Question

The first if of potassium is `100 mol^(-1)` Calculate the lower potasible frection of light that can ionise a potassium atom

Answer 1

Ionisation energy of potassium` = 100 kcal mol^(-1)`
`= (100 xx 10^(3) xx 4.184)/(6.02 xx 10^(23)) J "atom"^(-1)`
`= 6.95 xx 10^(-19) J "atom" ^(-1)`
`E = hv = 6.95 xx 10^(-19)J "atom"^(-1)`
`:. V = (6.95 xx 10^(-19) J "atom"^(-1))/(h) = (6.95 xx 10^(-19))/(6.62 xx 10^(-34)) = 1.05 xx 10^(15) Hz`