The concept of catalysts
There are three cognitive levels for mastering basic concepts:
1. memory characterization (retentive mechanical memory, comprehensible encoded memory, methodical meaningful memory)
2. linguistic representational integrity (expressed in words, simple sentences, complete units of thought)
3. simple reasoning (one-step thinking, two-step thinking, multi-step thinking)
Our instruction should achieve the second level for all levels of students and do our best to pursue reaching the third level.
In order to reach the third level, I summarize a basic idea: contextualization, de-contextualization, and re-contextualization.
1. Introduce concepts with good contexts; (contextualization)
2. extract chemical concepts from the situation and student activities (de-contextualization)
3. use concepts to solve real problems (re-contextualization)
Allow students to learn deeply in interesting contexts, reason with evidence in decontextualized experiments, cultivate students’ sense of scientific inquiry and innovation, and cultivate the spirit of science and social responsibility in the process of re-contextualization.
1. What is elephant potion?
2. What is a catalyst? What is the catalyst used here?
3. Why did the catalyst produce a lot of bubbles at once?
4. Why is there white gas, is it because of exothermic heat?
5. What is the black substance on the paper? (actually purple-black in color)
6. Why did the wooden bar rekindle at first, but when it was stretched out later, it just glowed and did not rekindle?
What is Elephant Potion?
Elephant’s Potion is hydrogen peroxide.
A liquid that spontaneously produces oxygen at room temperature is hydrogen peroxide, which reacts to produce water and oxygen, and manganese dioxide acts as a catalyst for the hydrogen peroxide reaction.
What is a catalyst and why does adding a catalyst produce a lot of foam?
About catalyst
(1) Catalytic action is divided into positive and negative catalysis, and positive catalysis speeds up the rate of reaction;
(2) Catalyst A will be added to the reaction to produce intermediate products, and the intermediate products will be converted into substance A. Therefore, the chemical properties and quality of the catalyst do not change before and after the reaction;
(3) In the reaction due to a variety of factors, part of the catalyst will lose activity, so the catalyst in the actual chemical production is subject to loss.
Translated with DeepL.com (free version)
