25.00 mL of unknown calcium hydroxide solution is titrated with 0.400 M standard nitric acid solution. If 38.04 mL of the standard acid solution is required to reach a phenolphthalein endpoint, what is the molarity of the unknown calcium hydroxide solution

Molarity of unknown solution is 0.304 M.

Explanation:

Neutralization reaction:

So, 2 moles of neutralize 1 mol of

Moles of added =

So, 0.0152 mol of neutralize 0.00760 mol of

Let's assume molarity of is C (M)

Then number of moles of in 25.00 mL of C (M) of

=

Hence,

or, C = 0.304

So, molarity of unknown solution is 0.304 M

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."