Calculate the energy of interaction between a lithium ion and a magnesium ion at a distance of 4.55*10^-10

Answer 1

Hello Carley!

This type of problem is solved using Coulomb's law, which states that the energy between two charged species is directly proportional to the magnitude of the charges, and inversely proportional to the distance between them squared. The equation looks like this:

F = k q Q / r²

Where k = 8.99 x 10^9 Nm²/C²

We can find the charge of the Lithium Ion by looking at the periodic table (found to be +1), and we can find the charge of Magnesium the same way (found to be +2). Multiply each of these by the fundamental charge of a proton/electron ( 1.602x10^-19). Since the charges are both positive, the force is repulsive, meaning they push each other apart. To find the magnitude of the force, solve the equation as follows:

F = ( 8.99 x 10^9 Nm² / C²) ( 1.602x10^-19 C) ( 3.204x10^-19 C) / (4.55*10^-10 m)²

F = 1.79 x 10^-26 N

Hope this helps!

Best,

Jake M.