The air density is 1.293g/l and the oxygen density is 1.429g/l. According to the volume fraction of oxygen in the air, what is the mass fraction of oxygen in the air?

The air density is 1.293g/l and the oxygen density is 1.429g/l. According to the volume fraction of oxygen in the air, what is the mass fraction of oxygen in the air?

The volume content of oxygen in the air is about 21%, so the mass fraction of oxygen in the air is:
21％*1.429/1.293＝23.2％

Under the known standard conditions, the air density is 1.293 g / L and the oxygen density is 1.429 g / L. the mass fraction in the air is calculated according to the volume fraction of oxygen in the air

Density = mass / volume, calculate the volume of oxygen divided by the volume of air

Please design a group of comparative experiments by chemical method and fill in the experiment report. Experiment Name: verify that the density of oxygen is higher than that of air. Experiment purpose: verify that the density of oxygen is higher than that of air by comparative experiments based on the properties of oxygen. Experimental equipment: ① 2 gas collecting cylinders filled with oxygen and covered with glass flakes; ② 1 wood strip; ③ matches; ④ Alcohol lamp experiment report: & nbsp; & nbsp; & nbsp; & nbsp; real & nbsp; & nbsp; Test & nbsp; & nbsp; over & nbsp; & nbsp; Cheng & nbsp; & nbsp; & nbsp; & nbsp; experimental phenomenon & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; Solution & nbsp; & nbsp; & nbsp; & nbsp; explanation______ &Conclusion: under the same conditions, the density of oxygen is higher than that of air

Take a bottle full of oxygen, put the bottle mouth up, remove the glass piece, after a certain period of time, put the wooden strip with Mars into the bottle. Take another bottle full of oxygen, put the bottle mouth down, remove the glass piece, after the same period of time, put the wooden strip with Mars into the bottle, remove the glass piece, after the same period of time