Astudent boils 9.43 grams of an unknown substance into vapor. if completely vaporizing the substance required 8,720 joules of energy, what is the heat of vaporization?

The heat of vaporization is  =924.71  j/g

explanation

Heat of  vaporization is amount  of heat require   to vaporize  1  gram  of a substance.

Heat of  vaporization required is therefore=8720  joules/9.43  grams=924.71   j/g

"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."

the answer for sodium is 0.186

the answer for rubidium is 0.251