Liquid nitrogen has a lower boiling point than liquid oxygen, resulting in what evaporates from the

Because liquid nitrogen has a lower boiling point than liquid oxygen, liquid nitrogen becomes a gas first, and liquid oxygen is still liquid, so liquid nitrogen evaporates from liquid air first.

Boiling point of liquid nitrogen:

Boiling point of liquid oxygen: °C

As long as the temperature is controlled in between, the liquid nitrogen can be completely separated from the liquid oxygen.

However, due to the low temperature of liquid nitrogen and liquid oxygen, care should be taken to avoid frostbite when operating. **Exposure to liquid nitrogen can cause frostbite. If the nitrogen produced by vaporization at atmospheric pressure is excessive, the partial pressure of oxygen in the air can drop, and in extreme cases, it may cause hypoxic asphyxiation.

Treatment of liquid nitrogen poisoning.

First aid measures. **Contact: If you have frostbite, seek medical attention**.

Inhalation: Quickly remove from the site to fresh air. Keep your airways open. If you have difficulty breathing, give oxygen. If breathing stops, artificial respiration is performed immediately. Medical treatment.

Fire protection measures. Hazard characteristics: In case of high heat, the internal pressure of the container increases, and there is a risk of cracking and **.

Harmful combustion products: Oxides of nitrogen.

Fire extinguishing method: This product is non-combustible. Keep the container cool in the fire with mist water. Spray water in the form of a mist to accelerate the evaporation of liquid nitrogen, but do not shoot a water gun into liquid nitrogen.

Emergency response. Emergency treatment: Quickly evacuate the personnel from the leakage and pollution area to the upwind place, isolate them, and strictly restrict access and access.

Emergency responders are advised to wear self-contained positive pressure breathing apparatus and cold-proof clothing. Do not come into direct contact with spills. Cut off the source of the leak as much as possible.

Use an exhaust fan to send the leaked air to an open area. Leaking containers should be properly disposed of, repaired, and inspected before use.

Liquid nitrogen laxative treatment method.

When the concentration of inhaled nitrogen is not too high, the patient initially feels chest tightness, shortness of breath, and weakness; This is followed by irritability, extreme excitement, running around, shouting, trance, and unsteady gait, which is called "nitrogen tincture", and can enter a state of lethargy or coma. When inhaled at high concentrations, patients can quickly fall unconscious, die due to respiratory and cardiac arrest.

1. Quickly evacuate personnel from the leakage and pollution area to the upwind place, and set up an isolation area to strictly restrict access and access.

2. Notify the fire department and related units.

3. Emergency responders wear self-contained positive pressure respirators, cold-proof clothing, and cold-proof gloves.

4. Avoid leaking liquid into the basement or other enclosed working space, and notify the relevant departments immediately if it cannot be avoided.

5 Do not come into direct contact with spills.

6 Cut off the source of the leak as much as possible.

7 You can use mist water spray to accelerate the evaporation of the liquid, but do not shoot the water gun into the liquid.

8. Prevent gas accumulation in low recesses, and use an exhaust fan to send the leaked air to an open place.

9 Personnel are prohibited from staying in low-lying or downwind areas.

The density is low and the oxygen comes out

When the temperature drops below the boiling point of nitrogen, the air is liquefied (oxygen is liquefied first).

When the liquid air at low temperatures is heated to the boiling point of nitrogen, the nitrogen begins to vaporize, but at this point the temperature is below the boiling point of oxygen, and the oxygen remains liquid. Oxygen can only be vaporized if it continues to heat up so that the temperature is higher than the boiling point of oxygen.

Therefore, it is the liquid nitrogen that gasifies first.

Evaporation has nothing to do with the boiling point, it can evaporate at any temperature, for example, the boiling point of water is 100 degrees Celsius, the water you splash on the ground will evaporate, but the temperature does not reach the boiling point of water, evaporation is related to many factors, such as ambient temperature, air flow...

Helium is the first to be separated.

When the temperature is below degrees, all three gases are liquid.

When the temperature rises to degrees, helium changes from liquid to gaseous, when the first separation temperature rises to -196 degrees, liquid nitrogen becomes gaseous, and when the separation temperature rises to -183 degrees, liquid oxygen changes to gaseous state, and finally separated.

When the temperature of liquid air rises, the lower the boiling point, the more it escapes first, the higher the boiling point, the later it escapes Liquids with low boiling points reach the boiling point first and vaporize first Helium has a low boiling point and vaporizes first The order in which they escape is helium, nitrogen, and oxygen

Therefore, choose D

A ammonia Ammonia has a high boiling point and will be the first to liquefy, reaching -33 and starting to liquefy. Oxygen needs to be liquefied until -183, and nitrogen is not liquefied until -196, so it is ammonia. ,3,It is known that the boiling points of liquid oxygen and liquid nitrogen at standard atmospheric pressure are -33, -183 and -196

If these gases are extracted using liquid air, the first thing to be liquefied is ammonia, nitrogen and oxygen.

Summary. Because the boiling point of nitrogen is lower than that of oxygen, when the temperature reaches the temperature of nitrogen boiling point but has not yet reached the temperature of oxygen boiling point, then nitrogen will evaporate first.

The boiling points of nitrogen and oxygen are -196 and -183 °C respectively, so it is clear that nitrogen is lower than that of oxygen, but why does nitrogen evaporate before oxygen during fractionation?

Because the boiling point of nitrogen is lower than that of oxygen, when the temperature reaches the temperature of nitrogen boiling point but has not yet reached the temperature of oxygen boiling point, then nitrogen will evaporate first.

What we assume is that the temperature starts to rise from a very low temperature, so it must be that the nitrogen will evaporate first.

But since the temperature of our daily life is much higher than the boiling point of the two of them, both are gases in the air.

Since the air contains about 21% oxygen, it is the best cheap and readily available raw material for industrial oxygen; The industrial oxygen production adopts the method of separating liquid air: pressurized at low temperatures to convert the air into liquid air and then evaporate; Since the boiling point of liquid nitrogen is lower than that of liquid oxygen, nitrogen first evaporates from liquid air and the rest is mainly liquid oxygen; There is no new substance formed in the whole process of positive grasping, which is a physical change In addition to oxygen, the oxygen obtained by the industrial lifting model also contains nitrogen and other gases, which is a mixture; The physical property that different substances have different boiling points is exploited

Therefore, the answer is: physical low first evaporates oxygen from liquid air mixed with physics.

Untie; Because liquid nitrogen has a lower boiling point than liquid oxygen, nitrogen evaporates from liquid air first;

So the answer is: low, nitrogen.

Since most of the air is nitrogen and oxygen, most of the remaining gas is oxygen, and according to the nature of oxygen to support combustion, after a while, the wooden strips do not go out but burn more vigorously, so the answer is: O2

After evaporation, and O2

Can support combustion

In industry, the boiling point of liquid oxygen and liquid nitrogen is different, and the method of distillation is used to produce oxygen.

Through the distillation column, the liquid air is distilled by using the different boiling points of liquid oxygen and liquid nitrogen, and the nitrogen gas that comes out of the distillation column becomes dirty nitrogen. What is obtained below is pure liquid oxygen.

Industrially, the boiling points of liquid oxygen and liquid nitrogen are different, and oxygen is produced by separating liquid air.