Can Heshuang make a solution with warm water?

How do you chat with a female colleague you just met? How do you find a topic?

It's not a very serious thing to not be very talkative, and there are many such people in 2113 in life. So you don't have to mind too much, when you interact with others, don't always think that you have such a problem, always restrain your behavior when talking, always care about your own topic and other people's eyes, so in the eyes of others, you will behave 5261 unnatural.

When chatting with strangers, you should first relax, and then you can talk about things around you, for example, you can ask if you have been busy with work recently, communicate your usual pastime, and recommend some good ** and books. When talking about hot events or interesting things, women can praise the clothes or 4102 people are young, and men can talk about their mental outlook. Lots and lots of them, and they can talk about whatever they like.

Anyway, chatting is the interaction of two or more people, and the topic is not enthusiastic, so you can change the topic. At the same time, when talking for 1653 days, body language can also act as your second language.

Solution preparation: The process of preparing a solution.

There are two types of standard solution configuration: direct configuration method and calibration method.

1) Direct preparation method.

After accurately weighing a certain amount of dried reference material on an analytical balance, dissolving it in water, transferring it to a calibrated volumetric flask, diluting it to the scale with water, and shaking it well, its exact concentration can be calculated.

2) Calibration method.

Many substances do not meet the biological conditions of the reference material, and the standard solution cannot be directly prepared. In general, these substances are prepared into solutions of approximate required concentrations, and then their exact concentrations are determined with reference materials. There are two methods of calibration: direct calibration and indirect calibration, and the systematic error of indirect calibration is larger than that of direct calibration.

There are two standards for the preparation and calibration of standard solutions, namely SH T0079 "Preparation Method of Reagent Solution for Petroleum Product Testing" and GB T601-2002 "Preparation of Standard Titration Solution for Chemical Reagents".

Shelf life of standard solutions.

The standard solution is valid for 3 months, and the following standard solution should be used and prepared.

The commonly used indicator solution is valid for 1 year, and the starch aqueous solution is valid for 1 week.

The name and expiration date of the test solution shall be implemented in accordance with the provisions in the test solution and buffer in the appendix of the current version of the Chinese Pharmacopoeia. If the pharmacopoeia does not clearly stipulate the expiration date, the validity period of the test solution for general testing is 1 year; The expiration date of buffer solutions above pH = 10 is 2 months, and the validity period of buffer solutions below pH = 10 is 3 months.

n c*v= m=m*n=(39+16+1)*balance, dissolve in a beaker, and dissolve with distilled water.

Drain with a glass rod and pour the solution into a volumetric flask (1 L).

Rinse the beaker several times with distilled water and pour the liquid into a volumetric flask.

When the liquid level is about to reach the scale mark, use the rubber tip dropper instead, and the lowest part of the liquid level is tangent to the scale mark.

Cover the bottle and shake well.

Different standard solutions have different standards, and it is recommended to search for the corresponding standard literature first, and then configure according to the standard.

For example, the configuration of potassium hydroxide standard solution in "GB T601-2002, Preparation of Standard Titration Solution for Chemical Reagents" (see figure below).

Pencil ash is graphite, if not specially treated!

The diameter of the particles cannot be between 1 nanometer and 100 nanometers, and they cannot form a solution!

Pencil ash and water.

Pencil ash is carbon and cannot be mixed with water!

Because the graduated cylinder is a measuring instrument, there are often energy changes in the process of dissolving the substance, which may damage the graduated cylinder, such as diluting concentrated sulfuric acid, and the large amount of heat released is easy to burst the graduated cylinder; The diameter of the graduated cylinder is small, which is inconvenient for stirring, so the graduated cylinder cannot be used to prepare solutions.

Use of graduated cylinders:

1) How to inject liquid into a graduated cylinder:

When injecting liquid into the graduated cylinder, hold the graduated cylinder with your left hand to tilt the graduated cylinder slightly, and hold the reagent bottle with your right hand so that the mouth of the graduated cylinder is close to the mouth of the graduated cylinder, so that the liquid flows in slowly. When the amount to be injected is slightly less than the required amount, lay the graduated cylinder flat and use the rubber tip dropper to add the desired amount to the desired amount instead.

2) Scale of the graduated cylinder:

There is no "0" scale for graduated cylinders, and the general starting scale is 1 10 of the total volume.

3) When is the volume of the liquid taken read out?

After injecting the liquid, wait 1 2 minutes for the liquid attached to the inner wall to flow down, and then read the scale value. Otherwise, the value read out is too small.

4) How do I read the volume of the liquid taken?

The graduated cylinder should be placed on a horizontal tabletop, and when observing the scale, the line of sight should be kept level with the lowest part of the concave surface of the liquid in the graduated cylinder, and then the volume of the liquid taken should be read. Otherwise, the reading will be high or low.

5) Can the graduated cylinder heat or measure overheated liquids?

The scale of the graduated cylinder surface refers to the volume at a temperature of 20. As the temperature rises, the cylinder undergoes thermal expansion and the volume increases. It can be seen that the graduated cylinder cannot be heated, nor can it be used to measure overheated liquids, let alone carry out chemical reactions or prepare solutions in the graduated cylinder.

6) Should I rinse the graduated cylinder with water after pouring the liquid from the graduated cylinder?

It depends. If it is only for the measurement to be accurate, there is no need to rinse the cylinder with water, because the cylinder is manufactured with the residual liquid in mind. On the contrary, if the rinse turns the volume taken too large.

If you want to use the same graduated cylinder to measure other liquids, you must rinse them with water to prevent contamination by impurities. Note: The graduated cylinder can generally only be used when the accuracy requirements are not very strict, and is usually used in qualitative analysis, and is generally not used for quantitative analysis, because the error of the graduated cylinder is large.

Graduated cylinders generally do not need to be estimated, because the graduated cylinder is a crude measuring device, but sometimes it is also necessary to estimate, such as the ammeter in the physical electrical meter, whether it is estimated is still inconclusive.

7) On the question of looking up and looking down at the graduated cylinder: when looking at the volume of the graduated cylinder, it is the center point of looking at the water surface, and when looking down, the line of sight is oblique downward, and the intersection of the line of sight and the cylinder wall is on the water surface, so the data read is high, the actual value of the solution is low, and the upward view is the intersection of the line of sight and the cylinder wall under the water surface, so the data read is low, and the actual value of the solution is high.

The graduated cylinder is a measuring device, not a container, not a reaction vessel, not heat-resistant, small in size, and small in caliber, which is not conducive to operation.

The diameter of the graduated cylinder is too small to be suitable, and the bottom is concave when designed, not a horizontal plane, and the solution is uneven.

Potassium permanganate solution needs to use warm boiled water, it is not recommended to use some cold water or the temperature is too high.

Permanganate methyl powder should generally be diluted into a 1:5000 liquid sitz bath, which is generally mixed with warm water and is not easy to react.

If it is potassium permanganate tablets, it can be dissolved with boiling water first, and then mixed with some cold boiled water. Don't overdo it. The ratio to water is 1 in 5000. so as not to burn**.

Potassium permanganate should be mixed with warm or cold water, because potassium permanganate mainly relies on the new ecological oxygen released by organic matter to sterilize. Boiling water to prepare the solution will cause the oxygen ions to be released and decomposed rapidly, thus losing the bactericidal effect.

Warm water is preferred, because potassium permanganate has the property of decomposition when exposed to heat, so when preparing its solution, it is necessary to avoid contact with high temperature environments.

Don't boil water, then potassium permanganate will not work.

Above 40 degrees, it will be invalid pro.

Do not use boiling water when preparing your own solution.

Zhengzhou Kangmuyuan Biotechnology specializes in the production and sales of potassium permanganate.

Warm water, because the high temperature reacts, and then it decomposes in part.

It must be warm water, the water temperature is low and safe, if it is a chemical reaction, when the temperature is high, the reaction is faster, but it is not very safe, it is better to be slow.

Potassium permanganate can be mixed with warm water.

Because the temperature change will occur during preparation, it is easy to cause inaccurate measurement or damage to the graduated cylinder (it is impossible to damage the graduated cylinder, but it should be good to write it like this When you write it, it is inevitable that you will encounter a reaction in the configuration process, or when it is dissolved, there will be a change in heat, resulting in a change in temperature, and the scale of the graduated cylinder will expand and contract, and the reading will be inaccurate.

In general, graduated cylinders and beakers are not used to prepare solutions, because the scale of graduated cylinders and beakers is generally only accurate to 10ml. Preparing solutions requires a high degree of precision. Volumetric flasks and pipettes are generally used for standard solutions, as the accuracy of these two containers is generally achieved.

In other words, if you mix some iodine wine or spices casually in your life, you can use a beaker and a graduated cylinder so-so, but if you configure a chemically pure or analytically pure solution, you must not use a graduated cylinder.

The graduated cylinder is a kind of precision instrument, which cannot be used as a reflection instrument, but in fact, then again, it is absolutely not possible to use a graduated cylinder to configure a solution when answering questions.

But it can't be good with it... Hehe,People are still relatively flexible.。。

Try not to use a graduated cylinder to prepare a solution... In short, the requirements for this kind of more accurate instruments are relatively high.

In addition, volumetric flasks cannot be used as reaction instruments.

Commonly used as reaction instruments are beakers, round-bottom flasks, distillation flasks, incendiary spoons, gas collection cylinders, crucibles, test tubes... There's quite a lot, and I can't remember it at once. Anyway, when answering the question, I refused to say that I couldn't use a graduated cylinder to prepare a solution, but if you really did it in the laboratory, there was actually no big problem.

Follow the textbook.

Because it is inevitable that there will be a reaction in the configuration process, or when it is dissolved, there will be a change in heat, resulting in a change in temperature, and the scale of the graduated cylinder will expand and contract, and the reading will not be accurate.

The composition is constant and corresponds to the chemical formula. If it contains crystal water, the actual content of the crystal water should also be strictly consistent with the chemical formula.

The purity is sufficiently high (above) and the impurity content should be below the tolerance limit of the analytical method.

It is stable in nature, not easy to absorb moisture and carbon dioxide in the air, does not decompose, and is not easy to be oxidized by the air.

There is a large molar mass to reduce the relative error when weighing.

When the reagent participates in the titration reaction, it should be carried out strictly according to the reaction formula, and there is no side reaction.

Introduction: Steps to prepare a solution:

There are two preparation methods, one is the direct method, that is, the reference substance is accurately weighed, and the volume is fixed to a certain volume after dissolution; The other is the calibration method, that is, the concentration is prepared to approximate the required concentration, and then calibrated with a reference substance or a standard solution.

A solution of known accurate concentration, used as a titrant in volumetric analysis, to titrate the substance being measured.

If the reagent meets the requirements of the reference material (the composition is consistent with the chemical formula, the purity is high, and the stability is stable), the standard solution can be prepared directly, that is, the appropriate amount of reference material can be accurately weighed, dissolved and prepared in a certain volume of volumetric flask. The weight of the reference material to be weighed w= v· molar mass of the reference material can be calculated by the following formula: w= v·

where and v are the molar concentration and volume of the solution to be prepared, respectively. The above equation can be used to calculate the concentration of the standard solution.

If the reagent does not meet the requirements of the reference material, a solution is prepared to approximate the desired concentration, and then its concentration is accurately determined with the reference material, a process called solution calibration.

No, SNCL2 will hydrolyze in water.

The degree of du solution is very large, and the equation zhisn2+ +2H2O sn(OH)2+2H+ makes the solution muddy.

DAO turbidity. Standard Matching Replacement Method:

1: Weigh grams of ATTIN chloride.

2: Put the weighed stannous chloride into a 25ml beaker and dissolve it with concentrated hydrochloric acid.

3: Put it in a 105 degree oven and heat it for 10min.

4: After taking it out and cooling it to room temperature, transfer it to a 25ml volumetric flask, and set the volume to 25ml.

5) Add 1 tin pellet and put in the refrigerator.

In this configuration, the hydrolysis of SNCL2 can be inhibited by the addition of hydrochloric acid, and a clear solution can be obtained.

SNCL2 reacts in water as follows.

SnCl2+H2O=sn(OH)Cl+HCl, adding excess hydrochloric acid can inhibit the valve and promote the union.

The bone is responsible for the right to carry out this reaction.

To prepare SNCL2 solution, first calculate the mass of the drug according to the required concentration, weigh the reagent, dissolve it into concentrated hydrochloric acid, and then transfer it to a volumetric flask to determine the volume.

Mainly to prevent hydrolysis. If it is directly dissolved in water, stannous hydroxide precipitation will be produced.

SNCI2 is a commonly used reducing agent, hydrochloric acid is added to prevent hydrolysis of divalent tin ions, and zinc particles are added to prevent divalent tin ions from being oxidized to tetravalent tin ions.