How to prepare buffer 20 and how to prepare buffer

pH standard solution A (

Weigh 110 130 dry for 2 3 h potassium hydrogen phthalate (KH8H4O4) dissolved in water and diluted to 1 L in a volumetric flask

General instrument calibration using buffer school storage room buy (more accurate) has been configured to dissolve the volume that is.

The preparation of the buffer solution is as follows:

1. Select the appropriate buffer pair according to the acidity and alkalinity required, and choose the weak acid and weak salt buffer pair if the acid buffer is prepared; If you are preparing an alkaline buffer, choose a weak base and a weak base salt buffer pair.

2. According to the pH range to be controlled and the dissociation constants (PKb) of weak acids and bases, the specific conjugated acid-base pairs are selected, and the formula is pH PKA1 (14-PKB) 1.

3. According to the formula, calculate the component ratio of the buffer solution, acid buffer pH pka LGC acid C salt, alkaline buffer pH 14-PKB + LGC alkali C salt.

4. Prepare the buffer according to the conjugated acid-base pair and its component ratio, and the method is the same as that of ordinary solution. For example, try to make a buffer with a volume of 1 L and a pH that can be maintained at about the same level.

5. Select the conjugation pair of weak base and weak alkali salt, calculate PKB between PH (14-PKB) 1, check the dissociation constant table of weak base to know that ammonia water (PKB = meets the requirements, so you can choose NH3-NH4Cl system, from pH 14-PKB + LGC alkali C salt, calculate C (ammonia) C (ammonium chloride) 10, let the concentration of ammonia water be 10mol L, then the concentration of ammonium chloride is 1mol L, so the concentration is 10mol L, so the concentration is 10mol l The volume of 1L ammonia water can be added to 1mol of ammonium chloride.

The preparation of the buffer solution is as follows:

Buy acid labels, medium labels, and alkali labels. Wash the three 250ml volumetric flasks with distilled water and let them dry. Note that stoppers should not be mixed. Cut the acid label bag with scissors to extend the edge. Pour the powder into a beaker washed with distilled water.

Add distilled water to the beaker and rinse the acid label bag twice with distilled water to pour the solution into the beaker. Stir slowly with a glass rod to dissolve the solids.

After the solid matter is completely dissolved, let it stand for about 10 min, and the solution is cooled to room temperature. Drain the solution from the beaker into a pre-prepared volumetric flask using a glass rod drainage. Wash the beaker with distilled water and pour into a volumetric flask.

Add distilled water to the volumetric flask until the recess of the liquid level is tangent to the scale mark. Cover the plug and shake it upside down repeatedly.

Precautions. The sample bag containing the sample is rinsed twice and poured into a beaker. The beaker should be rinsed 2 times and poured into a volumetric flask. Wait for the temperature to drop to room temperature before pouring into the volumetric flask. When adding distilled water, be careful not to add tick marks.

Buffer solution is an important concept in inorganic chemistry and analytical chemistry, in analytical testing, in many reactions such as complexation titration and spectrophotometry, the pH value of the solution is required to be kept within a range, to ensure the discoloration of the indicator and the color development of the chromogenic agent, etc., these conditions are achieved by adding a certain amount of buffer solution, so the buffer solution is a reagent often needed in analytical testing.

Precautions for using buffer solutions: Many buffer solutions contain volatile components, such as: ammonia-ammonium chloride in aminocoolic acid-acetic acid in sodium acetate.

Many laboratories have introduced quantitative dosing devices, using quantitative dosing devices to add reagents, with the characteristics of simple and accurate constant error, especially when making batches of samples, it shows its superiority, some people use it to add buffer, but it should be noted that the buffer can not be stored in the quantitative dosing device for a long time, because the vessel is not sealed, it is easy to cause the volatilization of ammonia (acetic acid-acetic acid in sodium acetate buffer is the same), resulting in the failure of the solution, the correct way is that the buffer should be prepared in an appropriate amount, sealed in time after use and stored at low temperature.

The preparation method of commonly used buffer solutions is as follows:

1.Glycine hydrochloric acid buffer (mol L).

x ml mol l glycine + y ml mol l hydrochloric acid, then dilute to 200 ml with water; Glycine molecular weight = , mol l glycine solution contains grams.

2.Phthalic acid hydrochloric acid buffer (

x ml mol l potassium hydrogen phthalate + mol lhcl, diluted to 20 ml with water; Molecular weight of potassium hydrogen phthalate = , mol l potassium hydrogen phthalate solution contains grams.

3.Sodium phosphate dibasic citric acid buffer.

Na2HPO4 molecular weight = , mol l solution is grams;

Na2Hpo4·2H2O molecular weight = , mol l solution contains grams;

C4H2O7·H2O molecular weight = , mol l solution in grams.

4.Citric acid sodium hydroxide-hydrochloric acid buffer.

When using, you can add 1 gram of phenol per liter, if the final pH value changes, adjust with a small amount of 50% sodium hydroxide solution or concentrated hydrochloric acid, and store in the refrigerator.

1. As long as you know the pH value of the buffer pair and the pH value of the buffer to be prepared (and the total concentration of the required buffer), you can calculate the amount of salt and acid according to the formula. The relationship between pH and the amount of buffer pair ions is summarized and listed. As long as you know the pH of the buffer to be prepared, you can calculate the proportion and amount of buffer used by looking up the table.

2. For example, prepare phosphate buffer with a concentration of mol liters.

3. After checking the table, the concentration is molar milliliters, and milliliters of molar Na2HPO4. From this, it can be deduced that milliliters of molar Na2HPO4 are required to prepare molar phosphate buffer, and milliliters of molar Na2HPO4 are required.

4. After the calculation, accurately weigh the solid chemical composition according to the calculation results, put it in a beaker, add a small amount of distilled water to dissolve, transfer it to a 50ml volumetric flask, add distilled water to the scale, shake well, and you can get the required buffer.

5. The preparation of various buffer solutions is mixed according to the proportion, and some reagents must be calibrated to accurate concentration, such as acetic acid, sodium hydroxide, etc. In addition, the preparation and measurement of all buffer solvents can be accurately obtained from the above equations.

Summary. Preparation and properties of buffer solution, according to the dosage, use a pipette to prepare A, B, C and PBS buffer solution for cell culture in four labeled 10ml, 20ml colorimetric tubes, set aside.

How to write this report, brother.

Hello <> Hello Buffer solution is prepared in accordance with the dosage, according to the dosage, use a pipette to prepare A, B, C and PBS buffer macro solution for cell culture in four labeled 10ml, 20ml colorimetric tubes, set aside.

Preparation and properties of buffer solution Purpose of the experiment 1Master the preparation method of Iwaxiangxin buffer solution and deepen the understanding of the nature of its rough wheel. 2.

Master the use of graduated suction tassel tubes and droppers. 3.Learn how a pH meter works to determine the pH of a solution and learn how to use a pH meter.

How do you write this data, am I writing it correctly?

There is also the process of calculation, how to get the calculation formula.

The data is correct.

The preparation principles of the buffer solution mainly include the following points: First, call the head to determine the pH value of the buffer solution. In general, the pH value should be within a certain range and meet the requirements of a specific test, so the pH range should be determined when preparing the buffer solution.

The second is to choose the right buffer. The pH adjustment range of the solution prepared by different buffers can be different from that of celery, and sometimes there is an anticoagulant effect, which may affect the experimental results.

The formula for calculating the pH of the buffer solution is: ph=min*b. Buffer solution refers to a mixed solution composed of weak acid and its salt, weak base and its salt, which can offset the external strengthening acid or strong base to a certain extent.

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Try to format as much as possible.

1. Buffer solution is a reagent that is often needed in analytical testing. In analytical tests, in many reactions such as complexation titration and spectrophotometry, the pH value of the solution is required to be kept within a range to ensure the discoloration of the indicator and the color development of the chromogenic agent, etc., which are achieved by adding a certain amount of buffer solution.

2. The maintenance of the normal physiological environment of our human body is inseparable from the buffer solution, which maintains the normal blood pH range of the human body. Among them, carbonate-sodium bicarbonate is the most important buffer pair in plasma, and the buffering mechanism of this pair is closely related to the respiratory function of the lungs and the excretion and reabsorption functions of the kidneys. The carbon dioxide produced by normal human metabolism enters the blood and combines with water to form carbonic acid, which forms a conjugated acid-base pair with bicarbonate ions in plasma, so the buffer solution is of great significance in medical testing.