Gas is one state of a matter where it has a free particle witch an irregular structure. Whereas solids are a state of a matter where it has structured particles and structures. The changing of state of matter can occur because of the change of temperature inside an object. The changing of state from a gas into solids is called deposition.
The process of this changing of state may occur naturally or even synthetically. Example of deposition that occurs naturally is when a water vapor that turns into a solid snowflake. Whereas the example where deposition occurs synthetically which was not done intentionally is pollution that are caused by the vehicle. Inside a vehicle’s exhaust, we can often find a black soot that dries up into solids because of vehicle engine’s waste. But there are also examples of deposition which are beneficial, like the process of making dry ice from carbon dioxide, the making of ammonium sulfate and ammonium nitrate.
Examples of Gas to Solid (Deposition)
Here are the examples of gas turning into a solid:
- The formation process of snow from water vapor
Water vapor that is gathered in the atmosphere will reach its condensation point where the temperature of the gas turns into solids so that the cloud forms with a less mass than the air. The breaking of the water vapor occurs because the capacity of the cloud is already full. If the breaking is in the form of water particle pouring the earth, it is called the rain which is one of a natural phenomenon that occurs in the troposphere. And if the temperature is below 00C, it will break in the form of snow. Also read: Chemical Properties of Oxidizing Agents
- Black Soot inside a Vehicle Exhaust
Ignition is a chemical reaction between the fuel and the oxygen. In the diesel machine ignition, the solar compound is poured into the ignition system with air adiabatically. The smoke that came out from the diesel is in the form of particulate matter in the exhaust gas containing PAHs and soot.
The black colored gas is a sign of ignition failure. The black soot is to watch out for because it contained carcinogens that can cause cancer to human. The forming of the soot can be reduced by lessening the machine workload. The lesser the workload of the machine, the lesser also the black soot formed. Also read: Examples of Transformation of Gas into Solid Solution
- The Making Process of Dry Ice Using Carbon Dioxide
Charles Thilorier is the first man to observe a solid CO2 in 1835 when he opened a liquid CO2 container that is given a pressure. CO2 will form a solid without going through the liquid phase in the 5.1 atm pressure and about –79°C temperature. These solids are also known as dry ice.
The function of this dry ice is to give a smoke effects from the bottom of a stage. That smoke has a density between 1.2 and 1.6 kg/dm3 Which is bigger than the density of the air so that it won’t go up. You should avoid a direct contact to the dry ice because it can cause frostbites. Other function of dry ice is it is used in a ventilation because it won’t cause respiratory problems. Also read: Examples of Monatomic and Diatomic Gases
- The Making of Ammonium Nitrate Material
Ammonium Nitrate is a nonorganic chemical compound. This compound is used as an explosive materials and raw materials for nitrogen fertilizer. It can be found in the form of powder and prilled.
These are different production process of making Ammonium Nitrate.
- Grainer: This is the oldest process and it is rarely used. This process is done by concentrating the Ammonium Nitrate solution until it reached 98% concentrate at the 305-3100C temperature. The crystallization is done by stirring the solution until it forms a crystal with 0.1% moisture mass inside a Graining Kettle. This process is considered expensive yet dangerous.
- Prilling: Ammoniac gas dan Nitrate acid are reacted with the neutralization reaction inside a reactor that has an exoterm trait by producing vapor. The maximum temperature is 2000C with the concentration product mass that came out having 85% of its mass. The solution is concentrated using a falling evaporator until it has 99,8 % its mass (for explosive industry). Then it is pumped to the prilling tower and the Ammonium nitrate prill that is formed is refrigerated and sieved to get homogenous grains coated with Calcium triphosphate and packed.
- Stengel: Ammoniac gas and Nitratic acid are heated continuously from above the vertical packed reactorwith 2000C maximum temperature. This solution, then, is put inside cyclone separator with the reactor. The output product of the separator is in the form of melted Ammonium Nitrate with contains a water as much as 0.2% of its mass and a temperature of 2000 Then, the melted Ammonium nitrate is dropped a Prilling tower so that it forms a prill or become flakes by cooling it above a drum or belt. That flakes are sieved and coated with Calcium triphosphate inside a drum in order to prevent it from clotting when stored inside a storage or shelf.
- Uhde: This process reacts ammoniac gas and Nitric acid in a bubbling reactor with a neutralization reaction at a 4-5 bar pressure and 2000C temperature. The reactor is put inside a flash drum when the solution came out and concentrated by pumping it to the evaporator. The vapor that came out from the evaporator partially used as a heater and the other is fed to the absorber as the ammoniac gas absorber. After that it enters the prilling tower. The ammoniac nitrate flakes are cooled and screened according to the desired shaped, mostly used, and popularity because of the price. Also read: Gas Laws Definition
- The Making of Ammonium Sulfate ((NH4)2SO4) Material
Ammonium sulfate is a nonorganic salt with a 21% nitrogen contents (ammonium cations) and 24% Sulphur (sulfate anions). It is obtained from the processing of ammonia and sulfuric acid from oven-coke with the chemical reaction as below.
2 NH3 + H2SO4 → (NH4)2SO4
The making process is by mixing ammoniac gas and water vapor into the reactor which contains ammonium sulfate solution around 2-4% of free sulfuric acid solution at 600C temperature. To maintain its acidity, adding a concentrated sulfuric acid is needed. A dry ammonium sulfate powder is formed by spraying sulfuric acid into the reaction container which contains ammoniac gas. The heat produced from the reaction will evaporate all the water in the system which later forms flour-like salts. Also read: Monatomic Gas Definition
Deposition Process Stages
Deposition process in an industrial scale is using the changing of system’s pH method. Other way includes the chemical reaction or evaporation. The main stages in deposition process is:
- Nucleation: Molecules that are dispersed inside a solution or gas phase will form a new bond in the form of nanometer-sized crystal seeds. To stabilize that seeds, the enlarging the size of the crystal seeds is needed.
- Crystal enlargement: To make the crystal seeds bigger and stable, we need to conditioned the seeds by controlling it (adjusting the temperature, degree of saturation, pressure, etc.).
Thereby the explanation regarding examples of gas turning into a solid (deposition.) Hopefully, it is helpful.