How to get oxygen

Today the issue of ecology comes to the fore. But a healthy ecology is impossible without oxygen. It is he who is the main building block of life on the planet Earth. In addition, oxygen is often involved in many chemical reactions. Let's look at how to get oxygen in a chemical laboratory.

Today the issue of ecology comes to the fore. But a healthy ecology is impossible without oxygen

To obtain oxygen, strengthen the refractory glass tube on a tripod and add 5 g of powdered nitrate (potassium nitrate KNO3 or sodium nitrate NaNO3) to it. We put a cup of refractory material filled with sand, as this glass often melts and a hot mass flows out. Therefore, we will keep the burner on heating when heated. When we strongly heat the saltpetre, it will melt and oxygen will be released from it (we will find it with the help of a smoldering ray - it will ignite in a test tube). In this case, potassium nitrate will pass into the nitrite KNO2. Then we throw a piece of cuttings sulfur in the melt with crucible forceps or tweezers (never hold the face above the test tube). The sulfur will ignite and burn with the release of a large amount of heat. The experiment should be carried out with open windows (due to the resulting sulfur oxides).

The process proceeds as follows (heating):

2KNO3 → 2KNO2 + O2

You can get oxygen by other methods. Potassium permanganate n4 gives off oxygen under heating and thus transforms into manganese oxide (4):

2KMnO4 → MnO2 + K2MnO4 + O2.

Of 10 grams of potassium permanganate, about a liter of oxygen can be obtained, which means that two grams are enough to fill with oxygen five standard-size tubes.

A certain amount of potassium permanganate is heated in a refractory tube and we catch in the test tubes evolved oxygen using a pneumatic bath. Crystals, cracking, are destroyed, and often some of the dust-like permanganate is entrained along with the gas. The water in the air bath and the discharge tube in this case will turn red.

In large quantities, oxygen can also be obtained from hydrogen peroxide (peroxide) H2O2. Hydrogen peroxide is not very stable. Even when standing in the air, it decomposes into oxygen and water:

2H2O2 → 2H2O + O2

Obtaining oxygen can be significantly faster if you add to the peroxide a little manganese dioxide MnO2, active coal, metal powder, blood (curled or fresh), saliva. These substances act as catalysts.

We can see this if we put about 1 ml of hydrogen peroxide with one of the substances mentioned in a small test tube, and the presence of excreted oxygen is established with the help of a probe with a laser beam. If an equal amount of animal blood is added to a 5 ml 3% hydrogen peroxide solution in a beaker, the mixture will foam strongly, the foam will solidify and swell as a result of the release of oxygen bubbles.

Catalysts increase the rate of reaction of the chemical process and do not themselves expend. Ultimately, they reduce the activation energy necessary to excite the reaction. But there are also substances acting in the opposite way. They are called negative catalysts or inhibitors. For example, phosphoric acid prevents the decomposition of hydrogen peroxide. Therefore, the commercial hydrogen peroxide solution is usually stabilized with phosphoric or uric acid. In living nature, so-called biocatalysts (enzymes, enzymes, hormones) participate in many processes.