed slowly at room temperature." },
    { "front": "Rate law", "back": "An equation that expresses the rate of a reaction as a function of the concentrations of its reactants.", "level": "201", "tags": ["kinetics"], "example_front": "For the reaction A + B → C, the rate law might be written as rate = k[A][B].", "example_back": "The exponents in a rate law are determined experimentally, not from the balanced equation." },
    { "front": "Half-life", "back": "The time required for half of a given quantity of a substance to react or decay.", "level": "201", "tags": ["kinetics"], "example_front": "Carbon-14 has a half-life of about 5,730 years, which is why it's used to date ancient artifacts.", "example_back": "After two half-lives, only one-quarter of the original substance remains." },

    { "front": "Chemical equilibrium", "back": "The state of a reversible reaction in which the rates of the forward and reverse reactions are equal.", "level": "201", "tags": ["equilibrium"], "example_front": "At equilibrium, the concentrations of reactants and products remain constant over time.", "example_back": "Equilibrium doesn't mean the reaction has stopped — both reactions are still occurring, just at equal rates." },
    { "front": "Equilibrium constant (K)", "back": "A number that expresses the ratio of product concentrations to reactant concentrations at equilibrium, each raised to their stoichiometric powers.", "level": "201", "tags": ["equilibrium"], "example_front": "A large value of K means the reaction favors the formation of products at equilibrium.", "example_back": "K depends on temperature but not on the initial concentrations of reactants." },
    { "front": "Le Chatelier's Principle", "back": "If a system at equilibrium is disturbed, it will shift to partially counteract the disturbance.", "level": "201", "tags": ["equilibrium"], "example_front": "Adding more reactant to a system at equilibrium shifts the reaction to produce more product, according to Le Chatelier's Principle.", "example_back": "This principle applies to changes in concentration, pressure, volume, and temperature." },
    { "front": "Solubility product (Ksp)", "back": "The equilibrium constant for the dissolution of a sparingly soluble ionic compound in water.", "level": "201", "tags": ["equilibrium"], "example_front": "A small Ksp value means the compound is only slightly soluble in water.", "example_back": "Ksp can be used to predict whether a precipitate will form when two solutions are mixed." },

    { "front": "Buffer", "back": "A solution that resists changes in pH when small amounts of acid or base are added, usually made from a weak acid and its conjugate base.", "level": "201", "tags": ["acids-bases"], "example_front": "Blood contains a buffer system that keeps its pH close to 7.4 even when acids are produced by metabolism.", "example_back": "Buffers work best within about one pH unit of the pKa of the weak acid they contain." },
    { "front": "Titration", "back": "A laboratory technique used to determine the concentration of a solution by reacting it with a solution of known concentration.", "level": "201", "tags": ["acids-bases"], "example_front": "During a titration, a base is slowly added to an acid until the indicator changes color at the endpoint.", "example_back": "The point where moles of acid equal moles of base is called the equivalence point." },
    { "front": "Conjugate acid-base pair", "back": "Two species that differ from each other by the presence or absence of a single proton (H⁺).", "level": "201", "tags": ["acids-bases"], "example_front": "In the reaction HCl + H₂O → H₃O⁺ + Cl⁻, H₂O and H₃O⁺ form a conjugate acid-base pair.", "example_back": "A strong acid has a weak conjugate base, and vice versa." },
    { "front": "pKa", "back": "The negative base-10 logarithm of the acid dissociation constant (Ka), used to compare the strength of acids.", "level": "201", "tags": ["acids-bases"], "example_front": "A lower pKa value indicates a stronger acid.", "example_back": "Acetic acid has a pKa of about 4.76, while a strong acid like HCl has a pKa well below 0." },

    { "front": "Redox reaction", "back": "A reaction in which electrons are transferred between substances, involving both oxidation and reduction.", "level": "201", "tags": ["electrochemistry"], "example_front": "The rusting of iron is a redox reaction in which iron is oxidized and oxygen is reduced.", "example_back": "Redox stands for 'reduction-oxidation' — the two processes always occur together." },
    { "front": "Oxidation", "back": "The loss of electrons by an atom, ion, or molecule, often resulting in an increase in oxidation number.", "level": "201", "tags": ["electrochemistry"], "example_front": "When zinc reacts with copper sulfate, the zinc atoms undergo oxidation, losing electrons to become Zn²⁺.", "example_back": "A helpful memory trick is 'OIL RIG' — Oxidation Is Loss, Reduction Is Gain (of electrons)." },
    { "front": "Reduction", "back": "The gain of electrons by an atom, ion, or molecule, often resulting in a decrease in oxidation number.", "level": "201", "tags": ["electrochemistry"], "example_front": "In the same reaction, copper ions undergo reduction, gaining electrons to form solid copper.", "example_back": "The substance that is reduced is called the oxidizing agent, because it causes oxidation in another substance." },
    { "front": "Electrochemical cell", "back": "A device that produces electrical energy from a spontaneous redox reaction, or uses electrical energy to drive a non-spontaneous one.", "level": "201", "tags": ["electrochemistry"], "example_front": "A battery is an electrochemical cell that converts chemical energy into electrical energy.", "example_back": "Electrochemical cells that generate electricity are called galvanic or voltaic cells." },

    { "front": "Hydrocarbon", "back": "An organic compound composed entirely of hydrogen and carbon atoms.", "level": "201", "tags": ["organic-chemistry"], "example_front": "Methane (CH₄) is the simplest hydrocarbon and the main component of natural gas.", "example_back": "Hydrocarbons are classified as alkanes, alkenes, alkynes, or aromatics depending on their bonding." },
    { "front": "Functional group", "back": "A specific group of atoms within a molecule that gives the molecule its characteristic chemical properties and reactivity.", "level": "201", "tags": ["organic-chemistry"], "example_front": "The hydroxyl group (-OH) is the functional group that defines alcohols.", "example_back": "Molecules with the same functional group tend to undergo similar chemical reactions." },
    { "front": "Isomer", "back": "One of two or more compounds that have the same molecular formula but different arrangements of atoms.", "level": "201", "tags": ["organic-chemistry"], "example_front": "Butane and isobutane are isomers — both have the formula C₄H₁₀ but different structures.", "example_back": "Isomers can have very different physical and chemical properties despite sharing a formula." },
    { "front": "Polymer", "back": "A large molecule made up of many repeating smaller units, called monomers, bonded together.", "level": "201", "tags": ["organic-chemistry"], "example_front": "Polyethylene is a polymer made by linking together thousands of ethylene monomers.", "example_back": "Many plastics, as well as natural materials like DNA and proteins, are polymers." },

    { "front": "Radioactive decay", "back": "The spontaneous process by which an unstable atomic nucleus loses energy by emitting radiation.", "level": "201", "tags": ["nuclear-chemistry"], "example_front": "Uranium-238 undergoes radioactive decay, eventually transforming into lead through a series of steps.", "example_back": "The rate of radioactive decay is measured using a substance's half-life." },
    { "front": "Alpha particle", "back": "A particle consisting of two protons and two neutrons (equivalent to a helium-4 nucleus) emitted during certain types of radioactive decay.", "level": "201", "tags": ["nuclear-chemistry"], "example_front": "Alpha particles are relatively heavy and can be stopped by a sheet of paper or skin.", "example_back": "When an atom emits an alpha particle, its atomic number decreases by 2 and its mass number decreases by 4." },
    { "front": "Fission", "back": "The splitting of a large, unstable atomic nucleus into two smaller nuclei, releasing a large amount of energy.", "level": "201", "tags": ["nuclear-chemistry"], "example_front": "Nuclear power plants generate electricity using the energy released by the fission of uranium atoms.", "example_back": "Fission reactions can release neutrons that trigger further fission, creating a chain reaction." },
    { "front": "Fusion", "back": "The process of combining two light atomic nuclei into a single heavier nucleus, releasing energy.", "level": "201", "tags": ["nuclear-chemistry"], "example_front": "The Sun produces its energy through the fusion of hydrogen nuclei into helium.", "example_back": "Fusion requires extremely high temperatures and pressures to overcome the repulsion between nuclei." }
  ]
}