سؤال قراءة ستيب محلول — المفردات في السياق (تدريب 7895)

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.