Answer:
Answer is option D.
The terms vitrification, oxidation, water smoking, and flashing are all associated with firing bricks in a kiln.
Explanation:
Brick is one of the building materials made from the clay. The manufacturing process of brick include;
1) Winning - It is the process of mining of clay and its transportation to the manufacturing site.
2) Preparation - It includes the crushing and grinding of clay and later mixing them into a uniform raw material.
3) Forming/Molding - It is the process of mixing water with the clay mix and mold it into the desired shape. The plasticity of the clay depends on the amount of water used.
4) Drying - The process of removing the moisture from wet clay by drying it through evaporation.
5) Firing and Cooling - Firing is the process of burning the clay in a kiln and it usually requires 40 - 150 hours. The different stages in firing are;
- Water smoking or dehydration stage - It is a process in which free water retained in the pores of the clay after drying gets evaporated under a high temperature of 400-650°C and the clay loses its plasticity. Some of the carbonate minerals are eliminated.
- Oxidation - This process occurs at a very high temperature of 650-900°C in which the ferrous iron is oxidized to the ferric form and the remaining carbon is eliminated.
- Vitrification- This process occurs at a very high temperature of 900- 1100°C for low melting clay and 1000-1250°C for high melting clay, where the clay is transformed into a soft molten mass as a result of an increase in temperature. It gradually loses the shape and transforms into a glassy structure after cooling.
- Flashing - In this process, the fire in the kiln is regulated in such a way that it causes a reduction in the kiln temperature and the cooling process begins which produces color variations in bricks.
6) Drawing - It is the process involving the unloading of the kiln after cooling and packing of the bricks for further shipment.
The basis for spontaneous reactions and their dependence on temperature is given by the equation for the Gibbs Free energy:
ΔG<span> = Δ</span>H<span> – </span>TΔ<span>S < 0
</span>
For a spontaneous reaction to occur, ΔG must be negative. Following the equation, ΔH must be < 0, and ΔS must be > 0 for a reaction to be spontaneous at all temperatures. However, the given values have a negative value for both enthalpy and entropy. This means that spontaneity can only occur below a certain temperature, which can be calculate by setting ΔG as zero. This gives:
ΔG = ΔH – TΔS = 0
T = ΔH/ΔS = -50/-0.3 = <span>166.67 Kelvin
</span>
Anything below that temperature gives a negative ΔG, making it spontaneous.
Answer:
chemical composition
Explanation:
changes into any state of matter are physical and thus the chemical composition of the matter is unaltered
<h2>
Answer: 6 moles</h2>
<h3>
Explanation:</h3>
3 H₂ + N₂ → 2 NH₃
↓ ↓
4 mol 3 mol
Since the moles of N₂ is the smaller of the two reactants, then N₂ is the limiting factor (the reactant that will decide how much ammonia is produced since it has the smaller amount of moles). ∴ we have to use it in calculating the number of moles of ammonia
The mole ratio of N₂ to NH₃ based on the balanced equation is 1 to 2.
∴ the moles of NH₃ = moles of N₂ × 2
= 3 moles × 2
= 6 moles
Paper made from linen is "less" acidic while wood paper is more acidic which also explains which lasts longer. In general, papers that are less acidic don't last as long as papers that aren't as acidic such as linen. Therefore, linen paper lasts longer than wood paper.
I hope I was able to help you with your question. Let me know if you have further questionings based on this information. :)