Rotational KE of Cl2 Molecule: Calc Molar Mass 70.0 g/mol

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In summary, the conversation discusses the calculation of the rotational kinetic energy of a diatomic molecule of chlorine (Cl2) with a molar mass of 70.0 g/mol. The formula for rotational kinetic energy is KE=1/2*I*(angular speed)^2, with I representing the moment of inertia. The mass of one molecule of Cl2 is calculated to be 1.16E-22 g, and the formula for moment of inertia is discussed, with the conclusion that it is better to consider the two Cl atoms rotating separately around the center of mass rather than approximating it as a rod.
  • #1
cmilho10
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In a crude model of a rotating diatomic molecule of chlorine (Cl2), the two Cl atoms are 2.00x10^-10 m apart and rotate about their center of mass with angular speed = 1.40x10^12 rad/s. What is the rotational kinetic energy of one molecule of Cl2, which has a molar mass of 70.0 g/mol?

I have tried this problem but I really don't even know where to start..
 
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  • #2
What is the forumla for Rotational Kinetic energy of a an object?
 
  • #3
KE=1/2* I* (angular speed)^2

I=1/12*m*L^2

would mass=140 g?
 
  • #4
Why have you chosen I = 1/12* m*l^2? Are you approximating this as a rod of length L? I don't think that's a good idea becuase most of the mass is concentrated in the atom, not the bond. So I think taking this as two sepearate Cl atoms rotating about the COM is a better idea

Also, the mass will not be 140g. The mass of 1 mol of Cl2 is 70 grams. And you know 1 mol of Cl2 contains around 6.023*10^23 molecules. So what is the mass of 1 molecule?
 
  • #5
ok i got the mass of one to be 1.16E-22

But then what equation for moment of inertia would I use?
 

What is rotational kinetic energy (KE)?

Rotational KE is the energy an object possesses due to its rotation around an axis.

How is the rotational KE of a Cl2 molecule calculated?

The rotational KE of a Cl2 molecule can be calculated using the formula KE = (1/2)Iω^2, where I is the moment of inertia and ω is the angular velocity.

What is the molar mass of a Cl2 molecule?

The molar mass of a Cl2 molecule is 70.0 g/mol.

How is the molar mass of a Cl2 molecule determined?

The molar mass of a Cl2 molecule can be determined by adding the atomic masses of two chlorine atoms, which are 35.5 g/mol each.

What is the significance of calculating the rotational KE and molar mass of a Cl2 molecule?

Calculating the rotational KE and molar mass of a Cl2 molecule can provide valuable information about its physical properties and behavior. It can also be used to study the effects of molecular rotation on chemical reactions and other processes.

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