# Strength of a bond in a molecule

solas99

## Homework Statement

Carbon monoxide molecule, which has a reduced mass of 6.85 amu, absorbs infrared radiation wavelength of 4.6um. if the absorption is due to vibrational transitions, calculate the strength of the bond in molecule

## Homework Equations

u=(m1*m2)/(m1+m2)

## The Attempt at a Solution

1. (12*16)/(12+16)=6.85 amu= 1.13e-26 Kg

here i calculate the reduced mass...but the reduced mass is given in the question! i just don't know what equation to use to calculate bond strength from wavelength and reduced mass..

there is another equation for frequency of vibrations: v=1/2pi $\sqrt{k/u}$

but i don't know what k stands for? and how we calculate it
is there any other equation I am missing?

thank you!

Last edited:

Homework Helper
k is called the force constant of stretching the bond between carbon and oxygen, and it characterises the stiffness of this bond. Search your notes what was called "the strength of the bond". You can calculate k from the given data. Remember that a vibrating molecule absorbs that radiation which frequency corresponds its vibrational frequency.

ehild

solas99
E=h(n+1/2)w

solas99
is k the bond strength?

from equation λ=2pic$\sqrt{u/k}$

do we then solve for K, to give the bond strength?

thanks a mill :)

Homework Helper
Well, k is not the bond strength, but your book might call it so. Anyway, calculate it.

ehild