Chapter 134 (1/2)

Shen Yiyun looked at Shi Yang, who was gradually possessed by demons. However, he turned to Li Zheng and asked, ”do you know what the scoring rate of this question was last year?”

Hearing this, Li Zheng pressed his Kirin arm and said, ”well How can one gram be produced by following the steps? ”

”You think too much.” Shen Yiyun glanced at Li Zheng, his head lowered, and his sharp eyes shot out from the angle between the lens and the eyes. ”60% of the students, the final product is 0.”

“？？？” Li Zheng's back spine a cool, ”this can all participate in the final finals of the people, these 40 points are all gone?”

”Yes, by the way, I got only 45 points in the experiment that year, which is also the national gold medal.” Shen Yiyun righted his glasses, learning from his tutor's appearance when installing beeps, and explained coldly.

”Although you have been told the steps of this experimental question, there is still room for blank space. Candidates are required to judge the phenomenon by themselves and adapt to circumstances.”

”A little carelessness can cause side effects.”

”If it is too conservative, the yield will be insufficient.”

”Therefore, doing experiments is not a simple learning method, but a double assessment of theoretical basis and on-the-spot experience.”

”The pure examination expert, will certainly therefore defeat.”

”99 is no exception.”

Li Zheng has always looked at Shi Yang, which is deeply felt.

As for malonaldehyde and salicylic acid, the following two operations are described.

As in the recipe ”a little soy sauce”, ”half a spoon of sugar”, ”stir fry for a moment with a small fire”.

And this is the most important space to play.

Not only need the cook to control the appropriate dosage, but also play on the spot, according to the cooking situation to adjust the technique.

A little carelessness is a rotten dish.

In chemistry, we have to consider the acidity and alkalinity, temperature, reaction, excess reaction, side reaction, catalyst reaction. As long as one mistake is made, the product will be completely different, and the final product will be lost.

In the meantime, the God of cobalt has turned on the switch of the oil bath and started heating and refluxing.

The oil bath pan is a heater similar to an oven, which is used to complete the reactions that need to be heated in the experiment.

However, this reaction will cause evaporation, resulting in experimental loss.

Therefore, it is necessary to place a condenser tube on the beaker to condense the steam into drops and return it to the bottle.

This process usually takes more than half an hour. The experimenter only needs to fix the knob on the oil bath pan at a certain temperature to prepare other things.

But cobalt didn't.

He held the knob in his right hand and lifted his glasses in his left hand, staring at the liquid in the beaker.

Time goes by.

The test solution soon tends to boil.

At this point, the God of cobalt finally turned the knob carefully to control the temperature.

It can be slightly smoothed down, and he adjusts the temperature.

Li Zheng glared.

Is this not Quanjude's roast duck cook?

”He is fighting for time,” Shen Yiyun commented softly

”Why?” Li Zheng asked for advice with an open mind.

”I ask you, what happens when the temperature is too high and the reflux is intense?” Shen Yiyun asked.

”Flooding.” Li Zheng, after all, is a man who has memorized the whole menu, and quickly replied, ”it will produce effusion, which will reduce reaction efficiency and even cause side effects.”

”Very good. Therefore, in this test, when heating and refluxing, it is recommended to use about 80 ° temperature to control the reflux speed in a stable range.” Shen Yiyun said with a smile, ”but Shi Yang is obviously playing with fire, trying to get stuck in the critical point of flooding state and complete the reaction as soon as possible and as effectively as possible.”

Li Zheng nodded and said, ”it's just like people who have to turn on a big fire when cooking noodles, thinking that they can control the pot just now.”

”This metaphor is good...” Shen Yiyun's eyes narrowed and lifted his glasses, ”but they were all silted up.”

”Shh.” Cobalt God raised his hand and made a gesture of closing the voice.

”Er...” Shen Yiyun gritted his teeth and glared.

I understand.

But you're smart, you've just made a big mistake.

Wait for the finished product, see if you can laugh out!

Li Zheng didn't have so much thought, just tried to absorb the learning movement.

In the following time, the cobalt God was as attentive as Li Zheng's brush, and did not say a word.

Precipitation crystallization, filtration, ethanol cleaning, recrystallization Add sodium hydroxide, reheat and reflow Pour the reactant into concentrated hydrochloric acid water