Question

A crystallographer measures the horizontal spacing between molecules in a crystal. The spacing is 10.59 nm . What is the total width of a crystal in millimeters 105 molecules across?

Answer 1

Whenever objects are placed in a line with spaced in between them, the number of spaces is one less than the number of objects. For reference, you may hold up four fingers and count the spaced between your fingers.

Therefore, if there are 105 molecules, then there are 104 spaces present.

We also know that 1 mm = 1000 nm. So, we first convert the spacing to millimeters as the final answer is required in millimeters

spacing = 10.59/1000 = 0.01059 mm

Now, the width of the lattice will be (ignoring the size of the molecules):

104 * 0.01059

1.10 millimeters