Oxygen

Oxygen content in the air Objective: To measure the proportion of oxygen in the air and the proportion of oxygen in the expiration Hypothesis: The amount of oxygen in the air is greater than the amount of exhaled breath from the human body. Procedure: Wash hands to remove grease. Take two samples of steel wool (0.7 g each), put a wool sample in 35 mL vinegar solution for 1 minute, remove wool from solution, shake to remove vinegar, Put the steel wool into the syringe. The plunger was placed in a syringe 28 mL mark and placed in a 250 mL beaker filled with a syringe slightly. Pull the plunger until water reaches the 0 mL mark record and observe the water every 3 minutes.

Oxygen isotopes are used as an ancient thermometer. Oxygen exists in two forms, oxygen - 16 and oxygen - 18. They bind to calcite skeletons of marine organisms at different rates, depending on water temperature, more oxygen-18 at low temperature, and higher oxygen-16. At the bottom of the floor 25 where the main mass disappears, the oxygen isotope ratio changes abruptly, showing a global temperature rise of 6 ° C. This may not sound so much, but it will have a major impact on the ecology of the world. Climatologists have recently been extremely excited about half the world temperature rise.

After the appearance of the photochemical system II, the oxygen level rises. Dissolved oxygen in the sea increases with oxygen in the atmosphere. This is sometimes called oxygen genocide. Oxygen is a very good electron acceptor, which brings about a great destructive effect on the living body. Many bacteria are anaerobic and die almost immediately when oxygen is present. Other organisms like animals have a special way to avoid damage of cells caused by this element (in fact it is necessary for it to survive). First, when oxygen started to accumulate in the environment, it was neutralized by already existing substances. Iron present in high concentrations in the ocean is oxidized and precipitates. Evidence of this situation can be seen in the iron band during this period, a layer of iron deposited on the ocean floor. As one geologist said, "The world is rusty." After all, it will be high enough to be dangerous to life.