Question

"A certain group one metal combines with Hydrogen, to form a molecule with the formula XH. The equilibrium bond length of this compound is 1.5957 Å. If this molecule exhibits a pure rotational spectrum with a rotational constant of 7.5131cm−1, calculate the molecular weight of metal X."
I thought that you would use a mix of the reduced mass and rotational constant formulas to get:

$1.66e-27(\frac{(m1)(m2)}{m1+m2})=\frac{h/2\pi}{4\pi Bcr^{2} }$

However, that just gives a negative answer, and mass cannot be negative. I am confused and would appreciate any help

Answer 1

Based on the bond length, the molecular weight of the unknown metal X is 23.

What are ionic compounds?

Ionic compounds are compounds which are formed between oppositely charged ions.

When hydrogen combines with the group 1 metals, they form ionic compounds.

The group one metals that combine with hydrogen to firm ionic bonds include:

• Lithium to give Lithium hydride with equilibrium bond length of 0.239Å.
• Sodium to give sodium hydride with equilibrium bond length of 1.896Å.
• Potassium to give potassium hydride with equilibrium bond length of 2.321Å

The molecular weight of lithium is 7 g

The molecularweight of sodium is 23

The molecular weight of Potassium is 39.

Therefore, based on the equilibrium bond length, the molecular weight of the unknown metal X is 23.

Learn more about bond length at: brainly.com/question/3405662