How to prepare the buffer solution of pH 4 00 and pH 9 18 buffer solution for PH meter?

Commonly known as standard liquid, now when you buy an instrument, the general manufacturer will come standard with two packs of powdered Dongdong, one package is marked on it; And the other pack is marked, (some come with three packs, yes), which requires you to dilute it, if you are at home, you can dilute it with the purified water you drink, one pack can only be mixed with 250 ml of pure water, shake it until it is fully dissolved, (three packs should be divided into three bottles), if you need to use them many times, put them in a container with a lid, and pour a little bit like a disposable cup to soak the head of the electrode when you use it, and the rest will be covered and set aside. This time you should discard the standard solution so that the remaining standard will not become cloudy.

For general pH measurements, a set of pH buffer reagents (250 m1 can be prepared) can be used, and when preparing the solution, deionized water should be used and boiled in advance for 15 to 30 minutes to remove the dissolved carbon dioxide. Cut open the plastic bag and pour the reagent into the beaker, dissolve it with an appropriate amount of deionized water, rinse the packaging bag, and then pour it into a 250ml volumetric flask, dilute to the scale, and shake well.

Go to the chemical reagent store and buy it, and some sell a large package, divided into three small packets, and there are three kinds of them.

As long as it is dissolved and put in 250ml of deionized water, there is no pH9, it should be.

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 and reduce the influence of external reinforcing acid or strong base on the pH of the solution to a certain extent, so as to keep the pH value of the solution relatively stable.

For example, the ionization of acetic acid and the hydrolysis of sodium acetate are inhibited by the buffer pair of 1 mol l acetic acid and 1 mol l sodium acetate. The concentration of both acetate ions and acetic acid molecules is equal to the amount concentration of the substance in the solution.

ka = c (hydrogen ion) · c (acetate) c (acetic acid). Take the negative logarithm on both sides.

lgka=-lg。

PKA = PH-LG (C(acetate) C(acetic acid)).

pH = PKA+LG (C(acetate) C(acetic acid)).

Generally, for mixed solutions of acids and salts, there is pH = pka+lg[conjugate base conjugate acid.

Generally, for alkali and salt mixed solutions, there is POH = PKB + LG [conjugate acid conjugate base .

For a buffer pair of 1mol l acetic acid and 1mol l sodium acetate.

According to the calculation formula, dilute 10 times with water, the pH is basically the same, and it is still about pH = pka=.

If an equal amount of hydrochloric acid solution is added, pH = pka+.

If an equal amount of sodium hydroxide solution is added, pH = pka+.

If the same amount of hydrochloric acid solution is added to pure water, then pH=, it can be seen that the buffering effect is obvious.

The larger the concentration of the general buffer solution, the ratio of acid-base concentration is close to 1:1, the better the buffering effect, and the buffer is not infinite, and the above two advantages are destroyed if the above two are exceeded, and the buffer range is generally about 1 pH unit up and down.

What is the pH8 9 buffer used for, how is it prepared, please point it out?

Tris-hydroxymethyl aminomethane buffer ( take tris-hydroxymethylaminomethane, add 800ml of water, stir to dissolve, and dilute to 1000ml, and adjust the pH value with 6mol l hydrochloric acid solution to obtain. Tris( take calcium chloride, add 40ml of tris-hydroxymethylaminomethane solution to dissolve, adjust the pH value with 1mol l hydrochloric acid solution, and dilute to 100ml with water. Tris-hydroxymethyl aminomethane buffer ( take tris-hydroxymethyl aminomethane, add lysine hydrochloride, sodium chloride, disodium ethylenediaminetetraacetate, and then add water solubility to make 1000ml, adjust the pH value to, that is.

Barbiturate buffer ruler key answer ( take barbiturate and barbiturate sodium, add water to dissolve into 2000ml, that is. Ammonia ammonium chloride buffer (take ammonium chloride, add water to dissolve it into 100ml, and then add dilute ammonia solution (1 30) to adjust the pH value to obtain. Borax calcium chloride buffer ( take boron Hui sand and calcium chloride, add about 800ml of water to dissolve, adjust the pH value with 1mol l hydrochloric acid solution, and dilute to 1000ml with water.

Boric acid potassium chloride buffer ( take boric acid, add 500ml of potassium chloride solution to dissolve, and then add 210ml of sodium hydroxide solution to obtain. Phosphate buffered saline (take dipotassium phosphate and potassium dibasic phosphate, add water to dissolve into 1000ml, that is.

To prepare a buffer solution with pH = 1, you can choose a strong acid and base buffer system, that is, a strong acid and a strong base are mixed to form a buffer solution. The pH of this buffer system can be controlled by changing the acid-base ratio.

The following is one possible way to prepare a buffer solution with pH = 1:

Prepare hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions.

Pour 10 ml of HCl solution into a 100 ml beaker.

Measure the pH of the solution using a pH meter and fine-tune the pH with NaOH solution if needed until the pH reaches 1.

Dilute the solution to the desired volume, such as 1 L.

Finally, check the pH of the solution using a pH meter to ensure that it is within the desired range (.

Same principle as above.

pH = pka-lg(n acid, n base).

Acid n base) i.e. n acid n base =

Buffer solutions are generally required.

There is a medium buffering capacity, so choose ammonia and NH4CI by n acid n base = i.e. v(nh4+) v(nh3) = assume v total = 1000ml

So v(NH4+) = 640ml V(NH3) = 360ml so concentrated ammonia is needed.

24 ml requires solid NH4CI:

So add solid NH4CI in 972ml of water.

Add 24ml of concentrated ammonia and stir well.

Because pH = pka+lg(cb ca) (cb=nh3 concentration, ca=nh4cl concentration).

So cb ca=10

20 ph buffer buffer solution! Measure 23 what the pH of the buffer solution is.

Based on the information provided in the question, the pH of the buffer solution for 23 strokes can be calculated using the Henderson-Hasselbalch equation. The hunger-initiation equation is: pH = pka + log([a-] ha]) where pka is the acid dissociation constant of the buffer, [a-] is the anion concentration in the buffer solution, and [ha] is the concentration of acid molecules in the buffer solution.

First, the PKA value of the buffer needs to be determined. Since the title does not provide specific information about the buffer, assuming that the buffer is a TRIS buffer, its PKA value is . At the same time, according to the definition of pH, pH is equal to the negative number of pairs of bright limbs with a base of 10 multiplied by the concentration of hydrogen ions.

Knowing the pH and the temperature of the solution, we can convert pH to hydrogen ion concentration using the following formula: [H+] 10 (-pH) Therefore, at 25, the value of [H+] is: [H+] 10 ( = x 10 (-10) mol L According to the Henderson-Hasselbalch equation, we can get:

+ log([a-] ha])log([a-] ha]) = =10 ( = Since the number of acid molecules and anions in the buffer is equal, the sum of the concentrations of [a-] and [ha] is equal to the total concentration, i.e.: [a-] ha] = c where c is the total concentration of the buffer. If we assume c= mol l, we get:

h+] x 10 (-3) mol l substituting this value into the definition of ph gives a pH value at 23 as: ph = log( x 10 (-3)).

Summary. For example, how to prepare 200ml of pH = 1mol L of acetic acid-sodium acetate buffer solution?

Weigh the salt first, and then add acid or alkali dropwise to adjust the pH; You can weigh sodium acetate first, dissolve it in 100ml of water, and then add acetic acid dropwise until the pH is reached.

For example, how to prepare 200ml of pH = 1mol L of acetic acid-sodium acetate buffer solution? Weigh the salt first, and then add acid or alkali dropwise to adjust the pH; You can weigh sodium acetate first, dissolve it in 100ml of water, and then add acetic acid dropwise until the pH is reached.

Swap that 100 for 250

Milliliter. The results are as above, and you see if you want to round them up.

Usually, how your chemistry teacher takes the value, you follow him.

Summary. Hello dear, glad to answer for you. The preparation of the standard buffer solution is:

Bag assembly method and bottle assembly method. The bag assembly method is to prepare the required concentration in a 250ml (or 500ml) measuring flask (choose the size of the measuring flask according to the standard buffer quality in the bag) according to the instructions on the bag. Keep in a polyethylene bottle b).

Bottle assembly method: weigh potassium hydrogen phthalate (KHC8H404 in advance at 115 5, bake for 2 3 h, cool in a dryer), dissolve in water and dilute to 500ml, mix well. Store in a polyethylene bottle.

mol l potassium phosphate monobasic (KH2PO4) and mol l sodium phosphate dibasic (Na2HPO4) mixed with standard buffer solution (25, pHs=.

Preparation of standard buffer solutions.

Hello dear, glad to answer for you. The preparation of standard buffer solutions is: bag assembly method and bottle assembly method.

The bag assembly method is to prepare the required concentration in a 250ml (or 500ml) measuring flask (choose the size of the measuring flask according to the standard buffer quality in the bag) according to the instructions on the bag. Keep in a polyethylene bottle b). Bottle assembly method:

Weigh potassium hydrogen phthalate (KHC8H404 in advance at 115 5, bake for 2 3 h, cool in a dryer), dissolve in water and dilute to 500ml, mix well. Store in a polyethylene bottle. mol l potassium phosphate monobasic (KH2PO4) and mol l sodium phosphate dibasic (Na2HPO4) mixed with standard buffer solution (25, pHs=.

How to prepare CO2-free water?

Pro, the preparation method of carbon dioxide-free water is to boil distilled water or deionized water for at least 10min, or evaporate the water by more than 10%, cover and cool to prepare carbon dioxide-free pure water.

Good. Thank you.

Why phenolphthalein as an indicator?

Pro, to test the acidity and alkalinity of the solution, phenolphthalein indicator is often used because: phenolphthalein is common and easy to obtain (convenient to prepare solution), and has no toxic hazards; Phenolphthalein is a monochromatic indicator that facilitates the observation of discoloration (reddening without color, or fading of redness).

Distilled water for sample impregnation and dilution should not contain CO2, why 1?

Pro, it means that the distilled water used for sample maceration and dilution should not contain CO2, because CO2 dissolved in water will form an acidic form of H2CO3, which will affect the color change of phenolphthalein at the end of titration.