How to find the amount of oxygen in a room!?

Question

The room is sealed and there is nothing in the room so oxygen cant be gained or lost.

Answer 1

Use PV = NRT

That is if you know temp, press, and dimensions of room.  Air is 20.9% O2.

You could also do some oxygen consuming reaction and weigh the products; subtract wt of reactants and difference is O2. But the room would implode when you reduced the pressure by 1/5....

Answer 2

1) calculate the volume of the room by measurement. Say the room is 10m x 10m x 10m = 1000m³  

2.) Air contains roughly (by molar content/volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor.

3) Therefore your room will contain 209.5m³ of oxygen.

4) If you want the mass of oxygen, easiest way is to know that 22.4 litres of oxygen at STP has a mass of 32g. You have 209,500 litres of O2. Therefore you will have :

(209500/22.4)*32 = 299,285.7g of oxygen

OR 299.3kg oxygen in the room.

Answer 3

Oxygen in air

Science at Home

Materials : Two magnets., Glass flask, Glass bottle,  Paper.

   Compounds : Water ,Iron powder.  

Procedure

     1. Fill half of the bottle with water.

     2. Cover the magnet surfaces with iron powder.

     3. Place the magnet with the iron powder inside the glass bottle.

     4. Outside the bottle, with the help of another magnet, hold the magnet with iron in the top off the bottle. (the magnets shouldn't be in contact with water)

     5. Turn the glass bottle upside down inside the glass flask, submerging part of it.(now we have a closed system inside the bottle)

     6. Mark the initial water level in the inverted bottle.

     7. Verify how the water level is changing periodically during the next 24 hours. What happens?  

Why?

In this experiment you can observe that the water level inside the bottle arises about 20% of the air total height. Inside the inverted bottle we have air, a magnet and iron powder. The air is constituted by nitrogen (79%), oxygen (20%) and other gases (1%). The iron oxidizes (formation of iron oxide) in the presence of an atmosphere that contains oxygen. In the present experiment, the iron powder in the magnet reacts with the oxygen arising the water level. That happens because the product of the reaction between the iron and the oxygen is solid. As we know, a solid occupies less volume comparatively with a gas. At a certain moment, the level of the water stays unaffected because the iron oxidation ceases due to oxygen lack.

http://scienceathome.cienciaviva.pt/oxid...