Lecture 02 Exploration of Candle Burning and Inhalation and Exhaled Gas Experiments
02 Lecture On candle burning and inhalation of exhaled gas experiments
Mind map
Knowledge combing
Knowledge point one scientific inquiry
(1) Chemistry and experimentation
Chemistry is an experiment-based science, and many of the major discoveries and research results of chemistry are obtained through experiments.
(2) Scientific inquiry
Experimentation is an important way to learn chemistry. Through experiments and observations, recordings and analyses of experimental phenomena, it is possible to discover and verify the principles of chemistry, learn the methods of scientific inquiry and acquire new chemical knowledge. The basic aspects of scientific inquiry: asking questions→ conjectures and hypotheses→ formulating plans→ conducting experiments→ collecting evidence→ explaining and discussing→ reflecting and evaluating→ expressing and communicating, etc.
(3) Observe and describe phenomena
Pre-reaction: Observe the color and state of the reactants. During the reaction, observe the conditions required for the reaction to occur (whether heating or other additional conditions are required).
Reaction: The phenomenon that occurs (whether there is precipitation, gas generation, whether there is luminescence, heat or color change).
After the reaction: Observe the color and state of the product.
The example is concise
1. There is a package of black powder on the experimental table, in order to verify whether the powder is iron powder, some students proposed to put the magnet on top of the powder. This belongs to scientific inquiry ( )
A． Conjecture hypothesis B. Gathering Evidence C. Design Experiment D. Conclusions
Answer: C
2． The most basic research methods and means that are indispensable and basic in chemical research are ( )
A． Learning from previous achievements B. Research C. Lab D. illation
Timely drills
1． The appearance of the dollar coin has a silvery-white metallic luster, and some students think it may be made of iron. During the discussion, Student A said: "We can first take the magnet to suck it up", as far as this process is concerned, it belongs to scientific inquiry ( )
A． Proposing Hypothesis B. Observation of the phenomenon C. Design Experiment D. Draw conclusions
2． After the physical education class shot put throwing activity, the students discussed the materials for making the "lead ball", and some students thought that the "shot put ball" was made of iron, and borrowed a magnet from the laboratory to suck it. The process of "sucking in" is part of scientific inquiry
A. Ask the question B. Make a conjecture C. Conduct an experiment D. Draw conclusions
【Answer】Borrowing a magnet from the laboratory to suck it up belongs to the experiment in the scientific inquiry link, so C is correct;
Knowledge Point Two An inquiry into candles and their burning
Exploration Experiment 1 An inquiry into candles and their burning
1. Background: Carbon dioxide gas can make the clarified lime water turbid
2. Experimental process:
(1) Before ignition: observe the color, state, shape, hardness, odor, density, solubility, etc.
(2) Light a candle:
(1) Observe how many layers of flames are divided, which layer is the brightest and which layer is the darkest?
(2) Put the matchstick flat into the flame for one second, take it out and observe, what can explain the problem?
(3) What is the phenomenon of covering the flame with a dry beaker? What does that mean?
(4) What is the phenomenon of injecting clarified lime water? What does that mean?
(3) Extinguish the candle: can you light white smoke?
3. Phenomenon recording:
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Explore the steps
Observation and description of phenomena
Before igniting
When burning
After extinguishing
4. Characteristics of Chemistry Learning:
(1) Pay attention to the properties of the substance, such as color, odor, state, hardness, density, melting point, boiling point, solubility, etc.
(2) Pay attention to the changes of substances, such as the melting, solidification, phenomenon of burning and the generation of new substances when candles are melted.
(3) Pay attention to the change process of matter and its phenomena, and carefully observe and describe the phenomena of matter before, during and after change, compare and analyze to draw correct conclusions.
1. In the following description of paraffin properties, the error is ( )
A． Paraffin wax is a colorless, odorless, and hard solid B. Paraffin wax is insoluble in water and has less density than water
C． Paraffin has a low melting point and is easily melted into wax oil when heated D. Paraffin wax is flammable and when burned there is carbon dioxide and water formation
Answer: A
2. The narrative of the experimental phenomenon of candle nature inquiry is wrong ( )
A． The gas generated after the candle is burned can make the clarified lime water turbid
B． The candle burns at the same time as the melting process
C． Use a match to light the white smoke when the candle is just extinguished, and the candle can be re-burned
D． Candles generate carbon dioxide and water when burned in the air
3. A classmate placed the candle in a gas collection bottle filled with oxygen to burn, and found that there was water mist on the bottle wall, and the hand that touched the bottle wall felt hot. From this, he came to the following conclusion, what you think does not fit this experiment is ( )
A． Candle burning releases heat B. Candles burn with carbon dioxide production
C． Candles burning have water generated by D. Candles burn in oxygen
Answer: B
4. In the following experiments on candle burning, the description of the experimental phenomenon is incorrectly ( )
A． The candle flame is gradually extinguished in Experiment 1 B. Experiment 2 There is no significant change in the surface of the white porcelain plate
C． Experiment 3 The matchstick in the outer flame section turns black first D. Experiment 4 There is water mist generating on the inner wall of the beaker
5. Conducting experiments of scientific inquiry, what does not reflect the characteristics of the discipline of chemistry is ( )
A． Properties of Substances of Concern B. Focus on the use of substances
C． Changes in substances of concern D. Pay attention to the process and phenomenon of material change
1． In the following description of paraffin properties, the error is ( )
A． Paraffin wax is a colorless, odorless and hard solid
B． Paraffin wax has a low melting point and is easily melted into wax oil when heated
C． Paraffin wax is insoluble in water and has less density than water
D． Paraffin wax is flammable, glowing and exothermic when burned
2． The correct description of the phenomenon when a candle burns is ( )
A． Carbon dioxide and water are generated when the candle burns
B． Candles burn to release heat and emit a yellow flame
C． The inside of the dry, cold beaker that shrouds the flame of the candle has white smoke on the inner wall
D． The carbon dioxide generated by candle combustion can make the clarified lime water turbid
3． A classmate conducted the following investigation into candles (the main ingredient is paraffin wax) and their combustion. Please fill in the following fields:
(1) Take a candle, cut a small piece with a knife, put it in the water, and the candle floats on the surface of the water. Conclusion: The hardness of paraffin wax is ____________
(2) Put a matchstick in the flame of the candle (pictured) for about 1 s and take it out, and you can see that the ____________ Conclusion: The ______
(3) Cover a dried beaker above the candle flame, and __________ Remove the beaker and quickly pour a small amount of clarified lime water into the beaker, shaking, and the clarified lime water becomes ____________ Conclusion: When the candle burns, a ______
【Answer】(1)Small Small Insoluble (2)a Outer flame (3) Water mist Turbid water and carbon dioxide Chemistry
4. Answer the questions according to the image below
(1) After the candle is lit, the number of electronic scales is gradually reduced. The reduced mass of the candle ________
(2) Quickly hold the burning candle with a glass and make the mouth of the cup always submerge in water, and finally the liquid level in the cup is ______
[Answer] (1) is less than (2) higher
5. The candle (sufficient amount) is burned in the closed device of Figure A until extinguished, and the change of oxygen content in the bottle is measured by the instrument as shown in Figure B. The following judgment is correct ( )
A. The total mass of the substances in the process is decreasing B. When the oxygen concentration is less than a certain value, the candle cannot burn
C. Only carbon dioxide gas remains in the bottle after the candle is extinguished D. There is only oxygen in the device before the candle burns
【Answer】 B
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