Chemistry in Society Flashcards
activated complex
is a very unstable arrangement of atoms formed at the maximum of the potential energy barrier, during a chemical reaction
activation energy
the minimum kinetic energy required by colliding particles before reaction will occur, since a high energy activated complex must be formed
actual yield
the quantity of desired product formed in a reaction under the prevailing reaction conditions
atom economy
measures the proportion of the total mass of all starting materials converted into the desired product in the balanced equation
catalyst
increases the rate of a chemical reaction by providing an alternative pathway with a lower activation energy
collision theory
states that, for a chemical reaction to occur, particles must collide with the correct geometry and sufficient energy to react
endothermic reactions
absorb heat energy from the surroundings
enthalpy change
the change in heat energy when 1 mole of reactant is converted to product(s) at constant pressure
exothermic reactions
release heat energy, which is given up to the surroundings
limiting reagent
determines the extent of the reaction as, being fully used up, it causes the reaction to end
percentage yield
measures the degree to which the limiting reagent is converted into the desired product
potential energy diagram
shows the enthalpy of reactants and products, and the enthalpy change during a chemical reaction
temperature
a measure of the average kinetic energy of the particles in a substance
theoretical yield
the maximum possible amount of product in a reaction i.e. if all of the reactant(s) have been converted into product.
chromatography
an analytical method where mixtures are separated into their components by partitioning between a stationary and mobile phase
dynamic equilibrium
achieved when the rates of two opposing processes become equal, so that no net change results
end-point
the point at which the reaction is just complete
enthalpy of combustion
is the enthalpy change that occurs when 1 mole of a substance is burned completely in oxygen
equilibrium
the state reached by a reaction mixture when the rates of forward and reverse reactions have become equal
hess’s law
the enthalpy change for a chemical reaction is independent of the route taken, providing the starting point and finishing point is the same for both routes
mean molar enthalpy
the average energy required to break one mole of bonds, for a bond that occurs in a number of compounds
molar bond enthalpy
the energy required to break one mole of bonds in a diatomic molecule
molar volume
the volume occupied by one mole of a substance
retention time
the time taken for an individual peak to traverse the gas-liquid chromatographic column after the injection time
