friend

If the last week was a busy and irritable week, then this week must be a week of anxiety and a crash, because test papers will be issued this week.Huskies have been in a state of self-denial since Monday night. Looking at Huskies who was muttering for the Xth time that he will definitely be doomed this semester, he silently took out the earphones and put them on.

During chemistry class the next day, Xiang walked into the classroom, and as expected, saw the husky lying down on the table again, staring blankly at the blackboard in front of him in a daze.

"It's okay." Xiang walked over and put the tinfoil bag in front of Husky, "If you don't do well in the exam, it's impossible for others to do well in the exam. Besides, even if you don't do well in the exam this time, don't you have to do it next time?" Well."

"Oh, I know." Husky sat up from the table, but her eyes were still fixed on a certain point on the blackboard, as if there was something there. "I was just thinking about the extra question the teacher gave us just now. He said that only by doing this extra question can we get an A, otherwise he would only give the highest A-."

Looking at Husky, she was silent for a while, then she patted Husky on the shoulder, "Okay, as long as you are fine. Our experiment today depends on you."

"Of course I'm fine." Husky looked away from the blackboard, she rubbed her hands with a little excitement, and opened the tinfoil, "Today is your sorting ceremony, I really want to know that you and Ermin will be sorted Which college to go to. Also, today's experiment is acid-base neutralization titration, which is my favorite experiment. And, "

Husky hammered his desk excitedly, "I got 72% in math this time, but the average score in the class is 60%, which means, I must be above average. Based on the fact that there are only 8 people in our class, I personally feel that there is a very high possibility that I will be in the top three."

"Very good, very good." Xiang applauded, "I knew you had this ability. You must have this kind of confidence in front of Ermin."

Husky paused for a while while cutting the chicken, and shrank her back, "I, I will try my best..."

Who could have confidence in front of someone he had a crush on, and who was at the level of a crush on Ermin.

Looking at Husky, he really wanted to beat her up.

This time, Ermin walked into the classroom with the ringing of the classroom bell for the first time. Husky looked at her. Ermin's face was a little dark. Husky didn't know what happened, but she still nodded to Ermin, which was regarded as a fight. call.Ermin pursed her lips. She walked to her seat and took out a notebook and pen from her bag without any unnecessary movements.

Rodwick picked up the wizard hat on the podium after the roll call. "I know that the sorting ceremony is based on hats, but there is no magic between us, so we use our Muggle way to draw lots." Rodwick said while taking more than 20 small paper balls of different colors Throwing it into the wizard hat, and then handing the wizard hat to the first student in the first row, he turned around and walked to the blackboard to write down the names of the four colleges.

"Each person takes one, and don't put it back after taking it. The red line is the lion house, the yellow line is the badger house, the blue is the eagle house, and the green is the snake house. Whichever college you draw, come up and write your name. Under this academy, well, let’s start.”

The classroom suddenly boiled up, even those who had no interest in Henry Richard, were very interested in the grouping by lottery.Husky happily watched them draw lots one by one, and then went to the blackboard to write down the college they were assigned to, as if they had won a lottery.

Soon, the wizard's hat was passed into Ermin's hands. Ermin grabbed one from it and handed it to the Prime Minister.Stretching his neck, Husky watched as Ermin opened the ball of paper in his hand.Ermin glanced at it, stood up, and walked over to the blackboard.Xiang also stood up.Husky looked at the wizard hat, there were a few balls of paper in it, Husky licked his lips a little enviously, she also wanted to be sorted, although it was such an irregular sorting...

Ermin came back quickly, and Husky looked up at the names on the blackboard, looking for them.Ermin was assigned to the Eagle Court, and Xiang went to the Snake Court.Huskies suddenly wanted to laugh. Even with such a random draw, they were able to be assigned correctly. It seems that this Muggle version of the sorting ceremony also has some inexplicable magic power.Husky looked at the wizard hat in his hand again. If it was him, where would he draw it?

"Take one." Ermin turned, and she looked at the husky and said, "Try it."

Husky bit his lower lip, the goddess bewitched herself like this, should she...

"Husky." Rodwick called from the podium, and Husky raised his head, "give me the hat."

Husky shrugged his nose, such a good opportunity was missed... She shook her head slightly, and took her hat to the podium.

"Then, let's add 5 points to the Eagle Academy now." Rodwick said, "Everyone has to work hard."

For acid-base neutralization titration, you have to pay as much as the marked price, and you don’t need to pay taxes.At the beginning of the class, Ermin's hand, like Heather's, was raised high like a pole, taking the lead in grabbing more than ten points for the Eagle Academy.Soon the other students couldn't care less, they couldn't watch Ermin get points alone, no matter what the final reward was, they couldn't lose face.All of a sudden, when Rodwick asked a question, almost everyone raised their hands. Whether they knew the answer or not, they had to grab the right to answer the question first. As for the answer, it was not too late to think about it when they raised their hands.

After one class, the students had a great time playing, and the huskies had a great time watching the excitement.

After a 5-minute break, Rodwick led them upstairs to do the experiment. Husky's eyes were shining, acid-base neutralization and titration!It's finally here!

After entering the laboratory, when Rodwick was still explaining the purpose of the experiment to his classmates, Husky stared at the burette in front of him with bright eyes, rubbed his hands, and felt a little ready to move.

As soon as Rodwick started speaking, before Xiang could pick up a pen to write his name, Ermin just opened his mouth, Husky snatched the burette on the table, (just like Ermin and Xianghui snatched her) picked up the funnel and the bottle containing NaOH For the bottle, first rinse the burette with water and then NaOH three times, then refill the burette with NaOH and put it on the butterfly clip.Then Husky picked up the bottle of HCl of unknown concentration, tilted his head and thought for three seconds, poured about ten milliliters into the Erlenmeyer flask, and briefly rinsed it.Then poured 20 ml of HCl into it, added phenolphthalein, and put it under the burette.

Then Husky rubbed her hands excitedly, she looked to the left and right, looked at her Ermin and her face expressionlessly, and licked her canine teeth, "If you two have no objections, then I will start first .”

He looked at Huskies and waved his hands, as if we were going to grab again.

"Wait," Ermin raised her hand, "Before you go on, can you explain, what was the purpose of your group of movements just now?"

Husky puffed her mouth immediately, and she looked at the burette with a little reluctance, as if the burette would run away during the time she explained to Ermin.

"I was just washing up." Husky explained, and Ermin spread out her notebook and began to write. "Because you don't know what was in this burette before, and whether the previous user has cleaned it, so you must wash it with clean water before using it, and then wash it twice with the standard solution you want to use. Up to three times. This can ensure the accuracy of the experimental results to the greatest extent."

"Then why did you want it just now?" Ermin raised her hand, gesticulating on her chest imitating the way Husky just washed the burette.

"That's to wash the entire burette completely." Husky said, "There is no problem with clean water, there are a lot of them anyway. Of course, if you are stricter, you should use DI water. But when using standard solutions, because you have to wash it two or three times, If you fill up the entire burette, it will consume a lot of standard solution, so generally just add a part, then close the gate, put the burette down flat, and roll and wash like this. Then, open the gate again and rinse the head below. You ..."

"Okay," said Ermin, "I see what you're saying."

Husky nodded, and she looked at Ermin with a hint of expectation, "Then can I start now?"

Ermin looked up, looked at the husky who seemed to be about to grab candy, and nodded.

Husky excitedly waved her hand in the air. She took a small beaker and put it under the burette, then stood on tiptoe to confirm that there was no air in the burette. Then she looked at the scale of the liquid and slowly opened it. gate.When the liquid level dropped to a place where Husky was satisfied, Husky closed the gate and recorded the scale of the liquid level.

"And why?" Ermin asked next to Husky.

"It's mainly to confirm the initial scale." Husky stuck out his tongue, "It's okay not to release a little bit, but this is my personal habit. Also, before starting to make sure that there is no air in the tube, Because air also takes up volume."

After Husky finished speaking, she closed her eyes and recalled her operation. After making sure that no steps were missed, she put the Erlenmeyer flask back under the burette, quickly glanced at the scale of the burette, and opened the gate. .The thumb, index finger and middle finger of Husky's left hand pinched the mouth of the bottle and shook it gently.The liquid in the burette decreased steadily, and the colorless solution in the conical flask did not change at all. After looking at the conical flask for a few seconds, I got a little bored, took out my phone and started flipping through it.

Husky didn't show any impatience, she was still shaking the Erlenmeyer flask slowly.Until the scale of the burette moved down by more than 20 ml, with the addition of a drop of NaOH, the uppermost layer of the solution in the Erlenmeyer flask showed a faint pink color, but it was fleeting.

"It's changed color!" Ermine yelled, and the husky didn't seem to hear it. She turned the gate down a little more, and the solution dripped more slowly.But each drop always turned the solution quickly pink and then disappeared.Xiang put down his cell phone and looked at the Erlenmeyer flask with interest.

"When will it be over?" Ermin asked standing behind Husky.

Husky still didn't answer, she concentrated on looking at the Erlenmeyer flask in her hand, adding drop by drop, and finally, it gradually became half a drop.

As the half drop slid down the mouth of the Erlenmeyer flask, the first part of the solution in the Erlenmeyer flask that touched the ground turned dark pink, and then as the husky shook, it turned into a very light pink color, visible to the naked eye. Almost indistinguishable.Husky looked on the table. She picked up her lab report and took the white paper as the background. She lifted the Erlenmeyer flask and observed it carefully while shaking it.

Ermin looked at the Erlenmeyer flask, and she could barely tell that the solution inside was not colorless and transparent, but it was very difficult to say that it had a color.

After about 30 seconds, the light pink color in the conical flask had not subsided, Husky nodded with satisfaction, she put down the conical flask, glanced at the burette, and took down the reading.

"It's interesting, isn't it." Husky turned her head, she looked at Xiang and Ermin, "The colorless solution turned pink just because of that small drop, and it was still such an inconspicuous pink, a little Small and easy to miss, but it does prove that the titration has been done. But you never know where that decisive drop will be, which is funny, isn’t it.”

The prime minister opened her mouth, but she looked at the excited husky and closed her mouth again.

"It's interesting," Ermin said.

Husky smacked his lips and shook his head a little disappointed. The goddess and himself are indeed people from two worlds, "Sorry, sorry."

Ermin raised an eyebrow and picked up her notebook, "Why does the solution in the bottle turn pink?"

"This is because of the addition of phenolphthalein, which is also called an indicator." As Husky said, she took another Erlenmeyer flask, added 20ml of HCl into it, and put it under the burette. She glanced at the burette and made a secret estimate, then took a step back and let the phase beside her.

"Phenolphthalein is colorless in acid and pink in alkali, which is why, when the solution turns pink and remains unchanged for 30 seconds, it proves that the titration is complete. You need to slow down." Husky said Then, she turned down the phase gate.

"But in fact, the color change range of phenolphthalein is above 8, which means." Husky knocked on his Erlenmeyer flask, "The current pH value in it is above 8."

"But it's not neutralization, right? The pH value of neutralization should be in," Ermin flipped forward to flip through his notes, and Husky stood there, looking at the corresponding solution. "It's 7. So, we paid too much?"

Husky laughed out loud.Unknown, he looked up at Husky and Ermin, and Husky immediately closed the valve of the burette.

"Don't leave your eyes from the experimental apparatus before the experiment is finished, especially when it changes at any time, or you stop it." Husky said, she held the gate and opened it again very carefully, this time , the speed of solution dripping slowed down significantly.

"Ermin, to answer your question, yes, we paid too much. But, that's because until now I don't know of any indicator that changes color at exactly 7."

Several Ermins couldn't understand the words that came out of Husky's mouth afterwards. "Litmus is at 5.8, Methyl Orange is 3.1, Methyl Red is 4.4, and..."

"Husky," Xiang called out immediately, preventing the husky from continuing, "now it's starting to change color."

"Well, it's okay." Husky nodded, "I've been watching it all the time, don't worry now, I'll release it drop by drop, don't forget to shake it."

While Husky was talking, she put her hand on the gate, closed the gate every time she put a drop, and carefully put another drop after confirming that the solution in the Erlenmeyer flask had turned colorless again.

The titration of the quick phase was also finished, and the reading was recorded. Husky blinked her eyes. She was a little tired. She didn't have a nap and she was very focused just now, which made her a little dazed and dizzy now.

"I'll do it myself." Ermin noticed Husky's discomfort, she put down the pen in her hand, "Just watch from the side."

Husky frowned, she raised her glasses on the bridge of her nose, rubbed her face, trying to wake herself up. "Feel sorry."

"It doesn't matter." Ermin walked to the front of the burette, and she glanced at the scale on it, "It seems that there is not enough in it, should I add it now or wait until it is used up."

"Now," Husky leaned on the console, rubbed his eyebrows, and shook his head again, "if you add more to the process, it will cause..."

"The result is not accurate," Ermin said.Husky glanced at Ermin and laughed.