The solute is the substance that you put into water to dissolve.
First, we will get the average pH of the two given values:
average pH = (6.4+8) / (2) = 7.2
At this average pH, the concentration of the acid from the phenol red is equal to the concentration of the base.
pH = 7.2
[H+] = 10^(-7.2) = 6.3 * 10^-8
Phenol red has the general formula HA, this gives us:
HA <.......> H+ + A-
At pH = 7.2, [H+] = [A-]
<span>Ka = [H+][A-]/ [HA]
</span>Ka = [H+] = <span>6.3 x 10^-8</span>
For better representation, let me rewrite the electronic configuration:
<span>1s</span>²<span>2s</span>²<span>2p</span>⁶<span>3s</span>²<span>3p</span>⁶<span>4s</span>²<span>3d</span>⁴
The exponents represent the number of electrons in the designated subshell. Thus, the total number of electrons are:
# of electrons = 2+2+6+2+6+2+4 = 24
Assuming this is in neutral state, the element with an atomic number of 24 is Chromium. Thus, the answer is Cr.
