Innovative, chemistry experiments, suitable for junior high school students

Fountain Experiment. The basic principle of the fountain experiment is that the gas is very soluble in the liquid, and if there is enough pressure difference (negative pressure) in a short period of time, then after the piston is opened, the atmospheric pressure will press the liquid in the beaker into the flask, forming a fountain at the mouth of the needle-nose conduit.

To solve this problem, we think of several factors that affect air pressure. According to the Claberon equation: pv=nrt, p=(nrt) v (r is constant).

To make p smaller, you can change one of the variables n, t, v. So there are three ways to reduce the air pressure: reduce the amount of the gaseous substance (n); reduce the temperature of the gas (t); Increase the volume of the gas (v).

There are two ways to reduce the amount of gas in a substance: physical and chemical. The physical method can pump the gas away or physically dissolve it, and the chemical method can be chemical reaction or chemical dissolution; To reduce the temperature of the gas, we can use cold water or put a wet towel on the bottom of the bottle, or we can transfer the device to a lower temperature environment; The volume of the gas can be increased by increasing the temperature (e.g., pouring hot water or placing a hot towel at the bottom of the bottle) or changing the volume of the container.

The method of reducing the amount of gas substances by chemical methods is related to the solubility of the gas and the type of absorbent liquid. The size of the gas solubility has an impact on the formation of the fountain. For example, gases that are easily soluble in water, gases that are not soluble in water, and gases that are insoluble in water; Since their solubility in water is not the same, the pressure reduction is different, which is the key to whether the fountain can be produced and the size of the fountain.

The type of absorbent will also have an impact on the formation of the fountain, and whether different absorbent fluids can react with the gas and the solubility of the gas in it all determine the success or failure of the fountain experiment.

By analyzing the principles and conditions of the fountain experiment, we concluded that the key to the success of the fountain experiment was: the flask containing the gas must be dry, otherwise there will be liquid in the flask, which will leave air at the mouth of the bottle, and the fountain pressure formed is not large (the fountain is "weak"); The flask should be filled with gas; The flask must not leak air (the airtightness of the device should be checked before the experiment); The gas used can be dissolved in large quantities in the liquid used or the gas reacts quickly with the liquid.

1.A combination of fountains is formed.

1) NH3, HCl, SO2, NO2 can be combined with water to form a fountain.

2) The combination of acid gas and NaOH (AQ) can form a fountain.

3) The combination of organic gases and organic solvents can also form fountains.

4) O2, N2, H2 and other water-insoluble gases, designed to design certain experimental conditions to react them, can also form a fountain.

2.Calculation of fountains.

Based on the volume of liquid filled into the flask, the purity or average amount of gas contained in the flask can be calculated.

3.The design of the fountain.

The key is how to reduce the gas in the flask by a large margin.

It is divided into types such as experimental content innovation, experimental form innovation, experimental evaluation innovation and experimental course innovation.

1. Innovation of experimental content: improve and expand the traditional experimental content to make it more interesting and practical.

2. Innovation of experimental forms: explore different experimental forms and methods, such as gamification experiments, first-class mu belt experiments, etc., to improve students' participation and the effect of learning socks.

3. Innovation in experimental evaluation: change the traditional experimental evaluation method and adopt more scientific and objective evaluation methods, such as independent evaluation and interactive evaluation.

4. Innovation of experimental courses: Innovate from the design of the entire experimental course, pay attention to the integration of experimental links and theoretical knowledge, so that students can better understand the principles of chemistry and master experimental skills.

The innovation of chemistry experiments in middle school is carried out to enhance the understanding and mastery of chemistry knowledge among middle school students, improve their experimental skills and scientific literacy, and promote their interest and love for chemical science.

Whether 1+1 is necessarily equal to 2

If 1 volume of soybeans is mixed with 1 volume of mung beans, is the resulting volume equal to the sum of these two volumes?

Mixing 100 ml of water with 100 ml of alcohol, is the resulting volume equal to 200 ml?

Homemade simple water purifier.

Take an empty plastic beverage bottle, cut off the bottom, plug the bottle mouth with a single-hole plug with a catheter, turn the bottle upside down, and place the washed bulking cotton, gauze, activated carbon, quartz sand, small pebbles, etc. in layers from bottom to top in the bottle to get a simple water purifier.

Reaction of egg shell with acid.

Take a small glass, put in the washed crushed egg shells, then add some vinegar essence (the main ingredient is acetic acid) and immediately cover with a glass sheet dipped in clarified lime water. Watch carefully for what is happening. Based on experimental phenomena, it is speculated that the egg shell may contain some substances.

Homemade soda. Add 2 tablespoons of sugar and appropriate amount of fruit juice to a 500 ml bottle, add about g of baking soda (sodium bicarbonate), pour in cold boiled water, add about g of citric acid, immediately tighten the cap, shake well, and put in the refrigerator. Half an hour later, you'll be ready to drink a cool and sweet soda.

Deliquescence of coarse salt.

Use moon flowers, carrots to make acid-base indicators, crush and soak in alcohol to make a clear liquid.

Put sucrose in a beaker and add a little concentrated sulfuric acid!!

If you want to innovate, you have to think for yourself.

There are many chemistry experiments suitable for junior high school students, and in the small family experiment, ** candle burning experiment, according to the content of the textbook, this experiment requires a beaker (replaced by a glass), a candle, a match, a knife, a glass piece, a small bowl, and water. Light the candle and observe the phenomenon of flame layering, the candle is cut with a knife to verify the hardness of the candle, the candle floats on the surface of the water to verify the density of the candle.

The cover glass above the flame, with water droplets, proves that the candle burns with water, collects the gas produced by the combustion, passes to the flame, and the flame is extinguished, proving that the candle burns to produce a gas that does not support combustion.

It is also possible to do salt solubility experiments.