catalyst

تعريف catalyst في الإنجليزية الإنجليزية القاموس.: A substance that increases the rate of a chemical reaction without being consumed in the process
Enzymes, the catalysts of biological systems, are remarkable molecular devices that determine the pattern of chemical transformations.; Someone or something that encourages progress or change
Rosa Parks was a true catalyst for change and she was only one person. Hearing about Rosa Parks and her protest showed me that there is hope for me and all the students in Ms. G's classes to truly be catalysts for change.; A catalytic converter; A substance that speeds up a chemical reaction, but is not itself changed during the reaction; any substance that increases the rate of a chemical reaction and is not consumed as the reaction proceeds; Substance that speeds up a chemical process without actually changing the products of reaction; A substance that promotes a chemical reaction by lowering the activation energy without itself being changed in the end Enzyme is a type of catalyst; A chemical substance that increases the rate of reaction without being consumed; A substance that increases the rate of a chemical reaction, without being consumed or produced by the reaction Enzymes are catalysts for many biochemical reactions; You can describe a person or thing that causes a change or event to happen as a catalyst. I very much hope that this case will prove to be a catalyst for change He said he saw the bank's role as a catalyst to encourage foreign direct investment; A substance that increases the rate of a chemical reaction without being consumed in the reaction A substance that lowers the activation energy for a chemical reaction by providing an alternate pathway for the reaction; a substance that modifies, especially increases, the rate of chemical reaction without being consumed or changed in the process; A substance that either speeds up or slows down a chemical reaction but which does not experience a permanent chemical change in the process; a substance that alters the velocity of a chemical reaction and may be recovered essentially unaltered in form and amount at the end of the reaction; Substance whose presence increases the rate of a chemical reaction, e g , acid catalyst added to an epoxy resin system to accelerate drying time; (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected; A catalyst is substance which increases the rate of a chemical reaction without itself being used up in the reaction; A substance that causes or accelerates a chemical reaction when added to the reactants in a minor amount, and that is not consumed in the reaction; In chemistry, a catalyst is a substance that causes a chemical reaction to take place more quickly. Any substance of which a small proportion notably affects the reaction rate of a chemical reaction without itself being changed or consumed (see catalysis). One molecule may transform several million reactant molecules a minute. Catalysts may be gaseous, liquid, or solid; they may be inorganic compounds, organic compounds, or complex combinations. They tend to be highly specific, reacting with only one substance or a small set of substances. Substances that reduce the effectiveness of catalysts by altering them or blocking reactants' access to them are called catalyst inhibitors or catalyst poisons. Catalysts are essential to virtually all industrial chemical reactions, especially in petroleum refining and synthetic organic chemical manufacturing. Most solid catalysts are transition elements (metals) or their oxides in finely divided or porous form. In a car's catalytic converter, the platinum catalyst converts unburned hydrocarbons and nitrogen compounds to products less harmful to the environment. Water, especially saltwater, catalyzes oxidation (see oxidation-reduction) and corrosion. Enzymes are among the most active and selective catalysts known; A chemical (metal) substance by which its mere presence accelerates, assists, retards or permits a chemical reaction but remains chemically unchanged in nature or amount at the end of the reaction; A substance that increases the rate of a chemical reaction without being consumed in the reaction by lowering the activation energy (Ea) for the reaction; is a substance that can increase or decrease the rate of a chemical reaction between the other chemical species without being consumed in the process; a substance which increases the rate of a chemical reaction without being consumed or produced by the reaction Catalysts speed both the forward and reverse reactions, without changing the position of equilibrium Enzymes are catalysts for many biochemical reactions; Someone or something that helps or encourages progress or change; - a substance which alters the rate of a chemical reaction without being used up itself in the reaction; something that causes an important event to happen; "the invasion acted as a catalyst to unite the country"; A substance that alters the speed of a chemical reaction and does not appear in the final product and undergoes no permanent changes search; A substance that activates a chemical reaction and is not itself changed in the process; A substance which increases the rate of a chemical reaction without being consumed in the process; Substance that aids or promotes a chemical reaction between other substances, but does not, itself, enter into the reaction; {i} substance that accelerates a chemical reaction but remains unchanged by it; someone or something which provokes change; A material which speeds up or stimulates a chemical reaction without being significantly chemically altered by the reaction; an agent that promotes or accelerates a chemical reaction without itself being consumed; a substance that increases the rate of a chemical reaction without being consumed itself; A substance that promotes a chemical reaction by lowering the activation energy of a chemical reaction, but which itself remains unaltered at the end of the reaction (See Catalytic antibody, Catalytic RNA )
Vandenberg catalyst: an aluminoxane, prepared from an alkyl-aluminium and water, used as a catalyst in the manufacture of polyether elastomers
stereospecific catalyst: a catalyst that preferentially catalyses the formation of one of a pair of stereoisomers, or one of a set of stereoisomeric polymers
triphase catalyst: A solid phase-transfer catalyst, often in the form of beads, that catalyzes a reaction between a liquid and a gas
catalysts: plural of catalyst
served as a catalyst: made something faster, urged, spurred