1, production of color thermometer
Experimental principle
Cobalt hydroxide will show different colors when it loses water gradually when heated, so it can change according to the temperature.
The change of color is made into a thermometer.
Experimental steps and phenomena
Adding 95% ethanol and a small amount of red cobalt chloride crystal (CoCl2 6H2O) into the test tube,
Dissolved by oscillation, it is purple-red at room temperature, and its color is blue-purple to pure blue with the increase of temperature when heated.
2. soda-acid fire extinguisher
Experimental steps and phenomena
(a) As shown in the figure below, use a large bottle with a single-hole rubber stopper and insert the glass tube. Put it in a bottle
Add some sodium bicarbonate solution, take a test tube that can be put into a bottle and fill it with concentrated hydrochloric acid. Take your time.
Put it in a bottle to make the test tube stand upright, and put a rubber stopper with a glass tube on it. Please turn the bottle upside down when using the fire extinguisher.
Aim the glass nozzle at the flame. Watch out! Don't point the nozzle at others or yourself.
(b) adding a detergent to the acid to produce a covering foam. Aim the bottle at the flame, quickly.
When the bottle is turned upside down, the violent reaction produces a lot of carbon dioxide, and then the pressure of the gas will press the liquid out of the nozzle and destroy it.
It's on fire.
3, wand lighting
Can a glass rod be used instead of a match to light an alcohol lamp?
Experiment: put a small amount of potassium permanganate crystal on the mirror (or glass), drop 2 or 3 drops of concentrated sulfuric acid on potassium permanganate, dip it with a glass rod, and touch the wick of the alcohol lamp, and the alcohol lamp will light up immediately.
4. Build an "underwater garden"
Sodium silicate (Na2SiO3) was dissolved in water to make water glass with 40% solute mass fraction, and then it was gently mixed with sodium silicate.
Crystal grains of salts, such as chlorides of cobalt, iron, copper, nickel and lead, sulfates of aluminum, iron, copper and nickel, cobalt,
Nitrates of iron, copper and nickel, added to water glass (be careful not to shake), are colorful "flowers".