A. lowering the temperature. B. decreasing the concentration of reactants. C. adding a catalyst. D. reducing the pressure. 相关知识点: 试题来源: 解析 C。解析:添加催化剂可以提高化学反应的速率。选项 A 降低温度通常会使反应速率减慢。选项 B 降低反应物浓度也会使反应速率减慢。选项 D 降低压力对...
1.6Which ONE of the following statements about a chemical reaction is CORRECT?The actual yield of a chemical reaction is usually ...C A equal to the percentage yield. B greater than the percentage yield. C less than the theoretical yield. D greater than the theoretical yield. 相关知识点:...
A catalyst is a substance that increases the rate of a chemical reaction without being chemically changed at the end of reaction. 大家可以把catalyst想象成僚机,加速一段感情,最后功成名退。 那么catalyst到底改变了什么?为什么它可以加速reaction?答案就是activation energy is decreased! 一般有两种常考的图来...
The rate of a chemical reaction refers to the speed with which reactants are converted to products, the substances formed from the reaction. Collision theory explains that chemical reactions occur at different rates by proposing that in order for a reaction to proceed, there must be enough energ...
The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the...
Which of the following is a chemical reaction? A. Melting ice B. Breaking a glass C. Rusting of iron D. Folding a paper 相关知识点: 试题来源: 解析 C。本题考查化学反应的定义。A 选项冰融化是物理变化,物质的状态发生改变但没有新物质生成。B 选项打破玻璃也是物理变化,只是物质的形状发生改变...
In a chemical reaction, the total mass of the reactants is equal to the total mass of the ___. A. products B. catalysts C. solvents D. reagents 相关知识点: 试题来源: 解析 A。在化学反应中,反应物的总质量等于产物的总质量,“products”是产物,“catalysts”是催化剂,“solvents”是溶剂,...
关于这种成比例的题目，成正比的写在分子上，成反比的写在分母上，一下子就一目了然了。
9. A catalyst is a substance that can speed up the rate of a chemical reaction without changing its own structure. 10. A black hole is a celestial body which has approximately the same mass as the sun and a gravitational radius of about3 km. Practice3: Complete the following definitions ...
a我们也不想跟一个不通情达理的客人合作 We do not want the visitor cooperation which is not reasonable with one [translate] a리콜! 리콜 인생 正在翻译,请等待... [translate] ais a chemical reaction that produces energy released in the form of light. In the presence of horseradish...