You are asked to prepare a ph = 3.00 buffer solution starting from 1.25 l of a 1.00m solution of hydrofluoric acid (hf) and an excess of sodium fluoride (naf).
what is the ph of the hydrofluoric acid solution prior to adding sodium fluoride?
how many grams of sodium fluoride should be added to prepare the buffer solution? neglect the small volume change that occurs when the sodium fluoride is added.

a. pH=1.59

Hydrofluoric acid is a weak acid, meaning it would not entirely dissociate. The capacity of dissociation of the compound will be given by it's acid dissociation constant ().

We know that the pH is , therefore using the dissociation constant, we can find the concentration of H+.

HF⇄

For this acid

Let's assume x is the unknown amount of the products, and the initial concentration, in this case 1.00M -x is the final amount of the reagent.

Therefore,

Neglecting the x in the numerator, given that the effect over the 1.00 M will be little we obtain that

b. grams NaF=34.65 g

Given the desired pH, and the initial concentration of {HF]=1.25L*1.00M=1.25 mol, we can use

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .