The chemical equation for potassium permanganate to produce oxygen: 5 details that you thought would be wasted as soon as you made it

A nearly forgotten purple history

Turn back time1659German chemistJohn Glauber(Johann Glauber) tinkering with a black mineral in the lab.pyrolusite(The main ingredient is manganese dioxide), accidentally discovered a mysterious metallic lusterDark purple crystal。

He didn't know it at the time, but this is what became famous laterpotassium permanganate(Commonly known as "ash manganese oxygen"Or"PP powder"). until more than a century later1817The French chemistP.v. Chevillot and W.F. Edwards Just passed for the first timemanganese dioxide、potassium hydroxideandpotassium nitrateMixing and melting, then hydrolyzing and transforming, truly "tamed" this purple substance.

From then on, the "purple goblin" of potassium permanganate officially entered the stage of chemical history. It exudes a strongOxidationIt can not only disinfect wounds, but also purify water. And it is the classic that has allowed it to enter thousands of high school and university laboratoriesChemical equation for the production of oxygen from potassium permanganate。

The core equation: Make it clear in one sentence

So this is how it all started.Chemical equation for the production of oxygen from potassium permanganate：

2KMnOじ= = ¦ = = KMnOじ+ MnOλ + Oλ ↑

When the two-molecule potassium permanganate reagent (KMnO) is heated, it decomposes into potassium manganate and manganese dioxide reagent, and releases a molecule of oxygen.

From Glauber's chance discovery of this purple crystal in the 17th century, to chemists figuring out its temper in the 19th century, to today's "compulsory course" for every beginner in chemistry -Preparation of oxygen from potassium permanganatechemical equationIt has been written in countless chemistry textbooks around the world.

You know the equations by heart.But as soon as you get started, it will be uselessBelow this5 detailsIt is the focus of the teacher's repeated knocking on the blackboard, and it is also the most common deduction point for laboratory exams - they are all hidden inChemical equation for the production of oxygen from potassium permanganateBehind the back, the light back formula cannot be seen.

Detail 1: Cotton ball - the "goalkeeper" of the test tube mouth

operationAfter installing the potassium permanganate reagent, be sure toTest tube mouth plug ball of cotton。

Why is that?: To prevent those fine purple powders from rushing in with the airflow when heatedclogged catheterOr contaminate the oxygen collected.

consequences: If there is no plug, the gas will be impure at light, and the catheter will be blocked at heavy, and the experiment will fail. This is the executionChemical equation for the production of oxygen from potassium permanganateThe most easily overlooked first step.

Detail 2: The mouth of the test tube is tilted slightly downward - don't let the condensation "fry" the test tube

operationWhen fixing the test tube, ensure thatThe mouth of the test tube is slightly lower than the bottom of the test tube。

Why is that?When heated, the moisture in the drug or the water vapor generated by the reaction will condense into water at the nozzle. If the test tube mouth is facing up or horizontal, the condensed water willbackflowTo the bottom of the hot test tube.

consequencesThe bottom of the hot test tube meets cold water.It exploded on the spot.This is the first red line for experimental safetyChemical equation for the production of oxygen from potassium permanganateI can't write it here, but I must understand the key to practical operation.

Detail 3: Preheat evenly first - don't come up and "collect juice on fire"

operationAfter lighting the alcohol lamp, first hold the lamp under the test tubeMove back and forthLet the test tubeuniform heating(Approximately 30 seconds), and then heat the medication area again.

Why is that?The test tube is made of glass, and local sudden heating can lead to uneven heating.

consequencesAt best, the test tube will burst, and at worst, the experimenter will be injured. This step cannot be rushed.Chemical equation for the production of oxygen from potassium permanganateYou also need to leave enough time for the test tube to warm up.

Detail 4: Wait for the bubbles to come out evenly in a row - don't collect "fake oxygen"

operationWhen collecting oxygen by drainage method, wait for the bubbles at the catheter portContinuous and uniformAfter the ground appeared, he began to collect.

Why is that?: The bubbles that first came out were in the test tubeAir expands when heatedRunning out, not oxygen.

consequences: Collect it directly without waiting. What you collect is a bottle of "air + oxygen" mixture, and the wooden strip with Mars can't reignite at all. This operation pit, withChemical equation for the production of oxygen from potassium permanganateIt has nothing to do with itself, but it determines success or failure.

Detail 5: Remove the duct first, then turn off the light - don't let the water "inhale"

operationAfter the experiment is over, the first action is to putThe conduit is removed from the sink, and then againTurn off the alcohol lamp。

Why is that?: If the light is turned off first, the temperature in the test tube drops sharply, the air pressure decreases, and the water in the sink will besuck backInto a hot test tube.

consequencesHot tube meets cold water, againburstIn this order, exams are required, experiments are required - butChemical equation for the production of oxygen from potassium permanganateLi can't write, it's all up to the teacher to knock on the blackboard repeatedly.

Detail 6 (Hidden Pass): How does potassium permanganate usually "raise"?

After the experiment is done, you can just stuff the remaining bottle of potassium permanganate into the cabinet? This is a"Grumpy", will not be maintained, and you will find when you use it next time - not enough gas production, wrong color, and even agglomerated. Below is potassium permanganateSave the "Four No Principles"：

① Don't see the light
Potassium permanganate is sensitive to light and decomposes slowly after long-term exposure to light.standard operation: useBrown reagent bottlePack, putAvoid lightIn the reagent cabinet. If it is packed in a transparent reagent bottle, either stick black shading paper or wrap the whole bottle with aluminum foil.

② Do not get wet
Although potassium permanganate does not "rush to absorb water" like sodium hydroxide, it still has a certain degree of moisture absorption. After being damp, it is not only inaccurate to weigh, but also easy to "splash" when heated (wet powder splashes when heated).save pointsCover the bottle immediately after use and place in a dry place.

③ Do not be next to "flammable and explosive molecules"
Potassium permanganate is a strong oxidizing agentorganic matter(Paper, ethanol, glycerin),reducing agent(Sulfides, sulfites),Acids(Especially concentrated sulfuric acid) put together, light will deteriorate, heavy will deterioratefire explosion。Iron LawStore separately, away from the organic reagent cabinet.

④ Do not store for a long time without inspection
Even if stored properly, potassium permanganate standard solution is recommendedmonthly recalibrationOnce; solid reagent recommendationsCheck once every six months- If you find severe agglomeration, darker color or brown spots (MnO 2O) on the surface, it means that it has been partially decomposed, and it is recommended to replace it with a new batch.

💡 The most easily overlooked one for beginners: Don't open the bottle directly for the newly bought potassium permanganate. Observe the color first - it should be bright purple-black with metallic luster. If it is dark and black, it means that the storage time is too long or the storage conditions are unqualified. Contact the supplier directly to return it.

The scientific grain official said that the quality of the reagents is stable and the experimental error is small

From Glauber's accidental discovery in 1659 to the standardized operating procedures in laboratories today,Chemical equation for the production of oxygen from potassium permanganateAfter more than 300 years, the light of science still shines brightly.

However, no matter how standard the operation is, it cannot withstand unreliable reagents - potassium permanganate is damp, and the gas production is not enough; the purity is not enough, and the experimental phenomenon is not obvious; if it is not stored properly, the next batch of experiments will be directly "overturned". At this time, a reliable reagent platform is the "ballast stone" for your successful experiment.

Scientific Grain Officer- One-stop shopping platform for digital intelligence of scientific materials, with super1 million speciesFine chemicals database, fromHigh purity potassium permanganateTo various specifications of experimental supplies, one-stop supply. "Intelligent manufacturing is only standard, and experiments are not too embarrassing", Solve the quality hidden dangers of the reagent at the source, and you can spend all your energy on accurate operation. After all, write it skillfullyChemical equation for the production of oxygen from potassium permanganateYou must also have a bottle of reliable reagents in hand to have confidence in the experiment.

Scientific Grain OfficerWell said.The quality of the reagent is stable and the experimental error is small. Hope next time you faceChemical equation for the production of oxygen from potassium permanganateNot only did he remember the formula, but he was also able to handle every operation detail calmly - including how to "raise" the bottle of purple powder after the experiment.

After all, experiments can be rigorous, but preparation must be unhurried - this is what science should be like.