Question

A water molecule consists of an oxygen atom with two hydrogen atoms bound to it. The angle between the two bonds is 106. If the bonds are 0.10nm long, where is the center of mass of the molecule?

Answer 1

The diagram representing this scenario is shown below

From the information given,

Number of molecules in hydrogen, NH = 1

Number of molecules in oxygen, NO = 15.99

y = 0.1cos53

y = 0.06 nm

x = 0.1Sin53

x = 0.08 nm

r1 = xi + yj = 0.08i + 0.06j

r2 = = 0.08i - 0.06j

r3 = 0

rcm = 2miri/2mi = (m1r1 + m2r2 + m3r3)/(m1 + m2 + m3)

r = 1(0.06i + 0.08j + 0.06i - 0.08j)/2(1 + 1 + 15.99)

r = (6.7 x 10^-3i) nm

the center of mass of the molecule = (6.7 x 10^-3i) nm