Problem 8E

Explain Millikan's oil drop experiment and how it led to the measurement of the electron's charge. Why is the magnitude of the charge of the electron so important?

Solution : The diagram consists of doubly charged cation(red sph eres) and two singly charged anions(blue spheres) thus charge is balanced. The given diagram contains 12 blue spheres and 6 red spheres. Here, the number of cations (red spheres) = 6 the number of anions (blue spheres) =12 The ratio of cations to anions = 6: 12 = 1: 2 (reduced to simplest form). Among the given formulas only Ca(N0 ) satisfies th3 2 e ratio and others i.e, KBr is in the ratio 1:1, K S0 is in the ratio 2:1, Fe (S0 ) i s in the ratio 2:3. 2 4 2 4 3 Hence the formula Ca(N0 ) is con3 2nt with the diagram. Name of the compound is : Calcium nitrate. It is made of 1 atom of Calcium(Ca) and 2 atoms of Nitrate( N0 ) ion. 3