FIM O,N (6)

Nitrogen is

the 5th most abundant element in the universe

How many nitrogen isotopes are there?

4

Physical properties of nitrogen

decent diffusability
decent heat conductivity
less soluble in water than oxygen

How can nitrogen be produced

fractional distillation of air

membrane process for separation from oxygen and water

pressure swing adsorption process

thermal decomposition of sodium azide (rare)

The purity of nitrogen by fractional distillation is up to

99.99999%

The purity of nitrogen by membrane process is up to

99%

The purity of nitrogen by adsorption process is up to

99.9%

Which production method is of increasing importance due to lower price?

Pressure swing adsorption process

What is the Linde process?

a way to liquefy gases

Why is Linde process necessary?

production of liquid nitrogen and oxygen

medical oxygen supply

industrial gas supply

cryogenics

What is fractional distillation of air?

a process used to separate components of liquefied air based on their different boiling points

Steps of fractional distillation of air

air is filtered through to remove dust and impurities

air is cooled under high pressure until liquid (-200 degrees)

liquefied air is slowly warmed up in a fractioning column

as the temperature rises, gases boil off and condense (most volatile travels the furthest)

In which order are gases collected in fractional distillation of air?

Nitrogen from the top
Argon
Oxygen

Why is nitrogen gas used?

inert and inexpensive

Applications for gaseous nitrogen

shielding gas (welding, lamp filling)

propellant (neutral to climate)

package gas (transport, sample storage)

tire gas (airplanes, tricks, F1 cars)

food additive (gas for whipped cream, pressure stabilisation of beverage cans)

Applications for liquid nitrogen

cryo technology

high temperature super conductor (NMR, ESR)

hardware overclocking (extreme cooling of central processing units)

glass transition (cooling of polymers below their glass transition temperature, therefore removal of cable insulation)

What is the main drawback of using liquid nitrogen in cryo technology?

Leidenfrost (a layer of gas is formed between a hot surface and the liquid nitrogen, reducing hear transfer efficiency)

How can the disadvantage of using liquid nitrogen in cryo technology be solved?

By using a mixture of solid and liquid nitrogen (can reach -210 degrees Celsius)

Applications for liquid nitrogen in medicine

cryo surgery (local destruction)

conservation (blood, ova, sperm)

Applications for liquid nitrogen in materials engineering

shrink fitting (crimp connection, gear shaft, transmission shaft)

phase transition (removal of retained austenite in hardened steel, shape memory alloys, artificial aging)

Applications for liquid nitrogen in the laboratory

dry nitrogen

gas trap, cryo trap (vacuum pumps, condensation of other gases)

cryo pump (<80K)

What are the two stable nitrogen isotopes?

¹⁴Ni, ¹⁵Ni

What effect does Linde process rely on?

Joule-Thompson effect

What does Joule-Thompson effect state?

a compressed gas cools upon expanding into a low pressure area

Describe the Linde process

air is compressed and passed through a cooler

the cooled high-pressure gas passes through a counter-current heat exchanger, where it is further chilled by the cold, low-pressure gas returning from later stages of the loop

the heavily chilled gas is forced through a throttle valve into a low-pressure chamber

the sudden pressure drop condenses a fraction of the gas into a liquid

the expanded but cooled gas is circulated back to the compressor though the counter-current heat exchanger

What are the three stable isotopes of oxygen?

¹⁶O, ¹⁷O, ¹⁸O

What is the application of ¹⁷O?

NMR

How can oxygen be produced in industry?

fractional distillation of air

electrolysis

adsorption separation on zeolites

membrane separation

How can oxygen be produced in the lab?

thermal or catalytic decomposition of hydrogen peroxide

reversible reaction with barium oxide

What is oxygen used for in medicine

ventilation, pulse oximetry, blood gas analysis

hyperbaric oxygen therapy for CO poisoning

positron emission tomography

What isotope of oxygen is used in PET and why?

¹⁵O

half-life of 2 minutes

What can oxygen be used for in industry?

combustion processes

steel refining through selective oxidation of C, Si, Mn, P

oxidation of heavy crude oil and coal

What is ozone used for?

chemical water treatment

desinfection

deodorisation

bleeching in paper industry