سؤال قراءة ستيب محلول — المفردات في السياق (تدريب 5707)

Catalysts are very important in controlling the rate of reactions. A catalyst is a chemical that increases the speed or rate of a chemical reaction without undergoing permanent chemical change. Many industrial and biological processes need catalysts for efficiency; the reactions are too slow without them. Catalysts are fascinating chemicals. The reaction between hydrogen and nitrogen gas to form ammonia does not occur at a significant rate, even at high pressures and high temperatures. If some finely divided iron is added to the vessel, however, the rate of the reaction increases dramatically and the reaction becomes productive. Iron is not a reactant and does not chemically change in the reaction. The iron functions as a catalyst.