That incredibly popular palace drama often features iced fruits and ice jars. So, my friend and I, out of curiosity, researched ancient ice-making methods.
Actually, Jiang Shiyue was living in a dormitory at university at the time, and it was extremely hot. Although there was air conditioning, it was only turned on at limited times, making it often unbearable. Influenced by Huanhuan, the sisters in the dormitory suddenly had the idea of making ice in the dormitory.
They bought some potassium nitrate online.
There was a top student in the dormitory at that time, so Jiang Shiyue didn't have to get involved in the ice-making matter. She didn't remember the specific process very clearly.
Jiang Shiyue let go of Yangyang, took a piece of paper, and taught Yangyang while writing.
“First consider the amount of heat required for water to freeze in the summer.
First, assume that our indoor temperature is 30℃, our atmospheric pressure is standard, and the water temperature is around 25℃.
The freezing of water can be divided into two parts: water releases heat from 25℃ to 0℃, and then freezes from 0℃ and releases heat again.
Because Q = cmt. The specific heat capacity of water is 4.2×103 J/(kg·℃)
One liter of water is one kilogram of water. So to cool water at 25°C to 0°C, you need to release 105 kilojoules of heat.
At 0℃, one gram of water releases 80 calories, or 334.8 joules, when it freezes into ice. We only take 334 joules, so one kilogram releases 334K kilojoules.
Therefore, it is estimated that water releases 439 kilojoules of heat when it freezes from normal summer temperature.
Next consider saltpeter.
Saltpeter's main component is potassium nitrate. Industrial-grade saltpeter can reach purity levels exceeding 99.0%. Let's ignore impurities for now. Potassium nitrate has a heat of dissolution of 34.89 kJ/mol.
In Jiang Shiyue's memory, the solubility of potassium nitrate is about 31.6 grams at 20°C. So, assuming that at 25°C, the solubility is 35 grams, the molar mass of potassium nitrate is 101 grams/mol.
So to absorb 439 kilojoules of heat, you need 1270.8 grams of potassium nitrate, which has a density of 2.109 grams per cubic centimeter. That's 602.57 cubic centimeters."
Jiang Shiyue threw down the pen and began to bite his thumb unconsciously.
This result is wrong.
It's not that the calculation was wrong, but it's unrealistic to throw potassium nitrate directly into the water.
Jiang Shiyue scratched her hair in annoyance. She remembered that her roommate in the dormitory had made ice.
Which step went wrong?
At this time, there was a knock on the door.
Continue read on readnovelmtl.com
