A2.6 grams sample of solid naf is dissolved into 250.0 ml of a 0.75 m solution of hf(aq). assuming no significant change of volume, what is the ph of the resulting solution?

pH = 2.7

Explanation:

Please recognize this is a buffer solution question since we have the weak acid HF and its conjugate base F⁻ from the salt NaF.

For buffer solutions we utilize the Henderson-Hasselbach formula to calculate the pH:

pH = pKa + log [A⁻]/[HA]

where pKa  for the acid is given in reference tables, [A⁻] is the molarity of the weak base, and [HA] is the acid concentration.

pKa = 3.2 for HF

[F⁻] = mol Na / Vol (L) = (2.6 g/42 g/mol) / 0.250 L = 0.25 M

[HF] = 0.75 M

plugging our values into the equation:

pH = 3.2 + log (0.25/0.75) = 3.1 - 0.48 = 2.7

Note if you only had Ka for the acid, its pKa is the negative log of Ka.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.