At the half equivalence point [HA] = [A-] and pH = pKa
<span>if Ka is 5.2e-5 then pKa = pH = 4.28</span>
Answer:
8.
Explanation:
Atomic number tells us the number of protons in an element. Mass number is the total amount of mass in an atom, and it comes from the sum of the mass of protons and neutrons, which are both considered to have a mass of 1 amu.
If the total mass is 16amu and 8amu comes from the 8 protons, the remaining mass comes from neutrons.
16 - 8 = 8
The molar mass of sodium is 22.99 ㅤ ㅤ ㅤ 22.99 (28) = 643.72 mol now multiply by avogrados number to find the number of atoms. ㅤ ㅤ ㅤ 643.72 (6.022 x 10^23) = 3.88 x 10^26 number of atoms
