Calculate the ph of a buffer that is 0.020 m hf and 0.040 m naf. the ka for hf is 3.5 × 10-4.

The given buffer solution is 0.020 M HF and 0.040 M NaF.

Given the of HF is

Finding out :

=

= 3.46

We use the Hendersen-Hasselbalch equation to find out the pH of a buffer solution:

[Base] =[NaF] = 0.040 M

[Acid] = [HF] =0.020 M

Plugging in the values to find out pH,

pH = 3.46 + log(2)

= 3.76

Therefore, pH of the buffer is 3.76

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.