Search results for “Catalyst”

Catalyst Chemical Kinetics & Catalysis Dimensionless A substance that increases the rate of a reaction by providing an alternative pathway of lower activation energy, without being consumed.

Catalyst Poisoning Chemical Kinetics & Catalysis Dimensionless The loss of catalytic activity caused by a substance binding irreversibly to the active sites.

Effect of a Catalyst on Equilibrium Chemical Equilibrium Dimensionless A catalyst changes how quickly equilibrium is reached but never where that equilibrium lies. K unchanged

Active Site Chemical Kinetics & Catalysis Dimensionless The specific region of a catalyst or enzyme at which the reacting molecules bind and are transformed.

Catalysis Chemical Kinetics & Catalysis Dimensionless The process by which a reaction rate is increased through the action of a catalyst.

Enzyme Biochemistry & Polymer Chemistry Dimensionless A biological catalyst, almost always a protein, that accelerates a specific biochemical reaction.

Friedel–Crafts Reaction Organic Chemistry Dimensionless The introduction of an alkyl or acyl group onto an aromatic ring using a Lewis acid catalyst. ArH + RCl + AlCl₃ → ArR + HCl

Heterogeneous Catalysis Chemical Kinetics & Catalysis Dimensionless Catalysis in which the catalyst is in a different phase from the reactants, usually a solid with gaseous or liquid reagents.

Homogeneous Catalysis Chemical Kinetics & Catalysis Dimensionless Catalysis in which the catalyst is in the same phase as the reactants.

Optimum Conditions for Industrial Yield Chemical Equilibrium Various The compromise set of temperature, pressure and catalyst chosen to balance equilibrium yield against reaction rate and cost.

Promoter Chemical Kinetics & Catalysis Dimensionless A substance that has little catalytic activity itself but greatly increases the effectiveness of a catalyst.

Selectivity Chemical Kinetics & Catalysis Dimensionless The ability of a catalyst to direct a reaction towards one particular product among several possible ones. selectivity = desired product / total product

Activation Energy Chemical Kinetics & Catalysis kJ/mol The minimum energy that colliding particles must possess for a reaction to occur. Ea = E(transition state) − E(reactants)

Addition Polymerisation Biochemistry & Polymer Chemistry Dimensionless Polymerisation in which unsaturated monomers add to one another with no loss of any atoms. n CH₂=CH₂ → –(CH₂–CH₂)ₙ–

Chemical Equation Stoichiometry & Chemical Reactions Dimensionless A symbolic representation of a chemical reaction showing reactants on the left and products on the right. aA + bB → cC + dD

Chemical Kinetics Chemical Kinetics & Catalysis mol/(L·s) The study of reaction rates, the factors that influence them, and the step-by-step mechanisms by which reactions occur.

Effective Collision Chemical Kinetics & Catalysis Dimensionless A collision that actually leads to reaction because it has both sufficient energy and correct orientation.

Enzyme Specificity Biochemistry & Polymer Chemistry Dimensionless The ability of an enzyme to select one substrate, or one class of substrate, and catalyse one particular reaction.

Equilibrium Constant Chemical Equilibrium Various The fixed ratio of product to reactant terms, each raised to its stoichiometric power, that characterises a reaction at a given temperature. K = Π[products]^ν / Π[reactants]^ν

Equilibrium Yield Chemical Equilibrium Dimensionless The proportion of reactant converted to product once equilibrium has been reached. yield = n_product / n_theoretical

Esterification Stoichiometry & Chemical Reactions Dimensionless The acid-catalysed condensation of a carboxylic acid with an alcohol to form an ester and water. RCOOH + R′OH ⇌ RCOOR′ + H₂O

Fuel Cell Electrochemistry & Redox V An electrochemical cell that generates electricity continuously from a fuel and oxidant supplied from outside.

Hydrogen–Oxygen Fuel Cell Electrochemistry & Redox V A fuel cell in which hydrogen is oxidised at the anode and oxygen reduced at the cathode, producing only water. 2H₂ + O₂ → 2H₂O, E° = 1.23 V

Nuclear Chemistry Nuclear & Radiochemistry Dimensionless The study of changes that occur in atomic nuclei and of the properties of radioactive substances.

Results for “Catalyst”