The formula for calculating the monobasic weak acid, the formula for calculating the pH of the monob

In analytical chemistry, the allowable relative error of [H] or OH calculations is generally within 5%. Using this as a criterion, the conditions used by various formulas can be calculated.

Taking the unary weak acid Hb as an example, let its concentration be cmol*L-1 and the dissociation constant is Ka.

Approximate formula [h+]=(-ka+ (ka2+4ka*c)) 2 The conditions for use are: kac 20kw

The simplest formula [h+] = (ka*c).

The conditions of use are: KAC 20KW C KA 400;

The approximate formula for calculating extremely dilute acid [H+]= ((Ka*C)+kW) is used under the following conditions: KAC 20 KW C KA 400;

The exact formula is [h+]3+ka[h+]2—(ka*c+kw)*[h+]—ka* kw=0

The conditions of use are: KAC 20KW C KA 400;

The condition is that the C acid is relatively large, the H+ concentration is much greater than KW, and the C acid is much greater than Ka, the modified formula [H+] = (Ka*C acid) is used

pH = 1 2 (pka-LGC acid).

It would be too troublesome if you didn't fix the contract, so you should read the analysis textbook.

This is only available in college textbooks, and you don't need to learn it in middle school, or there are materials for participating in high school chemistry competitions. I can only tell you so much, if you need to look up this information, I don't have any of it. Hope it helps.

What formula ? What is the formula for calculating the ionization pH of a single weak acid?

Monobasic weak acid. The formula for calculating pH: pH=(pka1+pka2) 1 2, a single weak acid refers to a molecule of a molecule of weak acid in an ideal state, which can be separated from a molecule of hydrogen ions before the electrolysis, and because it is a weak acid, it cannot be completely ionized, for example: fluorination changes to slow hydrogen.

Judge by PH: Shout Clear.

1. Measure the amount and concentration of the known substance Hb.

If the pH is greater than the pH of the same concentration of a strong acid, it means that Hb is a weak acid.

2. Take a certain volume of HB solution, measure its pH, and then dilute it 100 times, if the degree of pH increase is equal to 2 units, then HB is a strong acid; If the degree of pH increase is less than 2 units, Hb is a weak acid.

3. Take the HB solution, measure its pH, and then heat, if the PH becomes smaller, it means that HB is a weak acid (volatile and easily decomposed acids generally do not use this method).

4. Take the Hb solution, measure its pH, and then add a little Nab solid, if the pH becomes larger, it means that Hb is a weak acid.

Monobasic strong acid. Exact: [H]c 4kw 2 Simplest Formula: [H]C

ph＝－lgc

It is generally believed. When C 10 mol l. Available.

Monobasic weak acid. Exact: [h] ka [ha] kw minimalist: [h] kac

When kac 20kw and.

When C ka 500, i.e., C[H], then C-[H]C is available.

Example: HA dissociation of CMOL L.

When equilibrium is reached, [a-].

H+], the equilibrium concentration of the weak acid Ha CH+]ka=[a-][H+] HA [H+]2 (CH+]) Because H+ is small, CH+]C

obtained: h+]=kac).

C(Ag+)*C(Cl-)=4*10-10C(Ag+)=C(Cl-)=2*10-5mol L Solubility = (

g hydrochloric acid ionization of c(h+) = 10 -10

mol l ammonium chloride.

C(H+) = 10 -4 for ionization of water in China

Mol L ion concentration: C(Cl-)>C(NH4+)>C(H+)>C(OH-).